Second primary lung cancer: importance of long term follow up.

Review of histopathological and clinical data showed that 153 patients at one hospital developed a second primary lung cancer during 1980-6, 10% of all those with lung carcinoma. There were 64 synchronous tumours (interval less than one year) and 89 metachronous tumours (interval over one year). The average interval between metachronous tumours was 6.1 years. The criteria for diagnosing a second primary lung cancer were any of the following: (1) different histological type; (2) different lobe; (3) interval between the two tumours of at least three years. The incidence of second primary tumours increases with survival, and close follow up is required for their early detection.