Correspondence to: Richard R. Love, M.D., Department of Medicine, University of Wisconsin Medical School, 1300 University Ave., 7C, Madison, WI 53706 (e-mail: rrlove{at}facstaff.wisc.edu).
Despite admonitions that physicians should discuss current information on tamoxifen with their patients, the preponderance of scientific primary and secondary reports and commentaries focus on relative risk information. While current trial results do not answer several important questions and while our individual risk assessment tools are less than ideal, we can lay out absolute risk and benefit data.
Phillips et al. (1) have helped us all by portraying the impact of breast cancer in a Canadian population. Their life table numbers emphasize that, in a general western population of 1000, the numbers of deaths from breast cancer are small. For example, among women aged 50-54 years and women aged 60-64 years, three deaths might occur in each age group. These numbers emphasize the importance of focusing on women at substantially greater than average risk for this disease.
While there is reluctance to lay out absolute numbers of excess or prevented events associated
with tamoxifen therapy [p. 1383 in (2)], healthy women
considering this issue request such information. Using the actual average annual rates in the P-1
study report (2) and multiplying these rates by 5 (excepting the vasomotor
and gynecologic symptom numbers), the numbers in Table 1 result. It is
notable that some event numbers may in fact represent chance occurrences. The excess levels of
vasomotor and gynecologic symptoms with tamoxifen are consistent with other data; e.g., in a
carefully studied population of postmenopausal women, we found that, after 6 months and 12
months, respectively, an excess of 23% and 27% of tamoxifen recipients reported
substantial overall toxicity (3). Such numbers would suggest dropout
rates higher than those that actually occurred in the P-1 study.
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Until further follow-up data from the P-1 study or from other studies become available, these absolute numbers tell us roughly what we know.
NOTES
Editor's note: Zeneca Pharmaceuticals, the manufacturer of tamoxifen, is supplying the drug at cost for a clinical trial in which Dr. Love is the principal investigator.
REFERENCES
1
Phillips KA, Glendon G, Knight JA. Putting the risk of breast
cancer in perspective. N Engl J Med 1999;340:141-4.
2
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.
3 Love RR, Cameron L, Connell BL, Leventhal H. Symptoms associated with tamoxifen treatment in postmenopausal women. Arch Intern Med 1991;151:1842-7.[Abstract]
4 Early Breast Cancer Trialists' Collaborative Group. Tamoxifen for early breast cancer: an overview of the randomised trials. Lancet 1998;351:1451-67.[Medline]
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