[Double cancer in small cell lung cancer patients treated with intensive chemotherapy with or without radiation therapy].

Development of double cancer was evaluated in 311 small cell lung cancer patients who had received intensive chemotherapy with or without radiotherapy. Of those, 10 patients (3.2%) developed a second malignancy:stomach cancer in four, non-small cell lung cancer in three, acute myelogenous leukemia in two, and liver cancer in one. The cumulative risk for the development of double cancer was 1.0% at 1-year, 17.0% at 3-years, and 100% at 8.1 years. The relative risk for the development of double cancer calculated by person-year method utilizing age and sex adjusted cancer incidence in Japan was 2.96-fold (p less than 0.01). The risk of non-small cell lung cancer (6.65-fold) and acute myelogenous leukemia (54.9-fold) was particularly high. Of 21 patients who survived disease-free for more than 2 years, 8 patients died; four patients (50%) died of second malignancy, two died of infectious disease, and only two patients died from recurrent small cell lung cancer. These results indicate that a cautious follow-up program for the detection of double cancer is indicated in patients surviving small cell lung cancer.