The prognosis of lung cancer originating as an infiltrate. Data from the Philadelphia Pulmonary Neoplasm Research...

In a periodic screening study of 6,027 older men, 121 developed lung cancer during the 10 yr of observation. The over-all 5-yr survival rate was 8%, but when the 121 men were subdivided according to the initial radiographic appearance of cancer, a group of 23 with ill-defined peripheral lesions that we labeled "infiltrates" had the best prognosis over the first 5 yr of follow-up. This advantage tended to disappear thereafter. The men whose tumors originated as infiltrates also had the highest resection rate and were detected most frequently within 7.5 months of a negative film. The infiltrates tended to be smaller than the well-defined peripheral tumors that we designated round lesions. In 8 of 13 instances with radiographic follow-up, the infiltrates assumed the appearance of round lesions or irregular masses. These observations suggested that the infiltrate is often a biologically earlier lesion than other radiographic forms of lung cancer.