Vitamin A and lung cancer.

Retrospective dietary and smoking data were gathered by interview of 292 white male patients with lung cancer and 801 control patients with nonrespiratory, nonneoplastic diseases at Roswell Park Memorial Institute, Buffalo, New York. A computed index of vitamin A intake was used to differentiate lung cancer patients from controls. Lung cancer patients had lower values than did controls. The reduced relative risk (RR) of lung cancer associated with vitamin A was most evident among men who smoked heavily. For them, a dose-response relationship increasing to an RR of 2.4 for low values of the index was observed. Frequency of daily milk drinking was lower among patients with lung cancer. Lower RR was found among the men who smoked heavily and frequently consumed carrots. These findings are consistent with evidence from animal studies on inhibition of tumor incidence by retinoids and with previous findings in prospective and retrospective epidemiologic studies.