Smoking, occupation and family history in lung cancer patients under fifty years of age.

A hospital based case-control study was conducted to investigate the factors affecting the development of lung cancer among young adults. A total of 185 inpatients (males: 128, females: 57) aged from 30 to 49 have been histologically classified in the National Cancer Center Hospital during the last 10 years. Most frequent was adenocarcinoma in both males (57.0%) and females (73.7%). Basic factors were obtained from clinical charts including smoking history, occupation and family history of cancers. Elevated risks were found for squamous cell carcinoma in patients with a history of smoking (all had smoked v. 15/20 for controls) and an occupation possibly related to respiratory irritations (15/20 v. 3/20 for controls). Heavy smokers were distributed more in the cancer patients. Moreover, the average Smoking Index among those without "at risk" occupation was 1,002 with the least being 700, while that with such an occupation was 723. Heavy smoking alone and a smoking/occupation combination could contribute to an early onset of squamous cell carcinoma. On the other hand, there were no significant risk factors for adenocarcinoma, the relative risk from a history of smoking being less than 1.00 and from a family history of cancer, approximately 1.00.