Opium consumption and risk of bladder cancer: A case-control analysis.

OBJECTIVE

We evaluated the relationship between opium consumption and bladder cancer (BC) in a case-control study of an Iranian population.

METHODS

In a hospital-based case-control study of 179 patients with BC and 179 cancer-free controls frequency-matched by age, sex, and smoking status, we investigated the relationship between opium consumption and BC. A comprehensive epidemiologic interview was conducted on all participants to collect personal information, such as demographics and smoking status.

RESULTS

Overall, we found significant age, sex, cigarette smoking adjusted association between BC risk and opium consumption, [odds ratio (OR) = 4.60; 95% confidence interval (CI) = 3.53-6.28]. The elevated risk was more evident in older individuals (OR = 5.42; 95% CI, 4.12-7.28) than younger individuals (OR = 3.65; 95% CI, 2.76-4.76) (P = 0.01). Heavy smokers with the opium consumption exhibited a 6-fold elevated risk for BC (OR = 6.16; 95% CI, 3.34-8.32) (P = 0.0001). When stratified according to different grades of BC, a 3.4-fold increased risk was associated with the opium consumption in grade III with an OR of 3.44 (95% CI, 2.82-8.28) (P = 0.001). A similar but slightly higher risk was also seen in case of grade IV tumors (OR = 3.86; 95% CI, 2.14-10.16) (P = 0.001). Invasive bladder tumors were more common among the opiates users (OR = 2.6; 95% CI, 1.44-5.42) (P = 0.01). Cumulative risk of BC in women with opium consumption (OR = 4.10 95% CI, 3.54-5.88) (P = 0.001) was slightly less than in men (OR = 5.10 95% CI, 3.54-5.88) (P = 0.0001). Based on Pearson correlations, the risk of BC significantly correlated with opium dependence duration (r = 0.74, P = 0.001), type of opiate used (r = 0.65, P = 0.001), and simultaneous cigarette smoking (r = 0.74, P = 0.0001).

CONCLUSIONS

The results indicated that there is about 5-fold increase in risk of developing this cancer in the presence of opium consumption. Further research is needed to investigate the functional implications of the opium consumption in BC.