Summary
Interest in the presence and management of synchronous multiple ipsilateral breast cancer has been reported since the early 1920s. The demonstration of multiple foci of breast cancer has been reported in 9–75% of breast cancer related specimens. The large difference in reported incidence is multifactorial and related to the definitions applied, mode of detection and pathological assessment. However, randomised clinical trials comparing total mastectomy and segmental mastectomy with or without radiation over many years have shown no difference in distant disease-free survival or overall survival in patients with synchronous multiple ipsilateral breast cancer compared with unifocal breast cancer. This review examines the current definitions, incidence, pathological assessment, staging and surgical options of synchronous multiple ipsilateral breast cancer.