WESTPORT, Jun 11 (Reuters Health) - Women with ductal carcinoma in situ (DCIS) treated with adjuvant tamoxifen experienced fewer invasive breast cancers during 5 years of treatment, according to an article in the June 12th issue of The Lancet.
Dr. Bernard Fisher, of Allegheny University of the Health Sciences, in Pittsburgh, Pennsylvania, and investigators with the National Surgical Adjuvant Breast and Bowel Project, conducted a randomized, double-blind, placebo-controlled trial involving 1,804 women with DCIS. The researchers compared lumpectomy, radiation therapy, and tamoxifen, 10 mg twice daily, with lumpectomy and radiation therapy alone.
The incidence of breast cancer recurrence decreased by 37% in the tamoxifen-treated women compared with the incidence in women not treated with the drug, according to the results. "There were 43% fewer invasive breast-cancer events and 31% fewer noninvasive breast-cancer events in the tamoxifen group," according to the report.
Though adverse events occurred at similar rates in both groups, there were more endometrial cancers in the tamoxifen group, specifically, "...seven in the tamoxifen group compared with two in the placebo group (relative risk 3.4)," according to the results.
Younger age and positive tumor margins both contributed to an increased rate of recurrent breast cancer, and tamoxifen therapy benefited both these higher risk groups, the authors write.
The report showed no survival advantage with tamoxifen treatment. "At 5 years from study entry," the authors write, "...survival was 97% for the two groups."
"Our findings for ipsilateral-breast tumors are encouraging because they suggest that mastectomy [for DCIS] could be avoided more frequently than at present," Dr. Fisher and associates conclude.
"Moreover," they write, "...the value of tamoxifen used in combination with radiation therapy to lower the occurrence of invasive cancer justifies the suggestion that combined therapy replace mastectomy for the treatment of DCIS patients in whom radiological findings are unlikely to be related to an invasive tumor."
A related commentary written by Dr. Nicholas R. C. Wilcken from Westmead Hospital in Sydney, Australia translates the study's findings into practical terms. "For every 19 women treated with tamoxifen, one [breast-cancer] event was avoided....By extrapolation from the data presented, 22 mastectomies were prevented by tamoxifen, with one mastectomy avoided for every 40 women treated," he says.
"A reasonable view of the data presented should be that the benefits of tamoxifen far outweigh the risks," Dr. Wilcken continues. "Should all women with mammographically detected DCIS have tamoxifen? Probably no. Should most? Probably yes."