Arguments against routine contralateral mastectomy or undirected biopsy for invasive lobular breast cancer

Background. Management of the contralateral normal-appearing breast in a patient with ipsilateral invasive lobular carcinoma (ILC) is controversial. Methods. The case histories of patients with histologically proven ILC who underwent definitive surgery at our institution from 1978 to 1991 were retrospectively reviewed. Results. Of the 419 women, with ILC, 36 (8.6%) had bilateral cancer, with a cumulative risk of 10% at 10 years. Twenty-flue (69%) of these cancers were suspected before operation. From 105 contralateral prophylactic surgical procedures, seven (64%) in-situ and four (36%) invasive cancers were detected. The age at presentation and multifocality of the index cancer were significantly different between patients with unilateral and those with bilateral cancers. No survival difference was noted between patients whose contralateral cancers were suspected clinically and those whose cancers were detected prophylactically. Survival rates between patients with unilateral versus bilateral cancers were also not different. However, patients with contralateral prophylactic surgery had a better prognosis than those with unilateral tumors and no prophylaxis. Conclusions. Ten percent of patients with ILC experienced bilateral cancers during a period of 10 years. Survival was not influenced by the development of a second cancer, but it improved with surgical prophylaxis.