Reproductive factors and risks of biliary tract cancers and stones: a population-based study in Shanghai, China.

BACKGROUND

Parity has been linked to gallbladder cancer and gallstones, but the effects of other reproductive factors are less clear.

METHODS

We examined 361 incident biliary tract cancer cases, 647 biliary stone cases, and 586 healthy women in a population-based study in Shanghai.

RESULTS

The effects of parity (odds ratios, OR(> or =3 vs 1 child)=2.0, 95% confidence interval (CI) 0.7-5.1), younger age at first birth (OR(per 1-year decrease)=1.2, 95% CI 0.99-1.6), and older age at menarche (OR(per 1-year increase)=1.4, 95% CI 1.1-1.8) on gallbladder cancer risk were more pronounced among women with stones, but the interactions were not significant.

CONCLUSION

Our results provide support for high parity, younger age at first birth, and late age at menarche in the development of gallbladder cancer, particularly among women with biliary stones.