Relationship between N-nitrosodimethylamine and risk of urogenital cancers: a Meta-analysis based on cohort studies

Objective To analyze the relationship between N-nitrosodimethylamine(NDMA) and the risk of urogenital cancers by means of Meta-analysis based on cohort studies. Methods The cohort studies on the carcinogenic NDMA and occurrence/dead risk of malignancy of genitourinary system among population that published in journals from 1980 to 2014 were identified from the following databases:the Chinese Journal Full-text Database(CNKI),Chinese BioMedical Literature Database(CBM),Wanfang Database,PubMed and EBSCO.The fix and random effects model was employed and statistical analysis is conducted using RevMan 5.1 software. Results A total of 13 studies were found,of which 7 articles including urogenital cancers were included in the Meta analysis.There was significant correlation between NDMA and all kinds of cancer(RR=1.17,95%CI 1.02-1.34).The NDMA did not have positive effect with urogenital cancers(RR=0.99,95%CI 0.95-1.03).There was not significant positive correlation between NDMA and prostate cancer(RR=0.97,95%CI 0.92-1.03) and ovarian cancer(RR=0.87,95%CI 0.69-1.08),but NDMA could increase the risk of breast cancer without significance(RR=1.03,95%CI 0.94-1.12).However,the NDMA had positive effect with bladder cancer(RR=1.26,95%CI 1.01-1.57). Conclusion The population cohort studies have showed that the NDMA would not significantly increase the risk of urogenital cancers,but had different effect with different types.It is essential to accumulate evidence derived from population cohort studies to prove the correlation.