Introduction/Background Macroscopically complete tumor debulking in primary surgery of advanced ovarian cancer is crucial for prognosis. Our study explores the link between Peritoneal Carcinoma Index (PCI) and the need for small bowel resection, the necessity of which we have found to be associated with compromised long-term outcome.

Methodology 15-year retrospective study (01/2006 - 12/2020) of primary maximum effort cytoreductive surgery in n = 326 patients with ovarian cancer FIGO IIIB, IIIC or IV. Peritoneal Carcinoma Index (PCI) and necessity of small bowel resection was assessed by reviewing surgical reports and intraoperative photo documentation. Relation to long-term outcome was analyzed.

Results PCI was documented in surgery reports of n = 119 patients and was retrospectively determined in n = 113 patients. Mean PCI in the region of small intestine and mesentery (PCI regions 9–12) was higher in patients with (6.33, 95% CI 5.44 – 7.22) vs. without (4.22, 95% CI 3.66 – 4.78) subsequent small bowel resections (p < 0.001, Mann-Whitney U test). Risk for small bowel resection increased with each additional point of PCI_9–12 (OR 1.168, 95% CI 1.073 - 1.270, p < 0.001). In ROC analysis, PCI_9–12 showed a reasonable predictive power (AUC 0.666, 95% CI 0.589 – 0.744). Risk for recurrence or death was significantly increased in patients with small bowel resection (HR 2.050, 95% CI 1.435 – 2.928, p < 0.001) and with each point of PCI_9–12 (HR 1.096, 95% CI 1.051 – 1.144, p < 0.001).

Conclusion PCI serves as a valuable tool for pre-debulking risk assessment of critical tumor spread to small bowel. PCI evaluation prior to primary cytoreductive surgery using less invasive tools including laparoscopy may identify patients who could benefit from alternative therapeutic approaches.

Disclosures None.