Five versus more than five years of tamoxifen for lymph node-negative breast cancer: updated findings from the National Surgical Adjuvant Breast and Bowel Project B-14 randomized trial.
BACKGROUND
Previously reported information from B-14, a National Surgical Adjuvant Breast and Bowel Project (NSABP) randomized, placebo-controlled clinical trial, demonstrated that patients with estrogen receptor (ER)-positive breast cancer and negative axillary lymph nodes experienced a prolonged benefit from 5 years of tamoxifen therapy. When these women were rerandomized to receive either placebo or more prolonged tamoxifen therapy, they obtained no additional advantage from tamoxifen through 4 years of follow-up. Because the optimal duration of tamoxifen administration continues to be controversial and because there have been 3 more years of follow-up and a substantial increase in the number of events since our last report, an update of the B-14 study is appropriate.


METHODS
Patients (n = 1172) who had completed 5 years of tamoxifen therapy and who were disease free were rerandomized to receive placebo (n = 579) or tamoxifen (n = 593). Survival, disease-free survival (DFS), and relapse-free survival (RFS) were estimated by the Kaplan-Meier method; the differences between the treatment groups were assessed by the log-rank test. Relative risks of failure (with 95% confidence intervals) were determined by the Cox proportional hazards model. P values were two-sided.


RESULTS
Through 7 years after reassignment of tamoxifen-treated patients to either placebo or continued tamoxifen therapy, a slight advantage was observed in patients who discontinued tamoxifen relative to those who continued to receive it: DFS = 82% versus 78% (P =.03), RFS = 94% versus 92% (P =.13), and survival = 94% versus 91% (P =.07), respectively. The lack of benefit from additional tamoxifen therapy was independent of age or other characteristics.


CONCLUSIONS
Through 7 years of follow-up after rerandomization, there continues to be no additional benefit from tamoxifen administered beyond 5 years in women with ER-positive breast cancer and negative axillary lymph nodes.
Fisher
B
B
National Surgical Adjuvant Breast and Bowel Project, and Department of Surgery, University of Pittsburgh, PA 15212-5234, USA. bernard.fisher@nsabp.org
Dignam
J
J
Bryant
J
J
Wolmark
N
N
D000328:Adult; D000368:Aged; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000401:mortality; D018572:Disease-Free Survival; D004965:Estrogen Antagonists / Q000627:therapeutic use*; D005260:Female; D006801:Humans; D008207:Lymphatic Metastasis; D008875:Middle Aged; D013629:Tamoxifen / Q000627:therapeutic use*; D013997:Time Factors
D004965:Estrogen Antagonists; D013629:Tamoxifen