METHODS
Data Sources
Data were pooled from six mammography registries that participate in the
Breast Cancer Surveillance Consortium26 (cuturl('http://breastscreening.cancer.gov'))
funded by the National Cancer Institute: (1) San Francisco Mammography
Registry, San Francisco, CA; (2) Group Health Cooperative, Seattle, WA; (3)
Colorado Mammography Advocacy Project, Denver, CO; (4) Vermont
Breast Cancer Surveillance System, Burlington, VT; (5) New Hampshire
Mammography Network, Lebanon, NH; and (6) Carolina Mammography
Registry, Chapel Hill, NC. These registries collect information on screening
and diagnostic mammography examinations performed in their defined
catchment area. Each mammography registry links women in their registry to
a state tumor registry or regional SEER program that collects populationbased
cancer data. Some registries additionally link to pathology databases.
Each registry obtains annual approval from their institutional review board to
collect registry information. Linkage procedures are performed following
human subjects protocols to maintain participant confidentiality.
Subjects
Our study included postmenopausal women aged 50 to 79 years who
underwent bilateral mammography examination indicated by the radiologist
as being performed for screening, between January 1996 and December
2000. Women entered the study at the time of their screening examination
and were observed for 1 year, or until the next screening examination, to
determine if breast cancer was diagnosed. A woman may have had more than
one mammography examination during the study period, and thus, may have
entered the study more than once (n 192,511). Breast cancer was not
uniformly detected during the follow-up period; rather, detection was highest
immediately following a screening examination. Therefore, all analyses were
performed per mammography examination rather than per person-year of
follow-up. Screening examinations that occurred after December 2000 were
excluded to ensure at least 12 months for reporting cancers to tumor
registries after screening examinations.
Women 55 years and older were assumed to be postmenopausal. Women
aged 50 to 54 years were considered to be postmenopausal if both ovaries
had been removed, if they reported that their periods had stopped permanently,
or if they were taking HT. Premenopausal women aged 50 to 54 years
having regular menstrual periods with no HT use were excluded (66,132;
6%). We also excluded women who self-reported breast augmentation
(1%) or prior diagnosis of breast cancer (3%), and women for whom time
between mammography examinations (4%), family history of breast cancer
(8%), or current HT use (17%) was missing.
Measurements and Definitions
For each woman, demographic information and a self-reported breast
health history were obtained at the time of each screening examination by
completing a survey. The survey includes questions about menopausal status,
family history of breast cancer in a first-degree relative, current HT use,women with a uterus who were using HT were considered to be using
estrogen plus progestin, whereas women without a uterus using HT were
considered to be using estrogen only.
Time between mammography examinations was determined using dates of
prior mammography examinations recorded in each mammography registry,
or self-reported information collected at the screening examination. We used
self-reported data, rather than dates of prior mammography examinations
recorded in a registry, to calculate time between mammography examinations
for 6.7% of nonusers, 3.5% of HT users without a uterus, and 9.3% of
HT users with a uterus.
Women were considered to have breast cancer if reports from a breast
pathology database, SEER program, or state tumor registry showed any
invasive carcinoma or ductal carcinoma in situ (DCIS) through December
2001. Women with lobular carcinoma-in-situ only were not considered to
have cancer. All breast cancers were classified according to the American
Joint Committee on Cancer staging system.27 Invasive cancers were categorized
by tumor size, grade, and ER status. The few women (n 55) with
grade 4 tumors (undifferentiated or anaplastic) were included with the group
of women with grade 3 tumors (poorly differentiated).
Statistical Analysis
We stratified the data into three groups based on self-reported current HT
use and history of hysterectomy: (1) no HT use with or without a uterus, (2)
HT use and no uterus (proxy for estrogen only), and (3) HT use and uterus
(proxy for estrogen and progestin use). Frequency distributions of various
risk factors were determined for women in these three groups. Rates and RRs
were calculated using Poisson regression, adjusting for age as a continuous
variable, family history of breast cancer, examination year, time between
mammography examinations, and mammography registry. We standardized
the rates by taking a weighted average of the rates estimated from the Poisson
regression model for each covariate configuration, weighting by the proportion
of women in the study with that covariate configuration. Thus, the same
weights were used for nonusers, estrogen and progestin users, and estrogenonly
users, resulting in an adjustment to the same population. Adjusted
distributions were standardized to the study population using logistic
regression for ER status, and polytomous regression for other tumor
characteristics. We also adjusted all analyses for race. Since the results were
similar, and to minimize the number of women excluded from analyses due
to missing values, we did not adjust for race in the final analyses.
history of hysterectomy, and time between mammography examinations.
Women were considered to have a family history of breast cancer if they
reported having at least one first-degree relative (mother, sister, or daughter)
with breast cancer. Women were considered to be “current HT users” if they
reported using prescription HT at a screening examination. Three registries
collect information on duration of use, which was categorized as less than 5
and 5 years of use. Two registries collect detailed self-report information
on type of HT regimen for women who self-reported “current HT use.” Of
women who reported current HT use and no history of hysterectomy, 80.4%
reported taking estrogen and progestin, 17.8% reported estrogen only, and
1.8% reported progestin only. Of those who reported current HT use and
history of hysterectomy, 87.3% reported taking estrogen only, 12.0%
reported estrogen and progestin, and 0.7% reported progestin only. Thus,作者: tianmei001 时间: 2012-3-18 12:12
Rates of breast cancer (invasive cancer or DCIS diagnosed within 12
months of a screening examination and HT use) and 95% CIs were calculated
per 1000 examinations for the three groups and by decade of age.
Adjusted rates and distributions were calculated for stage (0, I, II, and III
and IV combined), tumor size (invasive cancer 10 mm, 11 to 20 mm,
and 20 mm), tumor grade (1, 2, and 3 and 4 combined), and ER status
(positive and negative).
We calculated RRs comparing those taking estrogen and progestin and
those on estrogen only, with to non-HT users by duration of treatment. We
also calculated RRs comparing the risk of tumor characteristics in estrogen
and progestin users and estrogen-only users, with that of nonusers. We
compared the risk of each more favorable tumor feature (stage 0 or I, size
20 mm, grade 1 or 2, ER-positive) and each less favorable tumor feature
(stage II or higher, size 20 mm, grade 3 or 4, ER-negative). We
dichotomized tumor size at 20 mm and stage at 0 or I since both
parameters are considered early stage disease. To evaluate the impact of
study parameters on our findings, two sensitivity analyses were performed
using the same Poisson regression models described above: 1) for a subset of
women whose time between screens ranged from 9 to 18 months with a
median of 13 months, and 2) including all breast cancers occurring within 24
months of a screening examination.
4315 BREAST CANCER AND POSTMENOPAUSAL HT
We calculated the true-positive and false-negative rates per 1000 examinations
for the three study groups. Adjusted rates were calculated using the
same method as described above. We used simulation to estimate the 95%
confidence intervals, sampling 100,000 values of the regression coefficients
from their joint multivariate normal distribution and calculating the rates for
each sample. We estimated upper and lower limits by the simulated 2.5 and
97.5 percentiles. A screening examination was considered a false-negative
examination if breast cancer was diagnosed within 12 months of a negative
examination (BI-RADS [American College of Radiology, Philadelphia, PA]
assessment of 1, 2, or 3 when associated with short-interval follow-up only
or routine follow-up). A screening examination was considered a truepositive
examination if breast cancer was diagnosed within 12 months of a
positive examination (BI-RADS assessment of 0, 4, 5, or 3 when associated
with a recommendation for immediate follow-up).
RESULTS
A total of 373,265 postmenopausal women underwent
683,435 screening mammography examinations between January
1996 and December 2000, of whom 3,202 developed
breast cancer (2,619 invasive and 583 DCIS) within 12
months of an examination.
HT users were more likely to be younger, white, have had a
previous breast biopsy or surgery, and shorter time period
between mammography examinations and less likely to have a
family history of breast cancer (Table 1).
Among women who developed breast cancer, the mean age at
diagnosis was significantly younger among women using estrogen
and progestin and estrogen only compared with nonusers (61
and 63 years v 66 years; P .001). Overall risk of cancer was
higher among women using estrogen and progestin compared
with nonusers (RR, 1.39; 95% CI, 1.31 to 1.47). There was no
significant increased risk of breast cancer among women using
estrogen alone compared with nonusers (RR, 1.05; 95% CI, 0.99
to 1.12). The rate of cancer increased with age for all three groups
(P .0001) and was higher for each decade of age among women
using estrogen and progestin compared with women using estrogen
only, and compared with nonusers (Table 2).
Rate and Risk of Cancer by Tumor Characteristics and
HT Use作者: tianmei001 时间: 2012-3-18 12:12
The rates of stage 0, I, and II tumor; invasive cancer 20
mm; grade 1, 2, and 3 or 4 disease; and ER-positive disease were
higher among women using estrogen and progestin compared
with women using estrogen only, and compared with nonusers
(Table 3).
Rate and risk of breast cancer was higher among women using
estrogen and progestin for 5 years compared with nonusers
(RR, 1.49; 95% CI, 1.36 to 1.63) (Table 4). Rate and risk of
breast cancer was not increased among women using estrogen
and progestin less than 5 years, or among those using estrogen
Table 1. Study Population Characteristics for 374,465 Postmenopausal Women
Who Underwent 683,435 Screening Mammography Examinations Between
1996 and 2000 by HT Use
Hormone Use (% of patients)*
No HT Estrogen Only Estrogen and Progestin
No. of women 213,660 79,216 81,589
No. of examinations 382,435 151,399 149,601
Age, years
50-59 35 49 55
60-69 34 34 32
70-79 31 17 13
Race or ethnicity†
White 83 90 91
Black 9 6 3
Asian 6 3 4
Native American or Alaskan
Native
1 0 0
Other races 1 1 1
Hispanic 3 2 3
Family history of breast cancer 16 14 12
Previous breast biopsy or surgery† 21 27 23
Time between screens, years
1 6270 70
2 2423 23
3-4 7 4 4
4 8 3 3作者: tianmei001 时间: 2012-3-18 12:13
Abbreviation: HT, hormone therapy.
*Estrogen-only group: HT users without a uterus. Estrogen and progestin group: HT
users with a uterus. Column percentage calculated from number of examinations.
†Missing data: 13% for race, 14% for ethnicity (Hispanic), and 3% for previous
breast biopsy or surgery.
Table 2. Rate of Cancer and 95% CI Among 374,465 Postmenopausal Women Who Underwent Screening Mammography From 1996 to 2000 by HT Use
Hormone Use*
No HT Estrogen Only Estrogen and Progestin
Rate 95% CI Rate 95% CI Rate 95% CI
No. of examinations 382,435 151,399 149,601
No. of cancers 1,803 624 775
Cancers per 1,000 examinations† 4.3 4.2 to 4.5 4.5 4.3 to 4.8 6.0 5.7 to 6.3
Cancers per 1,000 examinations by age, years‡
50-59 3.3 3.1 to 3.6 3.4 3.2 to 3.8 4.5 4.2 to 4.9
60-69 4.6 4.4 to 5.0 4.8 4.4 to 5.2 6.4 5.9 to 6.9
70-79 5.8 5.5 to 6.6 6.0 5.5 to 6.6 7.9 7.2 to 8.6
Abbreviation: HT, hormone therapy.
*Estrogen-only group: HT users without a uterus. Estrogen and progestin group: HT users with a uterus.
†Adjusted for age, family history of breast cancer, examination year, time between mammography examinations, and mammography registry using Poisson regression,
and standardized to the total population.
‡Adjusted for family history of breast cancer, examination year, time between mammography examinations, and mammography registry using Poisson regression, and
standardized to the total population.
4316 KERLIKOWSKE ET AL
only compared with nonusers, irrespective of duration of use
(Table 4).
The risk of tumors associated with more favorable prognostic
characteristics was higher among women using estrogen and
progestin for 5 years compared with nonusers: 41% for DCIS,
51% for stage 0 or I, 59% for invasive cancer 20 mm or smaller,
60% for grade 1 or 2 disease, and 72% for ER-positive disease
(Table 5). The risk of tumors associated with less favorable
prognostic characteristics was also higher among women using
estrogen and progestin for 5 years compared with nonusers:
51% for invasive cancer; 46% for stage II, III, or IV; 24% for
invasive cancer larger than 20 mm; and 54% for grade 3 or 4
disease (Table 5). Except for the increased risk of an ER-positive
tumor (Table 5), overall cancer risk was not higher among
women using estrogen only as compared with nonusers. In a
sensitivity analysis on a subset of women whose time between
screens was approximately 1 year, results were similar to those
presented in Tables 4 and 5 (data not shown), with risk of breast
cancer higher among women using estrogen and progestin for
5 years compared with nonusers (RR, 1.51; 95% CI, 1.32 to
1.72). A separate sensitivity analysis that allowed 24 months for
cancer to occur after a screening examination, found similar
results to those reported in Tables 4 and 5 (data not shown); risk
of breast cancer was higher among women using estrogen and
progestin for 5 years compared with nonusers (RR, 1.55; 95%
CI, 1.40 to 1.71).作者: tianmei001 时间: 2012-3-18 12:13
Table 3. Rate of Breast Cancer per 1,000 Examinations and Distribution of Cancers by Stage, Size, Grade, and Estrogen Receptor
Status Among Postmenopausal Women With Screening Examinations From 1996 to 2000 by HT Use
Hormone Use*
No HT Estrogen Only Estrogen and Progestin
Rate
% of
Cancers Rate
% of
Cancers Rate
% of
Cancers
Stage†
0 0.79 20.8 0.77 19.4 1.11 20.6
I 1.97 51.5 2.21 54.9 2.90 54.3
II 0.91 23.8 0.85 21.6 1.18 21.7
III or IV 0.15 3.9 0.17 4.1 0.19 3.5
Tumor size†‡
10 mm 1.14 36.8 1.19 34.6 1.61 36.9
11-20 mm 1.24 39.7 1.49 43.6 1.90 43.8
20 mm 0.74 23.5 0.71 21.9 0.84 19.4
Tumor grade†‡
1 0.68 24.8 0.78 25.5 1.25 31.9
2 1.20 43.5 1.31 44.2 1.57 41.1
3 or 4 0.87 31.8 0.88 30.2 1.02 27.1
Estrogen receptor
status†‡
Positive 1.96 83.1 2.32 84.2 2.96 89.3
Negative 0.40 16.9 0.38 15.8 0.36 10.7
Abbreviation: HT, hormone therapy.
*Estrogen only group: HT users without a uterus. Estrogen and progestin group: HT users with a uterus.
†Adjusted for age, family history of breast cancer, examination year, time between mammography examinations, and mammography
registry using Poisson regression for rates and logistic/polytomous regression for percentages, standardized to the entire population. Missing
data for non-HT users, HT users without a uterus, and HT users with a uterus: 12%, 13%, and 10% for stage; 12%, 13%, and 13% for tumor
size; 22%, 22%, 20% for tumor grade; and 33%, 28%, and 31% for estrogen receptor status, respectively.
‡Invasive cancer only.
Table 4. Rate of Cancer and 95% CI Among Postmenopausal Women Who Underwent Screening Mammography From 1996 to 2000 by Duration of HT Use
No HT
Duration of Use*
Estrogen Only Estrogen and Progestin
5 Years 5 Years 5 Years 5 Years
No. of examinations 382,435 14,815 67,911 24,819 47,979
No. of cancers 1,803 51 272 81 298
Cancers per 1,000 exams 4.3 3.7 4.0 3.7 6.5
95% CI† 4.2 to 4.5 3.1 to 4.5 3.7 to 4.3 3.2 to 4.3 6.0 to 7.0
Relative risk Referent 0.86 0.92 0.85 1.49
95% CI† 0.71 to 1.03 0.84 to 1.00 0.73 to 0.98 1.36 to 1.63
Abbreviation: HT, hormone therapy.
*Estrogen only group: HT users without a uterus. Estrogen and progestin group: HT users with a uterus.
†Adjusted for age, family history of breast cancer, examination year, time between mammography examinations, and mammography registry using Poisson regression
and standardized to the total population.
4317 BREAST CANCER AND POSTMENOPAUSAL HT
Rate of False-Negative and True-Positive Results per
1,000 Examinations作者: tianmei001 时间: 2012-3-18 12:14
The rate of false-negative examination results increased from
0.77 (95% CI, 0.72 to 0.82) in non-HT users, to 0.83 (95% CI,
0.71 to 0.97) in women using estrogen 5 years, to 1.71 (95%
CI, 1.50 to 1.97) in women using estrogen and progestin 5
years (Fig 1). The rate of false-negative examination results with
stage II or higher disease increased from 0.30 (95% CI, 0.27 to
0.32) in nonusers, to 0.38 (95% CI, 0.33 to 0.46) in women using
estrogen, to 0.74 (95% CI, 0.64 to 0.88) in women using estrogen
and progestin (Fig 1).
The rate of true-positive examination results increased from
3.6 (95% CI, 3.4 to 3.7) in nonusers and 3.3 (95% CI, 3.0 to 3.7)
in women using estrogen 5 years, to 5.0 (95% CI, 4.5 to 5.5)
in women using estrogen and progestin 5 years (Fig 1). The
rate of true-positive examination results with stage II or
higher disease increased from 0.77 (95% CI, 0.72 to 0.82) in
nonusers and 0.75 (95% CI, 0.63 to 0.9) in women using
estrogen, to 1.07 (95% CI, 0.89 to 1.29) in women using
estrogen and progestin (Fig 1).
DISCUSSION
We determined the risk of breast cancer and compared the
tumor characteristics among current HT users with those of
nonusers undergoing screening mammography. The likelihood
of being diagnosed with breast cancer was increased 46% among
current estrogen and progestin users who had used HT for 5
years compared with nonusers, but not among estrogen and
progestin users who had used HT for less than 5 years, or
estrogen only users irrespective of duration of use. This supports
previous evidence demonstrating an increased risk of breast
cancer among postmenopausal women who use estrogen and
progestin hormone therapies for a long duration.3-6,25 The risk of
breast cancer was increased both for tumors with favorable and
unfavorable prognostic characteristics with the excess risk somewhat
greater for early-stage, small, low-grade, ER-positive
tumors than for tumors with a higher stage and grade. Estrogenonly
users were slightly more likely to have ER-positive breast
cancer compared with nonusers, but overall risk of breast cancer
was not increased compared with nonusers.
Current HT use has been reported to increase a woman’s RR
of breast cancer by 2% to 3% per year.2,5-7 Some studies have
reported that estrogen plus progestin regimens may be associated
with a greater risk of breast cancer than estrogen-only regimens,
4-6,28 while other studies report that the increased risk with
estrogen is similar to estrogen plus progestin.2,7 It has been
reported that HT users tend to have more in situ or localized
tumors at detection, possibly because of earlier detection by
mammography.2,29 On the other hand, studies have reported that
the extent of disease among HT users is the same as non-HT
Table 5. Relative Risk of Breast Cancer for a Given Tumor Characteristic (type, stage, size, grade, and estrogen receptor status) Among Postmenopausal Women
Using Hormone Therapy Relative to Nonusers
Tumor Characteristic作者: tianmei001 时间: 2012-3-18 12:15
Estrogen and Progestin Users for 5
Years Versus Nonusers*
Estrogen and Progestin Users for 5
Years Versus Nonusers† Estrogen-Only Users Versus Nonusers‡
RR 95% CI RR 95% CI RR 95% CI
More favorable prognosis
DCIS 1.41 1.24 to 1.60 0.77 0.62 to 0.96 0.98 0.89 to 1.07
Stage 0 or I 1.51 1.37 to 1.66 0.99 0.84 to 1.16 1.07 1.00 to 1.15
Tumor size 20 mm§ 1.59 1.43 to 1.76 0.95 0.80 to 1.13 1.11 1.03 to 1.19
Grade 1 or 2§ 1.60 1.44 to 1.77 0.85 0.71 to 1.02 1.07 0.99 to 1.15
Estrogen receptor-positive§ 1.72 1.55 to 1.90 1.03 0.87 to 1.22 1.14 1.06 to 1.23
Less favorable prognosis
Invasive 1.51 1.38 to 1.66 0.86 0.74 to 1.01 1.05 0.98 to 1.12
Stage II, III, or IV 1.46 1.30 to 1.63 0.65 0.52 to 0.80 0.91 0.84 to 1.00
Tumor size 20 mm§ 1.24 1.09 to 1.42 0.82 0.66 to 1.01 0.91 0.83 to 1.00
Grade 3 or 4§ 1.54 1.37 to 1.73 0.50 0.39 to 0.64 0.98 0.90 to 1.07
Estrogen receptor-negative§ 0.89 0.77 to 1.03 0.71 0.58 to 0.87 0.94 0.86 to 1.04
NOTE. Relative risk (RR) and 95% CI are adjusted for age, family history of breast cancer, examination year, time between mammography examinations, and
mammography registry using Poisson regression, standardized to the total population.
Abbreviation: DCIS, ductal carcinoma in situ.
*n 298 cancers (248 invasive, 50 DCIS) among 47,979 screening examinations; estrogen and progestin group hormone therapy users with a uterus.
†n 81 (68 invasive, 13 DCIS) among 24,819 screening examinations; estrogen and progestin group hormone therapy users with a uterus.
‡n 1,803 (1,483 invasive, 320 DCIS) among 382,435 screening examinations; estrogen only group hormone therapy users without a uterus.
§Invasive cancer only.
Fig 1. White bars indicate a false-negative rate; vertical striped bars indicate
a false-negative rate associated with stage II, III, or IV disease; solid bars indicate
a true-positive rate; and vertical striped bars indicate a true-positive rate associated
with stage II, III, or IV disease. HT, hormone therapy.
4318 KERLIKOWSKE ET AL
users30 or possibly greater, with more stage II or higher disease
cases, and high S phase fraction tumors.19,20 Also, it has been
reported among current or recent users of HT that increased
duration of use may increase the risk of disease spread.2 In the
largest study to date with 3,202 breast cancer cases, we have
shown that after taking into account factors that enhance the
chance of detecting a tumor with good prognostic features, such
as older age31 and routine screening, women using estrogen and
progestin for 5 years are at increased risk of early stage tumors
with a more favorable prognosis. Importantly, we also found that
women using estrogen and progestin are at increased risk of
tumors, with a less favorable prognosis consistent with the
Women’s Health Initiative randomized controlled trial results.25
One explanation of why HT users have tumors with more
favorable prognosis is that current or recent use of HT promotes
growth of pre-existing, clinically latent, hormone-dependent
cancers of low malignant potential, that may not otherwise
become clinically apparent. In support of this hypothesis are the
findings reported by Beral et al2 that risk of breast cancer作者: tianmei001 时间: 2012-3-18 12:15
decreases as time since last HT use increases, such that past users
who have not had HT in more than 5 years are not at increased
risk of breast cancer, regardless of prior duration of use. In
addition, recent oral contraceptive use has been associated with
increased detection of localized tumors that does not persist 10
years or more after cessation of use.32 Other evidence in support
of current or recent HT use acting as a cancer promoter are the
findings that well-differentiated invasive tumors with favorable
histology (papillary, tubular, mucinous, medullary) have been
reported to be more prevalent among HT users than nonusers,33
and that HT users are diagnosed at a younger age compared with
nonusers.15 Our findings that estrogen and progestin users were
younger at diagnosis and more likely to have ER-positive tumors
of smaller size and lower grade compared with nonusers supports
the hypothesis that HT promotes growth of preexisting
clinically latent cancers.
Why would women taking HT undergoing routine screening
mammography be at increased risk of breast cancer with less
favorable prognostic characteristics? Taking HT for more than a
year has been shown to increase mammographic breast density
in approximately 16% to 20% of women,34,35 with greater
increases in mammographic density associated with estrogen and
progestin than with estrogen alone.34,36,37 Increased mammographic
density among women taking HT has been associated
with decreases in the sensitivity and specificity of mammography38-
40 and increases in the minimal detectable size of tumor.41
Consistent with these reports, we found that women using
estrogen and progestin for 5 years have a higher rate of
false-negative examination results, and that these false-negative
examination results are associated with a higher rate of stage II
or higher disease as compared with nonusers. Thus, the
increase in less favorable tumors among long-term estrogen
and progestin users may be due, in part, to tumors obscured by
mammographically dense breasts, that progress between
screening examinations. The higher rate of true-positive
examination results associated with stage II or higher disease
in long-term estrogen and progestin users as compared with
nonusers, suggests that estrogen and progestin also may act
synergistically to promote tumorigenesis and more rapid
tumor growth than estrogen alone.42,43
Most studies have found no significant differences in the ER
profiles of breast cancer in HT users and nonusers.8, 10-15, 18-20,
23,25 One small study reported current HT users are more likely
to be diagnosed with ER positive tumors.9 Another study
reported that only long-term HT use of 57 months or more is
associated with having an ER-positive tumor,4 while one study
reported that estrogen and progestin use is associated with作者: tianmei001 时间: 2012-3-18 12:16
having an ER-positive tumor, but that estrogen therapy is not.24
Given that estrogen causes proliferation of ER-positive breast
cells in vitro and in vivo,44,45 it is not surprising that we found
that women using estrogen and progestin and estrogen only were
more likely to be diagnosed with an ER-positive tumor. We
evaluated a large sample of women recently diagnosed with
breast cancer from 1996 to 2001. During that period, ER status
would have been measured with current, new immunohistochemical
assays that minimize misclassification. Our large sample
size and recent period of evaluation with improved ER
detection methods could account, in part, for our ability to detect
a difference in ER status among HT users and nonusers.
We studied a large number of women with breast cancer with
extensive information on tumor characteristics for these women.
Our ability to control for screening interval (surveillance bias) is
another strength of this study. The accuracy of our data depends
on completeness of cancer reporting to the SEER program, state
tumor registries, and pathology laboratories at the mammography
registries, which has been estimated to be more than 94.3%
complete.46 In addition, the cancer rates reported are within the
range of those reported in the literature, for which follow-up has
been reported to be 99.6%.47,48 Tumor size, stage, grade, and ER
status were missing for between 12% to 33% of tumors, due in
part to a change in coding of tumor size and stage by SEER
programs between July 1998 and 1999, which resulted in some
invasive cancers with an in situ component to be coded with an
unknown size. We are not aware of a tumor-reporting bias to
cancer registries related to HT status or history of hysterectomy.
Our finding of similar proportions of missing tumor characteristic
parameters among the three study groups does not support
a tumor-reporting bias. We inferred that women on HT with a
uterus were taking estrogen and progestin, and that women
without a uterus were taking estrogen only, as consistent with
recommended clinical guidelines49 and detailed information
from a subset of mammography registries in this study. Any
misclassification according to type of regimen would make it
more difficult to find an association between HT use and tumor
characteristics and, thus may have attenuated our findings. In
addition, our finding of enhanced risk of breast cancer among
estrogen and progestin users compared to estrogen only users is
consistent with other reports.4-6 We collected information on HT
use at the time of mammography, lessening the possibility of
recall bias. Information on hormone use was self-reported,
perhaps leading to some misclassification, but this is likely to
have been random and to lead to an underestimation of the
association between HT use and tumor characteristics. We were
4319 BREAST CANCER AND POSTMENOPAUSAL HT
not able to determine if tumor characteristics vary by dose or
specific HT regimens.
Millions of women either consider using or begin HT in the
United States each year. Although most use HT for short-term
symptom management, some women may choose to stay on HT
for longer periods. Postmenopausal women with a uterus who
are considering whether to take or stay on HT should be
informed that: (1) using estrogen and progestin HT for 5
years increases the likelihood of developing breast cancer; (2)
estrogen and progestin and estrogen-only hormone therapies
increase the risk of an ER-positive tumor with a higher risk
associated with combination HT regimens; and (3) cancers
associated with estrogen and progestin hormone therapies
include both tumors with favorable prognostic features and
unfavorable prognostic features.作者: tianmei001 时间: 2012-3-18 12:16
AUTHORS’ DISCLOSURES OF POTENTIAL
CONFLICTS OF INTEREST
The authors indicated no potential conflicts of interest.
REFERENCES
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4321 BREAST CANCER AND POSTMENOPAUSAL HT作者: remenb 时间: 2012-3-18 12:17
1. Wakefield, E. F. , Shelton, M, J. , and Hosking, c. s. (1982)
Clinica Chimica Acta 123, 303.
2. Mullins, T. D. , Dzimian, J. L. , Fike, R. M. and Weiss, S. A.
(1991) Focus 13, 91.
3. Fike, R. M. Pfohl, J. , Jayme, D. , and Weiss, S. A. (1990)
Focus 12, 79.
4. Dhainaut, F. Bihoreau, J, L. Lirochon, J. , Vicentelli, R. , and
Migont, G. (1999) Cytotechnology 10, 33.
5. Csirke, B. , Godwin, G. , and Gorfien, S. (1999) Focus 21, 33. 作者: tianmei001 时间: 2012-3-18 12:27
论 文: 用限定化学成分的培养基培养的CHO细胞生产重组蛋白
STEPHEN F. GORFIEN,JOYCE L. DZIMIAN,MARY LYNN TILKINS,GLENN P. GODWIN AND RICHARD FIKE. Life Technologies, Inc. 3175 Staley Road., Grand Island, NY 14072. U.S.A
1. 摘 要
中国仓鼠卵巢细胞(CHO)的无血清培养,作为一种获得高水平表达重组蛋白,同时简化产物的回收和下游步骤的方法越来越普遍使用。然而,无血清培养基仍然含有一种或多种动物来源的成分,包括白蛋白、胎球蛋白、各种荷尔蒙以及其它蛋白质。我们已经证实从CHO培养基配方中去除动物来源蛋白是可行的。血浆蛋白成分如白蛋白和胎球蛋白可以用植物来源的水解产物代替,尽管这种培养基(CHO III PFM)是无蛋白的,但是其化学成分还是没有限定。CD CHO培养基配方是限定化学成分的,不含动植物来源的蛋白质或水解产物。与其它培养基相比,CD CHO虽然相对其它培养基细胞峰密度和最高表达水平出现时间的滞后,但在该培养基中有更佳的峰密度和最高表达水平。我们通过加入丁酸钠成功提高了在最高细胞密度时的表达水平,重组细胞系在生长和重组产物的表达方面表现出一种反比关系,限制细胞密度的方法可能会有效地增强表达。
2. 前 言
对于大规模培养CHO细胞和重组产物表达,因为与使用血清相关的费用、效果和调控的因素越来越成为问题,所以减少或者去除培养基中的血清成分的方法变得越来越常见。因为无血清培养基可能含有各种未限定成分,包括蛋白质、多肽、蛋白水解物,这些配方是血清培养基的一种改进,但可能并没有去除与血清相关的因素。比无血清培养基进一步改进的是无蛋白培养基。这种无蛋白培养基配方中,传统的成分例如白蛋白、胰岛素和铁传递蛋白被其它的成分替代。然而除非特别标明配方是无蛋白、限定化学成分,培养基中可能包含动植物来源的蛋白水解物,其中可能有促进生长和表达的小分子多肽。我们实验室研制的CHO III PFM培养基是普通的未限定化学成分的无蛋白培养基的一个范例,它含有植物中提取的水解物。我们证明细胞在适应这种培养基之后,与在另外一种无血清培养基CHO-S-SFM II相比,生长相同,而表达水平提高。然而CHO III PFM 去掉植物水解物后,它就不再支持重复传代培养中rCHO细胞的生长。因此一种全新的既无蛋白又是限定化学成分的培养基配方面世了。CD CHO培养基不含动植物来源的或者合成的蛋白质、多肽成分。对于想使用无蛋白培养基和/或限定培养体系的用户,我们调节细胞适应不同的培养基以及调节生长和表达方面的经验是具有指导意义的。
3.材料和方法:
3.1培养基,细胞和培养条件
所有使用的培养基配方都不包含核苷酸而且进行了悬浮培养优化。CHO-S-SFM是一种低蛋白(<100µg/mL)无血清培养基。CHO III PFM是一种基本上没有蛋白质的定制配方,不包含动物来源的蛋白。CD CHO培养基是一种限定化学成分的配方,不包含动植物来源的蛋白质、多肽或者水解产物。
我们现在正在考虑替换工业用培养基中的动物来源的成份。已经证实CHO细胞有可能在完全限定化学成份、不含动植物来源蛋白质、多肽或水解产物的培养基中生长。与无血清培养基(CHO-S-SFM II)和无蛋白、未限定的培养基(CHO III PFM)相比,在CD CHO培养基的批量培养能获得高密度的细胞。在到达细胞密度的峰值后,CD CHO培养基中培养的DHFR扩增的rCHO细胞系出现高表达水平。已经证实丁酸钠是细胞生长的强抑制剂,还能促进蛋白质合成〔6〕。其他人也证实多克隆抗体〔7〕和重组蛋白质〔8、9〕的表达水平在加入丁酸钠之后提高。在我们的研究中,通过加入丁酸钠成功限制了细胞的生长并增强了rCHO细胞的rß-Gal表达水平。然而,浓度和加入时间对蛋白质表达的优化也非常重要。用5L的生物反应器能在CD CHO中大规模培养。我们利用限定化学成份的培养基培养CHO细胞的实验表明您能够有更好的选择,用以替换含血清培养基、无血清或无蛋白但没有限定化学成份的培养基配方。
参考文献
1. Jayme, D. M., Epstein, D. A., Conrad, D. R. (1988)Tetal bovine serum altertives, Nature 334:547-8.
2. Rosa, M. D. (1989) serum substitutes: is there a solution:Biopharm 2:16-17.
3. Lambert, K. J. , and Birch, J. R. (1985) Animal Cell Biotechnology, R. E. Spier and J. B. Griffiths, Eds. (Academic Press,London),pp.85-122.
4. Hll, C. V. , Jacob, P. E. , Ringlod, G. M. , Lee, F. (1983) Expression and regulation of Escherichia coli lacZ gene fusions in mammailian cells. J Mol Appl Gen 2(1):101-109
5. Miller, j. (1972) Experiments in Molecular Genetics. Cold Spring Harbor Laboratory,Cold Spring Harbor NY.
6. Kruh, J. (1982) Eeffects of sodium butyrate, a new pharmacological agent, on cells in culture. Mol Cell Biochem 42:65-82.
7. Oh, S. K. , Vig, P. , Chua, F. , Teo, W. K. , Yap, M. G. S. (1993) Substantial overproduction of antibodies by applying osmotic pressure and sodium butyrate. Biotechnol Bioeng 42:601-610.
8. Dorner, A. J. , Wasley, L. C. , Kaufman, R. J. (1989) Increased synthesis of sereted proteins induces expression of glucose-regulated proteins in butyrate-treated Chinese hamster ovary
cells. J Biol Chem 264(34):20602-20607
9. Palermo, D. P. , DeGraaf, M. E. , Marotti, K. R. , Rehbery, e., Post, L. E. (1991) Production of analytical quantities of recombinant proteins in Chinese hamster ovary cells using sodium butyrate to elevate gene expression. J Biotechnol 19:35-48. 作者: tianmei001 时间: 2012-3-18 12:29
CD CHO培养基 最适宜于悬浮培养的中华仓鼠卵巢细胞的生长,重组蛋白和单克隆抗体的表达。成分中不包含有酚红,可以最小化潜在的雌激素样效应和纯化的问题。成分中不包含有次黄嘌呤和胸(腺嘧啶脱氧核)苷以便于在dhfr-扩增系统中使用。与添加血清、无蛋白和无血清培养基组分相比较,CD CHO培养基证明具有优越的性能。设计是为批次系统设计的,但是它很容易为其它用途修改。
Primary Human Keratinocytes,Cryopreserved in Defined Keratinocyte-SFM——原代人角质细胞被加工和冻存在GIBCO™ 限定角质细胞-SFM培养基中,因而有效的适应了这种培养基。在从冻存中复苏后,5天内细胞可以达到完全的汇合培养。用16群加倍进行寿命性能检测,大多数批号证明具有20+加倍。
High Five™, SFM Adapted——来源于亲本Trichoplusia ni BTI-TN-5B1细胞系的分离克隆,适应于悬浮生长在Express Five™ SFM培养基——最适于High Five™和其它的Trichoplusia细胞系。High Five™细胞系常常通过使用杆状病毒表达系统(BEVS)用来进行重组蛋白的表达。
定货信息 类 型 细胞系 目录号 规 格 价 格 适应无血清培养基 目录号 规 格 价 格
Insect D. Mel 2 10831-014 3 ml 查 询 Drosophila-SFM 10797-017 500 ml 查 询
10797-025 1000 ml 查 询
Insect High Five™ Cells B855-02 3×10 cells/ml 查 询 Express Five® SFM 10486-025 1000 ml 查 询
Insect Sf9 11496-015 3 ml 查 询 Sf-900 II SFM 10902-096 500 ml 查 询
10902-088 1000 ml 查 询
10902-070 10 L 查 询
Insect Sf21 11497-013 3 ml 查 询 Sf-900 II SFM 10902-096 500 ml 查 询
10902-088 1000 ml 查 询
10902-070 10 L 查 询
Mammalian 293-F 11625-019 3 ml 查 询 293 SFM 11686-029 1000 ml 查 询
Mammalian 293-H 11631-017 3 ml 查 询 293 SFM 11686-029 1000 ml 查 询
Mammalian COS-7L 11622-016 3 ml 查 询 VP-SFM 11681-020 1000 ml 查 询
Mammalian CHO-S 11619-012 3 ml 查 询 CD CHO 10743-011 500 ml 查 询
10743-029 1000 ml 查 询
Mammalian Primary Human Keratinocytes 12332-011 1 ml 查 询 Defined Keratinocyte-SFM 10744-019 500 ml 查 询 作者: tianmei001 时间: 2012-3-18 12:33
相关产品 产 品 目录号 规 格 价 格
Blasticidin S HC1 R210-01 50 mg 查 询
Calcium Phospate Transfection Kit K2780-01 75 reactions 查 询
Cellfectin® Reagent 10362-010 1 ml 查 询
Geneticin® (G418 Sulfate), liquid 10131-035 20 ml 查 询
10131-027 100 ml 查 询
Geneticin® (G418 Sulfate), Powder 11811-023 1 g 查 询
11811-031 5 g 查 询
Hygromycin B 10687-010 20 ml 查 询
Lipofectamine™ Reagent 18324-111 0.5 ml 查 询
18324-012 1 ml 查 询
18324-020 4×1 ml 查 询
Lipofectamine™ 2000 11668-027 0.75 ml 查 询
11668-019 1.5 ml 查 询
Plus™ Reagent 11514-015 0.85 ml 查 询
Zeocin™ R250-01 1 g 查 询
R250-05 5 g 查 询
订货信息 Description Formula No. Size Price
rProtease 12563-011 100 ml 查 询
Non-animal, recombinant trypsin substitute used lfor the dissociation of attachment-dependent cell lines. 12563-029 500 ml 查 询
1. Wakefield, E. F. , Shelton, M, J. , and Hosking, c. s. (1982)
Clinica Chimica Acta 123, 303.
2. Mullins, T. D. , Dzimian, J. L. , Fike, R. M. and Weiss, S. A.
(1991) Focus 13, 91.
3. Fike, R. M. Pfohl, J. , Jayme, D. , and Weiss, S. A. (1990)
Focus 12, 79.
4. Dhainaut, F. Bihoreau, J, L. Lirochon, J. , Vicentelli, R. , and
Migont, G. (1999) Cytotechnology 10, 33.
5. Csirke, B. , Godwin, G. , and Gorfien, S. (1999) Focus 21, 33. 作者: tianmei001 时间: 2012-3-18 12:41
论 文: 用限定化学成分的培养基培养的CHO细胞生产重组蛋白
STEPHEN F. GORFIEN,JOYCE L. DZIMIAN,MARY LYNN TILKINS,GLENN P. GODWIN AND RICHARD FIKE. Life Technologies, Inc. 3175 Staley Road., Grand Island, NY 14072. U.S.A
1. 摘 要
中国仓鼠卵巢细胞(CHO)的无血清培养,作为一种获得高水平表达重组蛋白,同时简化产物的回收和下游步骤的方法越来越普遍使用。然而,无血清培养基仍然含有一种或多种动物来源的成分,包括白蛋白、胎球蛋白、各种荷尔蒙以及其它蛋白质。我们已经证实从CHO培养基配方中去除动物来源蛋白是可行的。血浆蛋白成分如白蛋白和胎球蛋白可以用植物来源的水解产物代替,尽管这种培养基(CHO III PFM)是无蛋白的,但是其化学成分还是没有限定。CD CHO培养基配方是限定化学成分的,不含动植物来源的蛋白质或水解产物。与其它培养基相比,CD CHO虽然相对其它培养基细胞峰密度和最高表达水平出现时间的滞后,但在该培养基中有更佳的峰密度和最高表达水平。我们通过加入丁酸钠成功提高了在最高细胞密度时的表达水平,重组细胞系在生长和重组产物的表达方面表现出一种反比关系,限制细胞密度的方法可能会有效地增强表达。
2. 前 言
对于大规模培养CHO细胞和重组产物表达,因为与使用血清相关的费用、效果和调控的因素越来越成为问题,所以减少或者去除培养基中的血清成分的方法变得越来越常见。因为无血清培养基可能含有各种未限定成分,包括蛋白质、多肽、蛋白水解物,这些配方是血清培养基的一种改进,但可能并没有去除与血清相关的因素。比无血清培养基进一步改进的是无蛋白培养基。这种无蛋白培养基配方中,传统的成分例如白蛋白、胰岛素和铁传递蛋白被其它的成分替代。然而除非特别标明配方是无蛋白、限定化学成分,培养基中可能包含动植物来源的蛋白水解物,其中可能有促进生长和表达的小分子多肽。我们实验室研制的CHO III PFM培养基是普通的未限定化学成分的无蛋白培养基的一个范例,它含有植物中提取的水解物。我们证明细胞在适应这种培养基之后,与在另外一种无血清培养基CHO-S-SFM II相比,生长相同,而表达水平提高。然而CHO III PFM 去掉植物水解物后,它就不再支持重复传代培养中rCHO细胞的生长。因此一种全新的既无蛋白又是限定化学成分的培养基配方面世了。CD CHO培养基不含动植物来源的或者合成的蛋白质、多肽成分。对于想使用无蛋白培养基和/或限定培养体系的用户,我们调节细胞适应不同的培养基以及调节生长和表达方面的经验是具有指导意义的。
3.材料和方法:
3.1培养基,细胞和培养条件
所有使用的培养基配方都不包含核苷酸而且进行了悬浮培养优化。CHO-S-SFM是一种低蛋白(<100µg/mL)无血清培养基。CHO III PFM是一种基本上没有蛋白质的定制配方,不包含动物来源的蛋白。CD CHO培养基是一种限定化学成分的配方,不包含动植物来源的蛋白质、多肽或者水解产物。
我们现在正在考虑替换工业用培养基中的动物来源的成份。已经证实CHO细胞有可能在完全限定化学成份、不含动植物来源蛋白质、多肽或水解产物的培养基中生长。与无血清培养基(CHO-S-SFM II)和无蛋白、未限定的培养基(CHO III PFM)相比,在CD CHO培养基的批量培养能获得高密度的细胞。在到达细胞密度的峰值后,CD CHO培养基中培养的DHFR扩增的rCHO细胞系出现高表达水平。已经证实丁酸钠是细胞生长的强抑制剂,还能促进蛋白质合成〔6〕。其他人也证实多克隆抗体〔7〕和重组蛋白质〔8、9〕的表达水平在加入丁酸钠之后提高。在我们的研究中,通过加入丁酸钠成功限制了细胞的生长并增强了rCHO细胞的rß-Gal表达水平。然而,浓度和加入时间对蛋白质表达的优化也非常重要。用5L的生物反应器能在CD CHO中大规模培养。我们利用限定化学成份的培养基培养CHO细胞的实验表明您能够有更好的选择,用以替换含血清培养基、无血清或无蛋白但没有限定化学成份的培养基配方。
参考文献
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9. Palermo, D. P. , DeGraaf, M. E. , Marotti, K. R. , Rehbery, e., Post, L. E. (1991) Production of analytical quantities of recombinant proteins in Chinese hamster ovary cells using sodium butyrate to elevate gene expression. J Biotechnol 19:35-48. 作者: tianmei001 时间: 2012-3-18 12:43
Primary Human Keratinocytes,Cryopreserved in Defined Keratinocyte-SFM——原代人角质细胞被加工和冻存在GIBCO™ 限定角质细胞-SFM培养基中,因而有效的适应了这种培养基。在从冻存中复苏后,5天内细胞可以达到完全的汇合培养。用16群加倍进行寿命性能检测,大多数批号证明具有20+加倍。 作者: tianmei001 时间: 2012-3-18 12:45
High Five™, SFM Adapted——来源于亲本Trichoplusia ni BTI-TN-5B1细胞系的分离克隆,适应于悬浮生长在Express Five™ SFM培养基——最适于High Five™和其它的Trichoplusia细胞系。High Five™细胞系常常通过使用杆状病毒表达系统(BEVS)用来进行重组蛋白的表达。
定货信息 类 型 细胞系 目录号 规 格 价 格 适应无血清培养基 目录号 规 格 价 格
Insect D. Mel 2 10831-014 3 ml 查 询 Drosophila-SFM 10797-017 500 ml 查 询
10797-025 1000 ml 查 询
Insect High Five™ Cells B855-02 3×10 cells/ml 查 询 Express Five® SFM 10486-025 1000 ml 查 询
Insect Sf9 11496-015 3 ml 查 询 Sf-900 II SFM 10902-096 500 ml 查 询
10902-088 1000 ml 查 询
10902-070 10 L 查 询
Insect Sf21 11497-013 3 ml 查 询 Sf-900 II SFM 10902-096 500 ml 查 询
10902-088 1000 ml 查 询
10902-070 10 L 查 询
Mammalian 293-F 11625-019 3 ml 查 询 293 SFM 11686-029 1000 ml 查 询
Mammalian 293-H 11631-017 3 ml 查 询 293 SFM 11686-029 1000 ml 查 询
Mammalian COS-7L 11622-016 3 ml 查 询 VP-SFM 11681-020 1000 ml 查 询
Mammalian CHO-S 11619-012 3 ml 查 询 CD CHO 10743-011 500 ml 查 询
10743-029 1000 ml 查 询
Mammalian Primary Human Keratinocytes 12332-011 1 ml 查 询 Defined Keratinocyte-SFM 10744-019 500 ml 查 询 作者: tianmei001 时间: 2012-3-18 12:46
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