Cigarette Smoking and other Risk Factors for Kidney Cancer Death in a Japanese Population: Japan Collaborative Cohort Study for Evaluation of Cancer Risk (JACC study)

Background: Cigarette smoking is the largest single recognized cause of human cancers. In Western countries,many epidemiologists have reported risk factors for kidney cancer including smoking. However, little is knownabout the Japanese population. Materials and
Methods: We evaluated the association of smoking with the riskof kidney cancer death in the Japan Collaborative Cohort (JACC) Study. Participants included 46,395 malesand 64,190 females. The Cox proportional hazards model was used to determine age-and-sex adjusted relativerisks.
Results: A total of 62 males and 26 females died from kidney cancer during the follow-up of 707,136and 1,025,703 person-years, respectively. Heavy smokers (Brinkman index >1200), fondness of fatty foods,hypertension, diabetes mellitus (DM), and obesity were suggested to increase the risk of renal cell carcinomawhile walking was suggested to decrease the risk. Even after controlling for age, sex, alcohol drinking and DM,heavy smoking significantly increased the risk.
Conclusions: The present study suggests that six factors includingsmoking may increase and/or reduce the risk of kidney cancer in the Japanese population. Because of the smallnumber of outcomes, however, we did not evaluate these factors after adjusting for all possible confoundingfactors. Further studies may be needed to confirm the findings in this study.