An expert panel of seven cancer researchers and a representative of the National Alliance of Breast Cancer Organizations (NABCO) came together at the San Antonio Breast Cancer Symposium for a roundtable discussion of the use of tamoxifen(Drug information on tamoxifen) (Nolvadex), sponsored by PRR, Inc., publisher of Oncology News International and the journal ONCOLOGY.
Last month, an article based on the roundtable focused on the possible risks of secondary cancers with tamoxifen use. This report covers the appropriate duration of tamoxifen therapy. Future articles in this series will include the panel's discussion of possible noncancer benefits of tamoxifen and how to deal with side effects.
SAN ANTONIO--The National Cancer Institute, in a clinical announcement, has recommended that physicians limit tamoxifen (Nolvadex) use in the treatment of early breast cancer to 5 years in clinical practice.
"But nobody really has done a valid comparison to determine an optimal duration," said V. Craig Jordan, PhD, DSc, of Northwestern University, who chaired the tamoxifen roundtable. He believes that the question of 5 vs 10 years is "almost a null hypothesis. You won't be able to detect any difference with clinical trials as they are set up because they are not large enough."
The NCI announcement came on the heels of the decision by the National Surgical Adjuvant Breast and Bowel Project (NSABP) to stop a clinical trial (B-14) comparing 5 and 10 years of tamoxifen use after surgery in women with node-negative, estrogen-receptor (ER)-positive breast cancer.
In this trial, 1,172 women who had been on tamoxifen for 5 years and had not relapsed were randomized a second time to either 5 more years of tamoxifen, 20 mg/day, or placebo. After 4 years of follow-up, 92% of the placebo group were alive and free of disease, compared with 86% of the group scheduled to receive 10 years of tamoxifen.
C. Kent Osborne, MD, of the University of Texas Health Science Center, San Antonio, said that ideas on tamoxifen duration have changed over the last 10 years. Initially, he said, it was felt that since tamoxifen seemed to be predominantly a cytostatic agent, it might be best to continue the drug for a longer period of time, maybe indefinitely.