Bladder cancer modifiable risk factors include low vitamin D – meta-analysis March 2016

Modifiable risk factors for the prevention of bladder cancer: a systematic review of meta-analyses.

Eur J Epidemiol. 2016 Mar 21.
Al-Zalabani AH1, Stewart KF2, Wesselius A3, Schols AM4, Zeegers MP3.

• 1 Department of Family and Community Medicine, College of Medicine, Taibah University, P.O. Box 42317, Madinah, 41541, Saudi Arabia.
• 2 Department of Complex Genetics, School of Nutrition, and Translational Research in Metabolism (NUTRIM), Maastricht University Medical Centre, P. O. Box 616, 6200 MS, Maastricht, The Netherlands. k.stewart at maastrichtuniversity.nl.
• 3 Department of Complex Genetics, School of Nutrition, and Translational Research in Metabolism (NUTRIM), Maastricht University Medical Centre, P. O. Box 616, 6200 MS, Maastricht, The Netherlands.
• 4 Department of Respiratory Medicine, School of Nutrition and Translational Research in Metabolism (NUTRIM), Maastricht University Medical Centre, P. O. Box 616, 6200 MS, Maastricht, The Netherlands.

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Each year, 430,000 people are diagnosed with bladder cancer. Due to the high recurrence rate of the disease, primary prevention is paramount. Therefore, we reviewed all meta-analyses on modifiable risk factors of primary bladder cancer. PubMed, Embase and Cochrane database were systematically searched for meta-analyses on modifiable risk factors published between 1995 and 2015. When appropriate, meta-analyses (MA) were combined in meta-meta-analysis (MMA). If not, the most comprehensive MA was selected based on the number of primary studies included. Probability of causation was calculated for individual factors and a subset of lifestyle factors combined. Of 1496 articles identified, 5 were combined in MMA and 21 were most comprehensive on a single risk factor. Statistically significant associations were found for

• current (RR 3.14) or former (RR 1.83) cigarette smoking,
• pipe (RR 1.9) or cigar (RR 2.3) smoking,
• antioxidant supplementation (RR 1.52),
• obesity (RR 1.10),
• higher physical activity levels (RR 0.86),
• higher body levels of selenium (RR 0.61) and
• vitamin D (RR 0.75), and
• higher intakes of: processed meat (RR 1.22),
• vitamin A (RR 0.82),
• vitamin E (RR 0.82),
• folate (RR 0.84),
• fruit (RR 0.77), v
• egetables (RR 0.83),
• citrus fruit (RR 0.85), and
• cruciferous vegetables (RR 0.84).

Finally, three occupations with the highest risk were tobacco workers (RR 1.72), dye workers (RR 1.58), and chimney sweeps (RR 1.53). The probability of causation for individual factors ranged from 4 to 68 %. The combined probability of causation was 81.8 %. Modification of lifestyle and occupational exposures can considerably reduce the bladder cancer burden. While smoking remains one of the key risk factors, also several diet-related and occupational factors are very relevant.

PMID: 27000312