Agricultural exposure and risk of ovarian cancer in the AGRIculture and CANcer (AGRICAN) cohort

Background: Ovarian cancer is rare with a poor prognosis and few established risk factors. Hormones and reproductive factors significantly impact its development, suggesting a potential link with endocrine disrupters.

Methods: In the AGRICAN cohort, 59 391 female farmers completed data on lifelong agricultural exposures and reproductive life. Cox models with attained age as timescale (HR and 95% CI) were used. The role of hormonal factors as potential confounders was considered along with specific time windows for exposure (childhood, puberty and menopause). Female farmers were the reference group (for the principal analyses).

Results: Between enrolment (2005-2007) and the end of follow-up (31 December 2017), 262 incident ovarian cancers were identified. An increased risk was observed for females involved in pigs (HR=2.12 (95% CI 1.27 to 3.52)) including during puberty (HR=1.83 (95% CI 1.13 to 2.94)), fruit-growing (HR=2.17 (95% CI 1.09 to 4.30)) and potato seed treatment (HR=2.81 (95% CI 1.29 to 6.09)). Conversely, females born on farms growing grain cereals (HR=0.64 (95% CI 0.46 to 0.90)) or pig-breeding (HR=0.78 (95% CI 0.55 to 1.12)) presented a reduced risk of ovarian cancer. Triazine herbicide exposure was not associated with ovarian cancer. The effect of agricultural exposures remained unchanged in multivariate models considering contraception, parity, puberty age, menopause age and body mass index.

Conclusion: This study is the first to assess the association between specific agricultural exposures and ovarian cancer comprehensively. Some of the positive associations observed suggest that some pesticide exposure (especially during puberty) could play a role in the development of ovarian cancer. On the other hand, agricultural exposure during early life could have a protective effect, as observed for lung cancer among farmers. Finally, we did not confirm the previous putative effect of exposure to triazine herbicides.