[Descriptive and analytical epidemiology of second primaries in Osaka, Japan]

With the improvement in survival of cancer patients, the incidence of second primaries has been increasing. Data from the Osaka Cancer Registry showed that the incidence of metachronous second primaries was associated with gender (male), age and calendar year at diagnosis of the first cancer. The 10-year cumulative risk was estimated at around 10% for those who developed their first cancer in their sixties in 1978-83. The observed number (O) of second primaries (including synchronous) was compared with the expected number (E). The O/E ratios among those who developed their first cancer at ages 0-14 and 15-29 years old were much higher than the ratios among all age groups. Patients who had developed cancer of the colon, larynx, lung, bladder, or breast (1978-86) showed a significantly higher than expected risk of developing second primaries during the 1-4 years after diagnosis of the first cancer. Based on the hospital cancer registry data from Osaka Medical Center for Cancer and Cardiovascular Diseases, associations between adjuvant chemo-immunotherapy and the risk of second primaries were examined among 1,925 gastric cancer patients who underwent curative gastrectomy. The sex-, age-, and stage-adjusted hazard rate ratio of second primaries was 1.04 for patients who underwent chemotherapy and 0.70 for patients who underwent chemo-immunotherapy, when compared with the risk for patients who did not receive adjuvant chemo-immunotherapy. Some chemotherapeutic agents appeared to increase the risk of second primaries. Second primaries among 2,824 breast cancer patients were examined and their associations with adjuvant chemo-immuno-radiotherapy were analyzed. The O/E ratio for cancers of all sites was 1.28, significantly higher than 1.0. Cancer of the stomach, colon, lung and ovary were frequently observed as a second primary among them. Among 117 patients who developed second primaries, 4 developed cancer of the corpus uteri. This corresponded to 1.89 times the expected, however, only one of the 4 patients underwent tamoxifen treatment. The O/E ratio for non-Hodgkin's lymphoma was 3.40, significantly higher than 1.0. These results suggest associations between the risk for non-Hodgkin's lymphoma and chemotherapy.