Studies on the pathogenesis of lung cancer with interstitial pneumonia Part 1. Analysis of the clinical features of intersitial pneumonia in lung cancer

Clinical features and findings on chest x-ray were analyzed to clarify the relationship between lung cancer and interstitial pneumonia. Of 262 patients with lung cancer, 69 patients (26.3%) had interstitial pneumonia. Patients with interstitial pneumonia (LC with IP) were older than those without interstitial pneumonia (LC without IP). The incidence of LC with IP cases among males and smokers were 29.2% and 29.3%, respectively. There were no significant differences among histlogic types and clinical stages of lung cancer. More cases of LC with IP had cancer in the lower (42.0%) and peripheral (76.8%) areas on chest x-ray films. Cancer was frequently located within the interstitial shadow on chest x-ray film. Among 40 patients with idiopathic interstitial pneumonia associated lung cancer (IIP with LC), there were 38 males and 32 smokers. No dominant histlogic subtype of lung cancer was noted in IIP with LC, though the most frequent was adenocarcinoma (16 cases, 40%). In IIP with LC, the site of cancer was associated with active fibrotic changes in interstitial pneumonia. These data strongly suggest that carcinogenic factors were related to the fibrotic changes in interstitial pneumonia.