Comparative Analysis of Smoking as a Risk Factor among Renal Cell Carcinoma Histological Subtypes.

ABSTRACT

PURPOSE: Smoking is the best established modifiable risk factor for renal cell carcinoma. However, the risks of individual renal cell carcinoma histological subtypes are unknown. Therefore, we investigated the relationship between smoking and renal cell carcinoma subtype. MATERIALS AND METHODS: Cigarette smoking data were prospectively collected from 816 consecutive patients with nonfamilial renal cell carcinoma (705) or benign pathology (111) undergoing nephrectomy at a single National Comprehensive Cancer Network® cancer center, and were retrospectively tested for an association with histological diagnosis on univariable and propensity adjusted analyses. RESULTS: Smoking was reported by 51% of patients, including 21% active smokers and 30% former smokers. Active smoking was more common with clear cell (23%) or papillary (26%) renal cell carcinoma than benign histology (14%, p <0.05 each), yet strikingly less common with chromophobe renal cell carcinoma (6%, p <0.05 vs clear cell or papillary). Any smoking history (active or former) was also relatively uncommon with chromophobe (26%) vs clear cell (53%, p = 0.003) or papillary (58%, p = 0.001) histology. Smoking extent based on mean pack-years was significantly greater with clear cell (15.3 mean pack-years) or papillary (15.2 mean pack-years) renal cell carcinoma but not chromophobe renal cell carcinoma (9.4 mean pack-years) compared to benign histology (9.4 mean pack-years, p ≤0.05, p <0.05, p = 1.0, respectively). On propensity analyses adjusting for multiple variables, clear cell (OR 2.2, p <0.05) and papillary (OR 2.4, p <0.05) histologies but not chromophobe histology remained independently associated with active smoking. CONCLUSIONS: Traditional understanding of smoking as a renal cell carcinoma risk factor applies to clear cell and papillary renal cell carcinoma but not the chromophobe subtype. These findings underscore distinct carcinogenic mechanisms underlying the various renal cell carcinoma subtypes.