Histologic types of hung carcinoma and age at onset

BACKGROUND. Previous research has demonstrated that adenocarcinoma is the l eading cell type among patients with early age onset lung carcinoma. An inc rease in adenocarcinoma at the expense of squamous cell carcinoma in genera l was observed in recent years and may be due to the smoking of filtered ci garettes. METHODS, To rule out whether shifts in smoking patterns or other etiologic factors are responsible for the high rates of adenocarcinoma in young patie nts, personal interviews regarding smoking, occupation, and family history of cancer were conducted in 251 young patients (age less than or equal to 4 5 years) and 2009 older patients (ages 55-69 years) with histologically con firmed lung carcinoma from selected study clinics in Germany between 1990 a nd 1996. RESULTS. Young male patients were found to have significantly more adenocar cinomas (41%) than older male patients: (28%), whereas adenocarcinomas were dominant in young and older women (43% and 47%, respectively). Because smo king patterns were different between young and older patients, the authors stratified for comparable levels of smoking exposure. Histology did not dif fer in never smokers (dominance of adenocarcinomas in both age groups) and in male heavy smokers (dominance of squamous cell carcinomas in both age gr oups), whereas young male low dose smokers showed significantly more cases of adenocarcinoma than older low dose smokers. A family history of lung car cinoma was significantly higher in young patients compared with older patie nts, but no association with histologic type was observed. CONCLUSIONS. The results of the current study show that differences in the histologic type of lung carcinoma based on age at onset can be explained in part by differences in smoking patterns. However, there still are unknown factors that appear to favor the development of adenocarcinoma in the young . (C) 1999 American Cancer Society.