Incidence and risk factors for second breast primaries in women with lobular breast carcinoma

Seven hundred five women with either in situ or invasive lobular breast carcinoma were identified through the British Columbia Cancer Registry; 220 were followed for at least 5 years. 2.3% were found to have synchronous (diagnosed within 1 month of the first primary) bilateral breast cancer; the incidence of asynchronous (diagnosed after 1 month) invasive bilateral breast cancer was 0.9 per 100 women - years. Family history of breast cancer, parity, and nodal status at time of diagnosis of the first primary were examined as risk factors for synchronous breast cancer, and none were significant. Of the risk factors examined for asynchronous invasive second primaries, only positive nodal status was significantly related to risk. The risk factors for bilateral breast cancer in women with lobular carcinoma differed from those in women with ductal carcinoma as reported in the literature.