Bilateral and multifocal breast carcinoma. A clinical and autopsy study with special emphasis on carcinoma in situ

Bilateral clinical breast carcinoma has been reported to appear in up to approximately 10% of patients with breast carcinoma. Increasing diagnostic activity has raised figures of bilaterality, mainly due to detection of lesions of the in situ type. Knowledge of the natural history of carcinoma in situ is incomplete and clinical implications are uncertain. In the present study bilateral lesions were analysed by extensive histological examination in the following groups of patients: (1) Forty-six women (median age 44 years) with clinical and mammographical unilateral invasive breast carcinoma, where the contralateral breast was removed at subcutaneous mastectomy (SCM) during the course of breast reconstruction, 24/46 (52%) had bilateral malignant lesions, four invasive carcinomas and 20 in situ carcinomas (two ductal carcinomas in situ /DCIS/, 15 lobular carcinomas in situ (LCIS), three both DCIS and LCIS). (2) Fifty-two women (median age 50 years) with a unilateral diagnosis of in situ carcinoma (32 DCIS, 16 LCIS, four both DCIS and LCIS), in whom both breasts were removed at SCM. 25/52 (48%) had bilateral malignant lesions, one invasive carcinoma, 24 in situ carcinomas (three DCIS, 18 LCIS, three both DCIS and LCIS). Twelve of 20 cases with LCIS (60%) were bilateral. Of 36 cases with DCIS, seven (19%) were bilateral. (3) The contralateral breast was removed at autopsy in 64 women previously unilaterally mastectomized (at median age 65) for invasive breast carcinoma. Fifteen of 64 (23%) had contralateral primary carcinoma at autopsy, four invasive carcinomas, 11 in situ carcinomas (six DCIS, five LCIS) and 8/64 (13%) had metastases in the breast. Multifocal malignant findings were also analysed in 47 SCM specimens after excisional biopsy for in situ carcinoma. In 35/47 (75%) further malignant lesions were present in spite of normal mammographic and clinical findings. Four were invasive and 31 had in situ lesions (16 DCIS, 10 LCIS, five both DCIS and LCIS): These findings may favour the hypothesis that some carcinomas in situ may remain silent or even regress. It is thus important to embark upon randomized trials to clarify the natural history of breast carcinoma in situ. Such a trial has been started in the southern region of Sweden.