Circulating IGF system and treatment outcome in epithelial ovarian cancer

Aggressive epithelial ovarian cancers (EOCs) frequently progress and become fatal, even when cytoreduction surgery plus platinum-based chemotherapy are performed. Thus, the early detection of high-risk subgroups is important in order to provide opportunities for better treatment outcomes, using alternative therapeutic strategies. This study aimed to explore the expression of circulating IGF system components and their relationship with treatment outcome in EOC. We included 228 patients with a median follow-up time of 44 months at two tertiary centers. There were 68 cancer deaths and 108 cases of cancer progression in the cohort. Preoperative serum levels of total IGF1, IGF2, IGF-binding protein 2 (IGFBP2), and IGFBP3 were analyzed using an ELISA and were then converted into an IGF1:IGFBP3 molar ratio. The risks of mortality and progression were estimated using Cox regression models in univariate and multivariate analyses. Our results showed that high IGF1, IGF2, and IGFBP3 levels were significantly associated with an early cancer stage, non-serous histology, and optimal cytoreduction. High IGFBP2 levels were associated with an advanced stage and serous histology. Overall and progression-free survival durations were significantly better among patients with high IGF1 (P=0.003 and P=0.001), IGF2 (P=0.003 and P=0.02), or IGFBP3 levels (P=0.02 and P=0.008). In multivariate analysis, serum IGFBP2 levels were significantly associated with increased risk of mortality (hazard ratio=1.84, 95% CI: 1.07-3.18, P=0.03), indicating that IGFBP2 could be used as an early predictor of EOC-related mortality. The combination of elevated IGFBP2 and reduced IGF1 levels at diagnosis could further facilitate the identification of a patient subgroup with the worst prognosis.