Long-Term Adjuvant Tamoxifen Urged for Low-Risk Breast Cancer

FLORENCE, Italy—Long-term follow-up of node-negative postmenopausal breast cancer patients has shown that using tamoxifen (Nolvadex) as an adjunct to breast-conserving surgery and postoperative radiotherapy markedly improves event-free survival in these low-risk women.

“The positive effect of avoiding salvage mastectomies, re-excisions, and contralateral breast surgery justifies the use of tamoxifen even in the low-risk group with an expected 10-year survival rate of 90%,” Kristina Dalberg, MD, of the Karolinska Hospital, Stockholm, Sweden, said at the First European Breast Cancer Conference. The 432 study subjects comprised a separate stratum of the more than 2,700 women enrolled in the Stockholm Adjuvant Tamoxifen trial. These largely estrogen-receptor (ER)-positive patients were randomized to receive either tamoxifen, 40 mg/day for a mean duration of 3.2 years, or no further treatment, and were monitored for a median follow-up period of 8 years.

Ten-Year Event-Free Survival

Ten-year event-free survival was 80% among women treated with tamoxifen, which was significantly greater than the 70% rate documented among control patients.

This benefit stemmed from a 60% reduction in the relative hazard of invasive or noninvasive ipsilateral breast cancer recurrence and a similar drop in the incidence of contralateral breast tumor development. Dr. Dalberg emphasized that the 3% 10-year rate of ipsilateral recurrence observed among tamoxifen-treated enrollees in the Stockholm study is one of the lowest reported to date.

Although there were trends suggesting a protective effect of tamoxifen against distant metastases and death due to breast cancer, the benefits failed to reach statistical significance.

The study investigators detected six cases of endometrial cancer among tam-oxifen-treated women and two cases in control patients.

The Stockholm results raise the question of whether low-risk women with node-negative, ER-positive breast cancer might be successfully managed with tamoxifen instead of—rather than in addition to—adjuvant radiotherapy.