[Second malignancies following radiotherapy: an analysis of 54 cases accumulated by mail survey in Japan].

The increasing incidence of second malignant neoplasms after radiotherapy, while due in part to increasing numbers of survivors, is also thought to be related to new modalities of radiotherapy and/or increasingly more intensive combined modality treatment. From a mail survey conducted in 2000 concerning secondary neoplasms following radiotherapy, 62 patients were collected from 22 hospitals in Japan. The following patients were excluded: benign (4 cases) or unknown (2) first primary diseases, unknown histology of a second malignancy (1), and short latent period (from initial radiotherapy to diagnosis of second neoplasm) (1). Fifty-four patients with second malignancies were analyzed. The most common histology of second malignancies was squamous cell carcinoma (24 cases), followed by sarcoma (16), glioma (5), adenocarcinoma (3), leukemia (3), and others (3). The mean latent period was 17.7 (2-38) years. We investigated the correlation of the latent period with patient's characteristics or initial therapeutic factors. Multivariate analysis revealed that the latent period was significantly shortened in patients with combined chemotherapy and radiotherapy.