[Study of breast cancers during pregnancy and lactation]

From breast cancer cases that were mastectomized between 1970 and 1987 at the Cancer Institute Hospital, 43 breast cancers during phases of pregnancy and lactation (pregnancy 11 cases, lactation 32 cases) have been analyzed. Taking the patient's age and the calendar-year at the time of diagnosis into account, we collected 43 cases as controls and compared the result. It was found that breast cancers during pregnancy and lactation metastasized to the lymph nodes at the same frequency as in the control cases, in lymph node-positive cases and in tumors of the same size the metastases involved more lymph nodes than in the control cases. Further, the survival rate of breast cancers during pregnancy and lactation was poorer in the lymph node-positive cases than in the controls. Therefore, we have concluded that pregnancy and lactation promote the progress of a metastatic cancer.