Four cases of lung cancer associated with idiopathic interstitial pneumonia

It is well known that lung cancer develops frequently in patients with idiopathic interstitial pneumonia (IIP) (9.8-22.8%). We investigated 4 patients who developed lung cancer among the 28 patients with IIP (14.3%) who were admitted to our hospital from June 1981 to March 1989. Many reports have pointed out the clinical features of lung cancer associated with IIP as male sex, old age, heavy smoking, and poor prognosis. Our 4 series were agreed with these clinical features. Lung cancer associated with IIP have been often reported to occur in the lower and peripheral regions of the lung, and honeycomb structures are frequently seen. But we found that lung cancer in IIP could actually occur in both the lower and upper regions of the lung and does not occur only in the honeycomb structures. There was no obvious dominance of any histological type among the tumors. If lung cancer is suspected in a patient with IIP, tumor markers are of some value for diagnosis, but are not sensitive enough to be used alone.