Multicentricity in nonpalpable breast carcinoma and its implications for treatment.

During a 9 year period, 300 consecutive women underwent breast biopsies solely because of nonpalpable, mammographically suspicous findings. One hundred clinically occult breast carcinomas were found, 65 of which were invasive and 35 noninvasive. Eighty-three mastectomy specimens were evaluable for evidence of multifocal carcinoma in another quadrant of the breast or at a distance of 5 cm and residual cancer outside the excisional biopsy cavity. Multicentricity was present in 47 percent and residual tumor in 60 percent of the whole group. When only clinically occult invasive carcinomas were considered, other foci of invasive carcinoma were demonstrated in 26 percent of the patients and residual invasive cancer in 35 percent. The rate of bilaterality was 14 percent, occurring synchronously in 11 percent of the patients. Any therapeutic procedure for nonpalpable breast carcinoma, whether invasive or noninvasive ductal carcinoma, should be directed to the whole breast. Mammography of the contralateral side should be an integral part of the preoperative work-up of patients with palpable lesions ipsilaterally.