75P Association between pre-diagnosis screen time and ovarian cancer survival: Findings from the ovarian cancer follow-up study — A prospective cohort study

Screening time (ST), a highly prevalent sedentary behaviour, may affect a variety of health outcomes. However, the relationship with ovarian cancer (OC) survival is relatively unknown. The objective of our study was to firstly clarify the association between ST and OC survival based on the Ovarian Cancer Follow-Up Study, a prospective cohort study in China. We assessed the association between ST and OC survival based on a prospective cohort study of 590 newly diagnosed OC patients aged 18-79 years. Deaths were ascertained until March 31, 2021, via medical records and active follow-up. Multivariable-adjusted Cox proportional hazards regression was used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) with pre-diagnosis ST and all-cause mortality of OC. The isotemporal substitution analysis was used to examine the risk of OC mortality associated with ST with alternative activities. Additionally, we explored the interaction between ST and demographic and clinical characteristics including immunohistochemical biomarkers. During a median follow-up of 42.00 (interquartile: 31.00-52.73 months), 130 deaths were identified. Patients who reported ≥5, compared with <2, hours/day of pre-diagnosis ST had higher risk of OC mortality (HR=2.58, 95%CI: 1.40-4.77, P trend<0.05). Similar adverse effect was found in phone and computer viewing (HR ≥3 vs. <1 hours/day =2.24, 95%CI: 1.30-3.84, P trend<0.05), whereas finding was non-significant for TV viewing time (HR ≥3 vs. <1 hours/day =1.61, 95%CI: 0.77-3.38, P trend=0.10). Additionally, isotemporal substitution models showed reduced risk of OC mortality when replacing 2-hour/day of ST with 2-hour of walking (HR=0.50, 95%CI: 0.26-0.97) or sleeping (HR=0.52, 95%CI: 0.38-0.71). Furthermore, we observed curvilinear association between ST and OC survival. Interestingly, there were significant interactions between ST and WT-1, estrogen receptor, and progesterone receptor expression (P<0.05). Our findings firstly indicated that high level of pre-diagnosis ST potentially contributed to increasing all-cause mortality among OC patients. Further studies are warranted to confirm our findings.