Progesterone resistance in women who have had breast cancer

Objective To investigate whether certain physiological responses to luteal progesterone are normal in women previously treated for breast cancer. Design Salivary progesterone concentrations, basal body temperatures, and breast blood flow changes (surface temperature method) were all recorded daily for one natural menstrual cycle. Setting Participants in the study made saliva collections and temperature measurements at home under semi‐standardised conditions with supervisory visits by a project nurse. Participants Twenty‐five controls were compared with 30 women with previous breast cancer; all but three participants were parous and the average ages were 39 years (range 28–48) and 40 years (range 29–46), respectively. On average the women with previous breast cancer had had surgery 2.4 years previously; the operation was usually mastectomy, leaving the contralateral breast for study. Results Follicular phase (day 1–14) oral temperature averages were statistically indistinguishable between women in the control group and those with previous breast cancer. Luteal progesterone profiles were considered in the normal range for the controls and patients. However, the women with previous breast cancer, on average, exhibited a significantly smaller rise in the luteal phase basal body temperature. Follicular phase breast surface temperature was significantly higher in the breast cancer group (+0.30°C). This group showed a highly significant reduction of the luteal heat cycle in their breasts. Conclusions Two progesterone‐mediated physiological mechanisms have been found to be significantly less responsive in women with previous breast cancer than controls. The literature has been reviewed. Progesterone resistance could be a clinical entity and could be important in carcinogenesis.