Incidence and clinical features of lung cancer in patients with idiopathic interstitial pneumonia

Abstract

We studied the incidence of lung cancer in the 599 patients with idiopathic interstitial pneumonia (IIP) who had visited to 37 institutions during 1991. In addition to 89 patients with lung cancer registered initially 29 were found during more than 4 years of follow-up, which indicates that annual incidence of lung cancer in these patients with IIP was a few percent. A total of 118 lung cancers accounted for 19.7% of all the IIP patients registered and also for 27.2% of the 435 IIP patients in whom a definite outcome was certified by this study. Most of the patients with lung cancer were older men who were heavy smokers. The distribution of histological types was not noteworthy. On the chest rentgenogrms, the tumors were found predominantly in the peripheral lung fields even in the patients with squamous cell cancer, but no apparent association with IIP lesion was observed. Surgical resection was done in only 52% of the patients with the disease at stage I or II; chemotherapy and/or radiotherapy were given to 52.4% of the patients with advanced disease, which may have been due to considerations of the adverse effects of anticancer treatment on the prognoses. The mortality in IIP patients with lung cancer was higher than in those without lung cancer, mainly due to progression of the lung cancer, not the IIP. This indicates the importance of lung cancer as a prognostic factor in patients with IIP.