ASPO Abstracts
Early life exposure to tobacco smoke and ovarian cancer risk in adulthood
Category: Lifestyles Behavior, Energy Balance & Chemoprevention
Conference Year: 2021
Abstract Body:
Background: Ovarian cancer risk in adulthood may be affected by early life exposure to
tobacco smoke. We investigated this relationship in two large prospective cohorts, the
Nurses' Health Study (NHS) and NHSII.
Methods: In total, analyses included 110,305 NHS participants (1976-2016) and 112,859
NHSII participants (1989-2017). Self-reported early life smoking exposures were queried
at baseline or follow-up questionnaires. Cox proportional hazards models were used to
estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for risk of ovarian
cancer overall and by tumor histotype.
Results: Compared with women who never smoked, ovarian cancer risk was similar for
women who started to smoke at age <18 (HR=0.98, 95%CI: 0.86-1.11) or ≥18 (HR=1.02,
95%CI: 0.93-1.12). Overall, ovarian cancer risk was not different among participants
whose mother did versus did not smoke during pregnancy (HR=1.05, 95%CI: 0.87-1.27);
however, an increased risk was observed among women who themselves were never
smokers (HR=1.38, 95%CI: 1.05-1.81) but not ever smokers (HR=0.86, 95%CI:
0.66-1.14; Pheterogeneity=0.02). These associations did not differ by histotype
(Pheterogeneity≥0.35). Parental smoking in the home during childhood/adolescence was
related to a 15% increased risk of ovarian cancer in adulthood (HR=1.15, 95%CI:
1.04-1.27) and this association was notably stronger among women with non-serous/ low-
grade serous tumors (HR=1.28, 95%CI: 1.02-1.61) versus high-grade serous/ poorly
differentiated tumors (HR=1.09, 95%CI: 0.93-1.28, Pheterogeneity=0.25).
Conclusions: Exposure to parental tobacco smoke, but not early initiation of smoking,
was associated with a modest elevated risk of ovarian cancer. Further investigations are
required to confirm these findings and elucidate underlying mechanisms.
Keywords: Ovarian neoplasm; smoking; early life; cohort studies