Nested Case-control Study of Occupational Radiation Exposure and Breast and Esophagus Cancer Risk among Medical Diagnostic X Ray Workers in Jiangsu of China.

Medical diagnostic X-ray workers are one occupational group that expose to the long-term low-dose external radiation over their working lifetime, and they may under risk of different cancers. This study aims to determine the relationship between the occupational X-ray radiation exposure and cancer risk among these workers in Jiangsu, China. We conducted Nested case-control study to investigate the occupational X-ray radiation exposure and cancer risk. Data were collected through self-administered questionnaire, which includes but not limits to demographic data, personal behaviors and family history of cancer. Retrospective dose reconstruction was conducted to estimate the cumulative doses of the x-ray workers. Inferential statistics, t-test and 2 tests were used to compare the differences between each group. We used the logistic regression model to calculate the odds ratio (OR) and 95% confidence interval (CI) of cancer by adjusting the age, gender. All 34 breast cancer cases and 45 esophageal cancer cases that detected in a cohort conducted among health workers between 1950~2011 were included in this presented study, and 158 cancer-free controls were selected by frequency-matched (1:2). Our study found that the occupational radiation exposure was associated with a significantly increased cancer risk compared with the control, especially in breast cancer and esophageal cancer (adjusted OR=2.90, 95% CI: 1.19-7.04 for breast cancer; OR=4.19, 95% CI: 1.87-9.38 for esophageal cancer, and OR=3.43, 95% CI: 1.92-6.12 for total cancer, respectively). The occupational X-ray radiation exposure was associated with increasing cancer risk, which indicates that proper intervention and prevention strategies may be needed in order to bring down the occupational cancer risk.

[Relationship between polymorphisms of X-ray repair cross-complementing group 1 gene Arg194Trp, Arg399Gln and susceptibility of breast cancer].

OBJECTIVE: To study the relationship between two polymorphisms, Arg194Trp and Arg399Glu, of DNA repair gene X-ray repair cross-complementing group 1 (XRCC1) and the susceptibility of breast cancer in Chinese women. METHODS: A case-control study with 698 histologically-confirmed female breast cancer cases and 813 cancer-free controls frequency-matched by age and residential area was conducted, and the genotypes were determined by the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) assays. Logistic regression analysis was used to evaluate the odds ratios (ORs) and 95% confidence intervals (CIs) of XRCC1 Arg194Trp and Arg399Glu with susceptibility of breast cancer. A Meta-analysis was used to evaluate the association of Arg399Glu with breast cancer in Chinese women. RESULTS: The genotype frequencies of Arg/Arg, Arg/Trp, Trp/Trp, Arg/Trp + Trp/Trp of XRCC1 gene 194 locus were 48.81% (327/670), 39.85% (267/670), 11.34% (76/670), 51.19% (343/670) in cases and 48.80% (387/793), 41.99% (333/793), 9.21% (73/793), 51.20% (406/793) in controls. Compared to Arg/Arg, the adjusted ORs (95%CIs) were 0.98 (0.75 - 1.28), 1.17 (0.76 - 1.80), 1.09 (0.86 - 1.40). The frequencies of Arg/Arg, Arg/Trp, Trp/Trp, Arg/Gln + Gln/Gln of XRCC1 399 locus were 52.40% (349/666), 38.29% (255/666), 9.31%(62/666), 47.60% (317/666) in cases and 52.22% (412/789), 38.53% (304/789), 9.25% (73/789), 47.78%(377/789) in controls. Compared to Arg/Arg, the adjusted ORs (95%CIs) were 0.93(0.63 - 1.08), 0.96 (0.42 - 1.09), 0.91 (0.62 - 1.05). No significant associations were found between these two polymorphisms and breast cancer risk, also in subgroups stratified by menopause status, history of breast-feed, reproduction and taking oral contraceptives. The overall ORs (95%CIs) of 399 Arg/Trp + Trp/Trp vs Arg/Arg from Meta analysis was 0.97 (0.85 - 1.10). CONCLUSION: The XRCC1 Arg194Trp and Arg399Gln may not play an important role in the susceptibility of breast cancer in Chinese women.