The impact of smoking on survival in renal cell carcinoma: a systematic review and meta-analysis

Epidemiological evidence suggests that cigarette smoking is the best-established risk factor for renal cell cancer (RCC). However, the effect of smoking on survival of RCC patients remains debated. We therefore conducted a meta-analysis to investigate the impact of smoking status on overall mortality (OM), disease-specific mortality (DSM), overall survival (OS), cancer-specific survival (CSS), and progression-free survival (PFS) in patients with RCC. We searched Medline, Embase, and the Cochrane Central Search Library for published studies that analyzed the effect of smoking on survival or mortality of RCC. We selected 14 articles according to predefined inclusion criteria. The smoking status was categorized into never smokers and ever smokers (former smokers and/or current smokers). Summary hazard ratios (HRs) with 95 % confidence intervals (CIs) were calculated with a fixed or random effects model. Overall, 14 studies including 343,993 RCC cases were accepted for meta-analysis. Ever smoking was significantly correlated with OM (HR 1.30, 95 % CI 1.07-1.58), while no associated with poorer DSM (HR 1.23, 95 % CI 0.96-1.57). Further analysis found current (HR 1.57, 95 % CI 1.20-2.06) but not former smoking (HR 1.14, 95 % CI 0.79-1.63) was associated with a significantly increased risk of OM. Meanwhile, current smoking was associated with poorer DSM (HR 1.50, 95 % CI 1.10-2.05) in subgroup analysis. Ever smoking was significantly associated with poorer OS (HR 1.45; 95 % CI 1.00-2.09) and poorer CSS (HR 1.01; 95 % CI 1.00-1.02), compared with never smokers. Current smoking was associated with poorer PFS (HR 2.94, 95 % CI 1.89-4.58). This review provides preliminary evidence that current smoking in a patient with RCC is associated with poorer survival, demonstrating active smoking to be an independent risk for prognosis of RCC. Smoking cessation should be recommended for RCC patients.