Use of oral contraceptives, intrauterine devices and tubal sterilization and cancer risk in a large prospective study, from 1996 to 2006.
The association of contraceptive methods, including oral contraceptives (OC), intrauterine devices (IUD) and tubal sterilization (TS), with overall and site-specific cancer were prospectively investigated in a cohort of 66,661 Chinese women in Shanghai, 76.7% of whom used contraception. During a median follow-up time of 7.5 years, 2,250 women were diagnosed with cancer. Ever-use of any contraceptive method was not associated with overall cancer risk [adjusted hazard ratio (HR(adj)) = 1.02, 95% CI, 0.92-1.12]. Use of any contraceptive method was associated with increased risk of rectal cancer (HR(adj) = 1.68, 95% CI, 1.08-2.62) and reduced risk of thyroid cancer (HR(adj) = 0.63, 95% CI, 0.38-1.04). Risk of gallbladder cancer increased with ever use of OC (HR(adj) = 2.38, 95% CI, 1.26-4.49). IUD use was associated with a possible reduced risk of thyroid cancer (HR(adj) = 0.64, 95% CI, 0.38-1.07). Longer duration of IUD use decreased risk for breast, thyroid and lung cancers. Ever having a TS was associated with increased uterine body cancer (HR(adj) = 2.50, 95% CI, 1.47-4.25) and decreased risk of stomach cancer (HR(adj) = 0.59, 95% CI, 0.39-0.91). We did not find any contraceptive method to be related to the risk of ovarian cancer but the analyses were based on few events. Although chance findings are a likely explanation for some of the associations found in our study, these findings suggest that various contraceptive methods or reproductive patterns may play a role in the etiology of cancer.
Dorjgochoo
Tsogzolmaa
T
Vanderbilt Epidemiology Center, Department of Medicine, School of Medicine, Vanderbilt University, Nashville, TN 37203-1738, USA.
Shu
Xiao-Ou
XO
Li
Hong-Lan
HL
Qian
Han-Zhu
HZ
Yang
Gong
G
Cai
Hui
H
Gao
Yu-Tang
YT
Zheng
Wei
W
D000328:Adult; D000368:Aged; D003276:Contraceptives, Oral / Q000009:adverse effects*; D005260:Female; D006801:Humans; D007434:Intrauterine Devices / Q000009:adverse effects*; D008875:Middle Aged; D009369:Neoplasms / Q000145:classification / Q000209:etiology*; D011446:Prospective Studies; D012307:Risk Factors; D013246:Sterilization, Tubal / Q000009:adverse effects*
D003276:Contraceptives, Oral