Background: The tendency for breast cancer to form multiple lesions is important to consider when planning breast-conserving surgery. However, many unknowns remain regarding the pathology and prognosis of multiple breast cancer, and therefore it is clinically significant to investigate its clinicopathological properties.
Methods: Over the past 25 years, in the period between April 1972 and March 1997, we investigated the clinicopathological findings including the 5-year and 10-year survival rates of 66 patients treated for unilateral multiple breast cancer.
Results: Of the total of 1,334 female patients with unilateral breast cancer who underwent curative surgery at our hospital, we identified 66 (5.0%) patients with unilateral multiple cancer. The incidence of such cancer has been higher in recent years. Of the 66 patients, 50 (75.8%) were premenopausal, and the remaining patients were postmenopausal, but multiple cancer among postmenopausal women is a recent phenomenon. The ER positivity rate of the main lesion in patients with multiple breast cancer was 69.2% and that of PgR was 50.0%. The 5-and 10-year overall survival rate in all 66 patients with multiple breast cancer was 90.8% and 79.7%, respectively.
Conclusion: In the past, multiple breast cancer was frequently identified in premenopausal women. However, the current findings indicate that its incidence among postmenopausal women has increased in recent years. In addition, prognoses were comparable for patients with multiple or solitary breast cancer, a relevant finding in the planning of breast-conserving surgery.