CORRESPONDENCE

RESPONSE Re: The Influence of Menstrual Cycle Phase on Surgical Treatment of Primary Breast Cancer: Have We Made Any Progress Over the Past 13 Years?

Gabriel Hortobagyi

Correspondence to: Gabriel Hortobagyi, M.D., F.A.C.P., Department of Breast Medical Oncology, University of Texas M. D. Anderson Cancer Center, 1515 Holcombe Blvd., Box 424, Houston, TX 77030 (e-mail: ghortoba{at}mdanderson.org).

I appreciate Dr. Love’s clarifications to their recent publication in the Journal (1). However, as shown in Fig. 1 of their paper, the authors used the information from 565 of the 709 patients registered in the trial (79%). The other 21% did not fulfill the authors’ own criteria for inclusion in the analysis. I am delighted to learn that the authors planned to look at this aspect of their original study. However, in the original publication of the clinical trial (2), there is no mention of any plan to analyze the outcome of interventions according to the phase of the menstrual cycle. In that same paper (2), the definition of premenopausal was as follows: "having had at least one menstrual period in the preceding 12 months." This hardly suggests that the exact date of the last menstrual cycle was of high priority. Furthermore, in their article in the Journal, the authors’ state that "The results reported here are from exploratory post hoc analyses of subsets of trial participants." This also does not suggest that analyzing the outcome according to phase of menstrual cycle was a major part of the prospective design. Dr. Love and I do agree in that their paper generated a new hypothesis that should be tested in a prospective trial.

Hrushesky glosses over the results presented by Love et al. (1) that show that patients who have their definitive breast surgery at different phases of the menstrual cycle have identical outcomes. This result directly refutes his original hypothesis and the results of previous, retrospective analyses (3,4). Instead, he accepts and endorses the new hypothesis generated by Love et al. (1) that the result of the endocrine intervention varies with the phase of the menstrual cycle during which it is implemented. However, this concept is only indirectly related to Hrushesky’s basic hypothesis. I am pleased that Dr. Hrushesky also espouses the need to prospectively demonstrate the validity of two somewhat related hypotheses that the paper by Love et al. (1) discusses: that breast surgery performed at different phases of the menstrual cycle results in different outcomes and that endocrine therapy of breast cancer implemented in different phases of the menstrual cycle leads to different results. To date, neither has been proven. I agree with his reservations regarding the potential flaws of ongoing prospective trials. However, the last statement of his letter is a reflection of belief rather than evidence. If we have learned anything in medicine over the past century, it is that beliefs, hypotheses, habits, and clinical inertia are not a reliable basis for selecting treatments. We have the appropriate tools to generate rigorous evidence from clinical trials. We should not accept treatments simply because they can be applied or because they are easy to administer. We must base our selections of therapy on demonstrated efficacy and safety.

REFERENCES

1 Love RR, Duc NB, Dinh NV, Shen TZ, Havighurst TC, Allred DC, et al. Mastectomy and oophorectomy by menstrual cycle phase in women with operable breast cancer. J Natl Cancer Inst 2002;94:662–9.[Abstract/Free Full Text]

2 Love RR, Duc NB, Allred DC, Binh NC, Dinh NV, Kha NN, et al. Oophorectomy and tamoxifen adjuvant therapy in premenopausal Vietnamese and Chinese women with operable breast cancer. J Clin Oncol 2002;20:2559–66.[Abstract/Free Full Text]

3 Hrushesky WJ, Gruber SA, Sothern RB, Hoffman RA, Lakatua D, Carlson A, et al. Natural killer cell activity: age, estrous- and circadian-stage dependence and inverse correlation with metastatic potential. J Natl Cancer Inst 1988;80:1232–7.[Abstract]

4 Hrushesky WJ, Bluming AZ, Gruber SA, Sothern RB. Menstrual influence on surgical cure of breast cancer [erratum appears in Lancet 1989 Nov 25;2:1290]. Lancet 1989;2:949–52.[Medline]



             
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