Risk factors for second primary cancer in a prospective cohort of endometrial cancer survivors: an Alberta Endometrial Cancer Cohort Study

Abstract

We examined associations between modifiable and non-modifiable cancer-related risk factors measured at endometrial cancer diagnosis and during early survivorship (~3 years post-diagnosis) with second primary cancer (SPC) risk among 533 endometrial cancer survivors in the Alberta Endometrial Cancer Cohort using Fine and Gray sub-distribution hazard models. During a median follow-up of 16.7 years (interquartile range (IQR)=12.2-17.9), 89 (17%) participants developed a SPC with breast (29%), colorectal (13%) and lung (12%) cancers being the most common. Dietary glycemic load before endometrial cancer diagnosis (≥90.4 vs. <90.4 g/day: sub-hazard ratios (sHR)=1.71, 95% confidence intervals (CI)=1.09-2.69) as well as older age (≥60 vs. <60: sHR=2.48, 95% CI=1.34-4.62) and alcohol intake (≥2 drink/week vs. none: sHR=3.81, 95% CI=1.55-9.31) during early survivorship were associated with increased SPC risk. Additionally, reductions in alcohol consumption from prediagnosis to early survivorship significantly reduced SPC risk (sHR=0.34, 95% CI=0.14-0.82). With one-in-six survivors developing a SPC, further investigation of SPC risk factors and targeted surveillance options for high-risk survivors could improve long-term health outcomes in this population. Reductions in dietary glycemic load and alcohol intake from prediagnosis to early survivorship showed promising risk reductions for SPCs and could be important modifiable risk factors to target among endometrial cancer survivors.