Association of smoking status with prognosis in bladder cancer: A meta-analysis

There is considerable controversy regarding the association between smoking and prognosis in surgically treated bladder cancer. The present meta-analysis was performed to quantify the role of smoking status in bladder cancer recurrence, progression and patient survival by pooling the available previous data. Pubmed, Embase and the Cochrane Library databases were searched for eligible studies published prior to April 2016. Random and fixed effects models were used to calculate the summary relative risk estimates (SRRE). A total of 10,192 patients from 15 studies were included in the meta-analysis. There was evidence of positive associations between current smoking and the risk of recurrence (SRRE=1.23; 95% CI, 1.05-1.45) and mortality (SRRE=1.28; 95% CI, 1.07-1.52) in bladder cancer. Furthermore, former smoking had positive associations with bladder cancer recurrence (SRRE=1.22; 95% CI, 1.09-1.37) and mortality (SRRE=1.20; 95% CI, 1.03-1.41). However, there was no significant association between bladder cancer progression risk and current (SRRE=1.11; 95% CI, 0.71-1.75) or previous smoking (SRRE=1.16; 95% CI, 0.92-1.46). The findings indicate that current and former smoking increase the risk of recurrence and mortality in patients with bladder cancer. However, due to the nonrandomized and retrospective nature of the current study, patients may be prone to potential selection bias. Prospective and larger epidemiological studies with a longer follow-up are required to confirm these findings.