SAN DIEGOIn a cohort of endometrial cancer patients at M.D. Anderson Cancer
Center, those who had previously developed breast cancer and used tamoxifen did
not have a higher incidence of high-risk histologic subtypes, compared with
breast cancer patients not receiving tamoxifen, reported Brian M. Slomovitz,
MD, at the Society of Gynecologic Oncologists 35th Annual Meeting (SGO abstract
It is well known that tamoxifen reduces the incidence of breast cancer by
50%, but it imposes a two- to sixfold increased risk of developing endometrial
cancer, according to a number of studies. Whether cancers associated with
tamoxifen are more aggressive is unclear, since the study results have been
contradictory on this issue.
"As gynecologic oncologists, we need to know if a history of tamoxifen use
affects the clinical course of endometrial cancer in patients with a history of
breast cancer," Dr. Slomovitz said.
The study was a retrospective chart review of 1,307 patients with
endometrial carcinoma seen at M.D. Anderson between 1990 and 2002. The study
identified 77 patients with breast cancer for whom clinical and pathologic
information was obtained.
Forty of 77 breast cancer patients (52%) had a history of tamoxifen use;
median duration of use was 48 months (range, 6 to 120 months). The median age
at diagnosis of endometrial cancer was 65, and was 59 at the time of breast
cancer diagnosis. A family history of breast cancer was noted for 29% of
patients. There were no significant differences in clinical features between
tamoxifen users and nonusers, and the most common presenting symptom was
abnormal vaginal bleeding.
Endometrioid Type Prevails
More than two thirds of patients stopped taking tamoxifen within 2 months of
their endometrial cancer diagnosis. Patients in whom endometrial cancer
developed while taking tamoxifen were more likely to have endometrioid type
endometrial cancers than women who stopped the drug for other reasons, Dr.
Slomovitz reported, suggesting that tamoxifen appears to play a greater role in
these, rather than high-risk, subtypes.