CORRESPONDENCE

Re: Tamoxifen for Prevention of Breast Cancer: Report of the National Surgical Adjuvant Breast and Bowel Project P-1 Study

Steven Narod

Correspondence to: Steven Narod, M.D., FRCPC, Centre for Research on Women's Health, University of Toronto, 790 Bay St., 7th floor, Toronto, ON, Canada M5G 1N8.

Fisher et al. (1) demonstrate a statistically significant reduction in the incidence of invasive and noninvasive cancers of the breast associated with tamoxifen use. There was a nonsignificant decline in breast cancer mortality observed as well (six deaths from breast cancer in the placebo arm versus three in the treatment arm); however, the study was not designed with mortality as the principal end point. Nevertheless, it is interesting to note that there was a statistically significant decline in all cancer deaths (42 versus 23; relative risk [RR] = 0.55; 95% confidence interval [CI] = 0.33-0.91; P = .018). The magnitude of the decline in mortality was similar for cancer of the breast (RR = 0.50; 95% CI = 0.13-1.96; P = .33) as for cancers of other sites (RR = 0.56; 95% CI = 0.33-0.96; P = .033), but it was statistically significant for the latter. There were 97 incident cancers (other than cancer of the breast or endometrium) detected in each group. Although the incidence was identical, the case fatality was much higher in the placebo group. Thirty-five of the women in the placebo group died of their cancer compared with 20 women in the treatment group (P = .017). Either this mortality reduction is a chance finding, or tamoxifen use is associated with the development of cancers of a more benign type or retards the progression of a range of cancer types.

REFERENCES

1 Fisher B, Costantino JP, Wickerham DL, Redmond CK, Kavanah M, Cronin WM, et al. Tamoxifen for prevention of breast cancer: report of the National Surgical Adjuvant Breast and Bowel Project P-1 study. J Natl Cancer Inst 1998;90:1371-88.[Abstract/Free Full Text]


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