The relationship between smoking habits and the risk of renal cell carcinoma was investigated in a case-control study conducted in northern Italy on 131 cases of histologically confirmed cancers of the renal parenchyma (85 males, 46 females) and 394 controls in hospital for acute, nonneoplastic, nonurological disorders. Compared with never smokers, the relative risk (RR) was 1.7 (95% confidence interval = 1.0–3.1) among ex-smokers. A direct and significant dose-risk relationship was observed among current smokers, with RR of 1.1, 1.9, and 2.3 for moderate, intermediate, and heavy smokers. This trend in risk was statistically significant (x21 = 5.04; P = 0.02). The risk was directly related with duration of smoking (RR = 1.7 for <30 versus 1.8 for ≥30 years, P = 0.04), and inversely with age at starting (RR = 2.0 for ≤20 versus 1.7 for >20 years) and, among ex-smokers, with time elapsed since stopping (RR = 2.2 for <10 versus 1.3 for ≥10 years). This pattern of risk, together with the absence of appreciable confounding, adds further evidence for a causal nature of the association between smoking and renal cell cancer.
This work was conducted within the framework of the National Research Council (CNR), Applied Projects “Oncology” (Contract 87.01544.44) and “Risk Factors for Disease,” and with the contribution of Italian Association for Cancer Research and the Italian League against Tumors, Milan.