Abstract
Little is known about the influence of prediagnosis and postdiagnosis smoking and smoking cessation on ovarian cancer survival. We investigated this relationship in two prospective cohort studies, the Nurses' Health Study (NHS) and NHSII. Analyses included 1,279 women with confirmed invasive, Stage I-III epithelial ovarian cancer. We used Cox proportional hazards regression models to estimate hazard ratios (HR) and 95% confidence intervals (CI) for ovarian cancer-specific mortality by smoking status, adjusting for age and year of diagnosis, tumor stage, histologic subtype, body mass index and nonsteroidal anti-inflammatory use (postdiagnosis models only). When examining prediagnosis smoking status (assessed a median of 12 months before diagnosis), risk of death was significantly increased for former smokers (HR = 1.19, 95% CI: 1.02-1.39), and suggestively for current smokers (HR = 1.21, 95% CI: 0.96-1.51) vs. never smokers. Longer smoking duration (≥20 years vs. never, HR = 1.23, 95% CI: 1.05-1.45) and higher pack-years (≥20 pack-years vs. never, HR = 1.28, 95% CI: 1.07-1.52) were also associated with worse outcome. With respect to postdiagnosis exposure, women who smoked ≥15 cigarettes per day after diagnosis (assessed a median of 11 months after diagnosis) had increased mortality compared to never smokers (HR = 2.34, 95% CI: 1.63-3.37). Those who continued smoking after diagnosis had 40% higher mortality (HR = 1.40, 95% CI: 1.05-1.87) compared to never smokers. Overall, our results suggest both prediagnosis and postdiagnosis smoking are associated with worse ovarian cancer outcomes.