Additional malignant neoplasms in patients with breast carcinoma

During a follow‐up of 665 patients with carcinoma of the breast age 40 years or older, 46 developed a second primary carcinoma of the opposite breast and 30 developed a nonmammary malignancy (median FU = 6 yrs). Comparing our number of observed cases with the number of expected cases (calculated from the female age‐specific incidence rate of the data of the Surveillance, Epidemiology and End Results (SEER) and from the actual cumulative person‐years of follow‐up), our patients with breast cancer did not have higher probability of developing additional nonmammary malignancy, but did have over five times the chance of developing a second breast cancer as other females to have any such cancer. Comparing the distribution of specific sites of our nonmammary second cancer with that reported by the SEER's study, the proportions of patients with colorectal, lung cancer, and lymphoma were similar. But we did see relatively more carcinomas of the uterine cervix, ovary, vulva, sarcoma, and stomach/duodenum, and fewer carcinoma of the endometrium. These differences could be explained by our small series, patient characteristics, and selected referral pattern.