Characteristics of the menstrual cycle at the time of surgery for breast cancer.

Hormone measurements during the menstrual cycle were assessed in six premenopausal women undergoing breast cancer surgery and ten controls to determine whether the stress of diagnosis and surgery influenced cycle characteristics. There was hormonal evidence for normal ovulation in all cancer and control women, although the length of the luteal phase of the cycle was prolonged because of a delay in menstruation in two cancer patients. The timing of surgery in the cycle did not influence the hormonal data. The hormonal characteristics of the menstrual cycle thus appear to be normally preserved in women during the month in which breast cancer surgery is performed.