Does increased urination frequency protect against bladder cancer?

Experimental studies suggest that increased urination frequency may reduce bladder cancer risk if carcinogens are present in the urine. Only 2 small studies of the effect of increased urination frequency on bladder cancer risk in humans have been conducted with conflicting results. Our purpose was to evaluate the effect of urination frequency on risk of bladder cancer in a large, multicenter case-control study. We analyzed data based on interviews conducted with 884 patients with newly diagnosed, bladder cancer and 996 controls from 1998 to 2001 in Spain. We observed a consistent, inverse trend in risk with increasing nighttime voiding frequency in both men (p = 0.0003) and women (p = 0.07); voiding at least 2 times per night was associated with a significant, 40-50% risk reduction. The protective effect of nocturia was apparent among study participants with low, moderate and high water consumption. The risk associated with cigarette smoking was reduced by nocturia. Compared with nonsmokers who did not urinate at night, current smokers who did not urinate at night had an OR of 7.0 (95% CI = 4.7-10.2), whereas those who voided at least twice per night had an OR of 3.3 (95% CI = 1.9-5.8) (p value for trend = 0.0005). Our findings suggest a strong protective effect of nocturia on bladder cancer risk, providing evidence in humans that bladder cancer risk is related to the contact time of the urothelium with carcinogens in urine. Increased urination frequency, coupled with possible dilution of the urine from increased water intake, may diminish the effect of urinary carcinogens on bladder cancer risk.
AuthorsDebra T Silverman, Juan Alguacil, Nathaniel Rothman, Francisco X Real, Montserrat Garcia-Closas, Kenneth P Cantor, Nuria Malats, Adonina Tardon, Consol Serra, Reina Garcia-Closas, Alfredo Carrato, Josep Lloreta, Claudine Samanic, Mustafa Dosemeci, Manolis Kogevinas
JournalInternational journal of cancer. Journal international du cancer (Int J Cancer) Vol. 123 Issue 7 Pg. 1644-8 (Oct 1 2008) ISSN: 1097-0215 [Electronic] United States
PMID18623081 (Publication Type: Journal Article, Multicenter Study, Research Support, Non-U.S. Gov't)
Chemical References
  • Carcinogens
  • Adult
  • Aged
  • Aged, 80 and over
  • Carcinogens (analysis)
  • Case-Control Studies
  • Female
  • Humans
  • Male
  • Middle Aged
  • Smoking (urine)
  • Urinary Bladder Neoplasms (prevention & control)
  • Urination

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