the risk of cancer among Taiwanese female registered nurses: a nationwide retrospective study.

BACKGROUND: To evaluate the risk of cancer among Taiwanese female registered nurses (RNs) using a nationwide population-based dataset. METHODS: We recruited female RNs without antecedent cancer from the Taiwan National Health Insurance Research database during 2000-2010. Standardized incidence ratios (SIRs) of cancer were calculated. We also compared rates of Papanicolaou (Pap) smear use between the RNs and the general population matched by age and sex. RESULTS: A total of 2,077 cancers developed among 184,809 female RNs, with a follow-up of 1,371,910 person-years (median follow-up of 7.86 years), leading to an increased SIR of 1.10 [95% confidence interval (CI) 1.05-1.15]. RNs aged between 40-59 years also had a significantly increased SIR (1.14, 95% CI 1.08-1.21). For specific cancer types, RNs had an increased SIR for breast (1.28, 95% CI 1.19-1.37), thyroid (1.26, 95% CI 1.10-1.43), lung and mediastinum (1.36, 95% CI 1.13-1.62), and uterine cancers (1.23, 95% CI 1.01-1.49). A decreased SIR was found for cervix (0.48, 95% CI 0.37-0.61) and liver and biliary tract cancers (0.68, 95% CI 0.50-0.90). Pap smear use averaged 5.80 times per person among female RNs aged 35 years or older and 5.50 times per person in the age-matched control group (p = 0.009). CONCLUSION: This study found that overall cancer risk was higher among female RNs than general population. For individual cancers, the risks of breast, lung, thyroid and uterine cancer were higher and the risks of cervix and liver cancer were lower than general population. The lower risk of cervical cancer might be partially explained by the increased use of Pap smears in the RNs group. Further large, unbiased population-based prospective studies are needed to investigate the association between nurses and cancer risk and identify the risk factors of cancer in nurses.