CORRESPONDENCE

Re: Dose and Dose Intensity as Determinants of Outcome in the Adjuvant Treatment of Breast Cancer

William Hryniuk

Correspondence to: William Hryniuk, M.D., Clinical Breast Program, Barbara Ann Karmanos Cancer Institute and Wayne State University, 4100 John R, Detroit, MI 48201.

The results of the CALGB chemotherapy trial 8541 testing total dose and dose intensity were recently analyzed (1). The high arm had twice the total dose and dose intensity of the lower arm. The intermediate arm also had twice the total dose of the lower arm and 33% higher dose intensity. At a median follow-up of 9 years, the difference in disease-free or overall survival between the high and intermediate arms did not reach statistical significance, but both arms were superior to the low arm. The authors concluded that the ". . . higher dose is associated with better disease-free survival and overall survival." However, it is not clear whether they meant a higher total dose, a higher dose intensity, or both.

With the 20-20 vision of hindsight, one can see it would have been useful to have included a fourth arm with a dose intensity half that of the high arm, but a treatment duration twice as long, thus delivering the same total dose. We might then have been able to discern whether total dose or total intensity was the more important parameter.

This trial is a landmark one that guides medical practice and research in adjuvant chemotherapy. It is therefore important to know what the authors really mean when they say ". . . higher dose. . . is associated with better disease-free survival. . . ." Do they think dose-intensity contributed as well as total dose? Or do they think a low dose-intensity double-duration treatment would have produced the same results as the high arm?

REFERENCE

1 Budman DR, Berry DA, Cirrincione CT, Henderson IC, Wood WC, Weiss RB, et al. Dose and dose intensity as determinants of outcome in the adjuvant treatment of breast cancer. J Natl Cancer Inst 1998;90:1205-11.[Abstract/Free Full Text]


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