The data of an epidemiologic study of multiple primary malignant neoplasms in breast cancer patients in Israel are presented. During the 18-year period of the study 12,302 cases of breast carcinoma were diagnosed, and, of these, 984 patients (8%) had multiple primary malignant tumors. Forty-seven of these patients developed two multiple primary cancers. A significantly higher than expected incidence of second primary cancers occurred at the following five sites: the opposite breast, salivary glands, uterine corpus, ovary, and thyroid. Cancers of the stomach and gallbladder were fewer than expected. Treatment of the breast cancer by irradiation was associated with an increased risk of subsequent cancers of lung and hematopoietic system. The prognosis was mainly influenced by the site and malignancy of the second primary cancer. The incidence of multiple primary malignancies justifies a high level of alertness to this possibility in the follow-up of breast cancer patients.
Cancer 54:145-150, 1984.
ULTIPLE PRIMARY MALIGNANT NEOPLASMS seem
M to be increasing in frequency.' This may have come about with improved clinical awareness, the possible effect of new environmental carcinogenic forces, the increased use of chemotherapeutic agents which are themselves carcinogens, and, to some extent, the increased longevity of cancer patients which enables them to live long enough to develop a second primary cancer. The criteria for diagnosing multiple primary tumors are: (1) each of the tumors must present a definite picture of malignancy; (2) each must be distinct and (3) the probability that one was a metastatic lesion from the other must be excluded.2
When discussing multiple primary cancer, it is clinically important to ascertain whether the patient with an initial cancer has an increased, decreased, or unchanged risk of developing a second cancer.
Breast carcinoma is the most prevalent malignancy in Israeli women, and as such it poses a great clinical problem; we therefore chose to study multiple primary malignancies in this population. This study was designed to evaluate the extent of occurrence of second primary cancers in breast cancer patients and to evaluate the relative risks of developing the additional cancers at the different anatomic sites. This data together with additional clinical