Urology>>>>>Bladder Cancer
Question 2#

Tobacco smoking is the most wellestablished risk factor for bladder cancer, causing 50%–65% of male cases and 20%–30% of female cases. Which of the following statements regarding smoking and bladder cancer is TRUE?

a. A causal relationship has not been established between an exposure to tobacco and cancer in studies in which chance, bias and confounding factors can be ruled out with reasonable confidence
b. A meta-analysis reporting on pooled risk estimates for current and former smokers demonstrated a significant association with bladder cancer for current smokers only
c. There is no immediate decrease in the risk of bladder cancer in those who stop smoking
d. The promotion of smoking cessation would result in the incidence of bladder cancer decreasing equally in men and women

Correct Answer is D

Comment:

Answer D

Smoking is responsible for 30%–50% of all bladder cancers in males, and smokers have a 2- to 6-fold greater risk of getting bladder cancer. A causal relationship has been established between an exposure to tobacco and cancer in studies in which chance, bias and confounding can be ruled out with reasonable confidence. A meta-analysis looked at 216 observational studies on cigarette smoking and cancer from 1961 to 2003, with reported estimates for current and/or former smokers. The pooled risk estimates for bladder cancer demonstrated a significant association for both current and former smokers. In an analysis of 21 studies, the overall relative risk calculated for current smokers was 2.77, while an analysis of 15 studies showed that the overall relative risk calculated for former smokers was 1.72.

Smoking cessation will decrease the risk of eventual urothelial cancer formation in a linear fashion. After 15 years of not smoking, the risk of cancer formation is the same as for a person who never smoked. The strong influence of smoking in bladder cancer formation prevents accurate determination of other less significant dietary, micronutrient, or lifestyle changes that may alter bladder cancer formation.

An immediate decrease in the risk of bladder cancer is observed in those who stopped smoking. The reduction was about 40% within 1–4 years of quitting smoking.

Further Reading:

  1. Vineis P, Kogevinas M, Simonato L, Brennan P, Boffetta P. Levelling-off of the risk of lung and bladder cancer in heavy smokers: An analysis based on multicentric case-control studies and a metabolic interpretation. Mutat Res 2000; 463(1): 103–110.
  2. Boffetta P. Tobacco smoking and risk of bladder cancer. Scand J Urol Nephrol Suppl 2008; 42(218): 45–54. doi:10.1080/03008880802283664.
  3. IARC Working Group on the Evaluation of Carcinogenic Risks to Humans. Tobacco smoke and involuntary smoking. IARC Monogr Eval Carcinog Risks Hum 2004; 83: 1–1438.
  4. Gandini S, Botteri E, Iodice S, et al. Tobacco smoking and cancer: A meta-analysis. Int J Cancer 2008; 122(1): 155–164.
  5. Brennan P, Bogillot O, Cordier S, et al. Cigarette smoking and bladder cancer in men: A pooled analysis of 11 case-control studies. Int J Cancer 2000; 86(2): 289–294.