[Multiple primary cancers observed after surgery of lung cancer, and their countermeasures].

Multiple primary cancers were found after surgery in 80 (2.5%) of 3,154 patients with lung cancer. Patients with squamous cell carcinoma most frequently suffered from multiple primary cancers. The period up to discovery of the second primary cancers was within two years in 78.8% of the patients. Second primary cancers were most frequently observed in the lung, followed by the stomach, colon and rectum. Second primary cancers were found in the lung in 26 patients, 14 of these (53.8%) having squamous cell carcinoma. Multiple primary cancers were noted in 2.8% of 1,210 lung cancer patients who underwent stage I curative operation and 2.4% of the remaining 1,944 cases. As to prognosis, 14 patients survived for more than three years after the second primary cancers were found.