NEW ORLEANSAdjuvant tam-oxifen (Nolvadex) is as effective among
black women as among white women in reducing the incidence of
contralateral breast cancer, according to a retrospective analysis of
nine trials from the National Surgical Adjuvant Breast and Bowel
Project (NSABP) (B-13 through B-20 and B-22). In addition, increases
in endometrial cancer with tamoxifen use are similar for both races.
Worta McCaskill-Stevens, MD, of the National Cancer Institute,
presented the findings at the 36th Annual Meeting of the American
Society of Clinical Oncology (ASCO).
The results are important because the relative benefit of tamoxifen
among black women has not been thoroughly assessed in clinical trials
and has been considered to be uncertain, said ASCO session moderator,
Frankie Ann Holmes, MD, of US Oncology, Houston.
Dr. Holmes said that discussions at recent conferences indicated that
you could not automatically assume that African-American women
would have the same degree of benefit as Caucasian women because
African-American women have a higher incidence of hypertension,
uncontrolled hypertension, and cardiovascular disease.
The analysis included outcome data from 15,016 patients, of whom
1,212 (8%) were black. That percentage, Dr. McCaskill-Stevens said,
matches the black demographics in the United States. The other
patients were white (n = 12,932) or of other/unknown race (n = 872).
Women with a personal history of breast cancer are at increased risk
for developing a second primary tumor. Depending on age at diagnosis
and other factors, 2% to 11% will develop contralateral disease in
their lifetime, she said.
In the analysis Dr. McCaskill-Stevens and her colleagues compared
rates of contralateral breast cancer, endometrial cancer, and
thromboembolic events (superficial phlebitis, deep vein thrombosis,
or pulmonary embolism).
All of the NSABP trials were double blind and placebo-controlled, and
included 5 years of tamoxifen therapy. Four trials included only
women who were estrogen-receptor (ER) positive and node negative.
Three trials allowed node-positive patients.
Among white women (55% of whom were age 50 are older), 71% and 63%
were ER and progestin-receptor positive, respectively, compared with
55% and 48% of black women (45% of whom were age 50 or older). Nodes
were positive in 43% of white women and 52% of black women.
The annual rate of contralateral breast cancer per 1,000
at-risk patients is strongly dependent on whether the patient is
treated with tamoxifen, Dr. McCaskill-Stevens said.
She said that the annualized rate of 7.4 per 1,000 cases was nearly
uniform across the seven trials with study arms without tamoxifen.
For those study arms with tamoxifen, the rate was 4.4 per 1,000,
representing a 41% reduction in risk.
Dr. McCaskill-Stevens also said that the contralateral breast cancer
rate following primary breast cancer without tamoxifen use was higher
among blacks (9.6% vs 7.2% for whites).
The reduction in risk, however, was nearly identical for both groups.
The contralateral breast cancer rate dropped to 5.5% (RR 0.57, a 43%
reduction) for black women with tamoxifen therapy, and to 4.4% (RR
0.61, a 39% reduction) for white women.
Rates of endometrial cancer increased with tamoxifen in black women
from 0% to 0.8% and in white women from 0.4% to 2.0%. The difference
was not significant. Rates were similar to those recorded in other
trials, she noted.
Thromboembolic events increased three- to fourfold in both groups
with use of tamoxifen (in blacks, from 1.4% to 3.2%, and in whites,
from 1.2% to 4.7%).
Differences in risk and the relative effect of tamoxifen use, after
controlling for protocol, tamoxifen use, chemotherapy, age, and body
mass index, were not significant, Dr. McCaskill-Stevens said.
Differences in effects of receptor and nodal status were also not
significant between the two groups, she added.
In summary, after adjustments for relevant prognostic factors,
African-American women had a higher rate of contralateral breast
cancer, but the difference was not significant. . . . Efficacy
appears to be unrelated to racial differences, Dr. McCaskill-Stevens
Dr. Holmes commented, I am particularly gratified to see this
abstract . . . [and] to know that I can confidently use tamoxifen to
reduce the risk of breast cancer in my African-American