Clinical Study of Multiple Primary Lung Cancers

In our department 39 patients (2.02% of all patients treated for primary lung cancer) were diagnosed as multiple primary lung cancer (MPLC) between January 1977 and March 1991. In 18 of these MPLC cases both lesions were judged to be stage I. (We call such cases stage I MPLC.) Combination with mass surveys including chest X-ray and sputum cytology, and periodical detailed examinations of patients with primary lung cancer (PLC) increased the rate of relatively early detected cases. The 5-year survival of cases with synchronous disease was 45.1%. In metachronous disease the rates after the detection of the first cancer and after that of the second cancer were 70.6% and 46.9%, respectively. In stage I MPLC case the 5-year survival rate for synchronous disease was 80.0%, and the rates for metachronous disease after the initial detection and after the development of a metachronous lesion were 71.4% and 66.7%, respectively. No statistical difference was observed between stage I MPLC cases and stage I PLC cases in 5-year survival. The prognosis of MPLC is not very bad, when the lesion is discovered at an early stage.