Long-term follow-up of in situ carcinoma of the breast with special emphasis on clinging carcinoma.

Forty-two cases of in situ duct (28 cases) and lobular (14 cases) carcinoma were identified after a review of 4,397 "benign" breast biopsies obtained from the files of departments of pathology of a small area of Northern Italy, between 1965 and 1971. None of the patients with in situ lobular carcinoma developed an invasive carcinoma. On the other hand, three patients with in situ duct carcinoma (one comedo and two clinging type) developed subsequent invasive carcinoma. Therefore, it appears that clinging carcinoma has the same biological behavior as other types of small in situ ductal carcinoma; the likelihood of our patients developing invasive breast carcinoma is four times greater than that of the general population.