Radiologic and surgical peritoneal cancer index in patients with low grade serous ovarian carcinoma

Peritoneal cancer index (PCI) is a numerical score that quantifies tumor extent in colorectal cancers. More recently it has been applied to ovarian cancers. However, the prognostic value of PCI in patients with low grade serous ovarian carcinoma (LGSOC) is not well characterized. We investigated whether pre-operative CT imaging could predict intraoperative disease extent and outcomes in LGSOC patients using PCI. We also investigated the association between PCI scores and cytoreduction outcomes.

Advanced stage LGSOC who had undergone preoperative CT imaging, cytoreductive surgery, and follow-up in the study timeframe were included. PCI was calculated based on the Sugarbaker method (Harmon & Sugarbaker, 2005). A blinded radiologist calculated CT-PCI scores. Surgical PCI was calculated retrospectively from operative reports. The relationship between CT-PCI and surgical PCI was determined using univariate linear regression. Surgical and survival outcomes were assessed.

For 21 patients (median age at cancer diagnosis = 58 years old, interquartile range (IQR) = 54-69), mean CT-PCI was 13 (SD: 8). Mean surgical PCI was 12 (SD: 7). CT-PCI significantly predicted surgical PCI (beta-coefficient = 0.59, p-value = 0.001). CT-PCI overestimated surgical PCI in 71 % of patients. Neither CT-PCI nor surgical PCI were significantly associated with optimal cytoreduction, though a trend was observed toward higher PCI scores in patients who were sub-optimally cytoreduced.

CT-PCI significantly predicts surgical PCI in a small, retrospective cohort of patients with LGSOC. CT-PCI may be useful to estimate surgical PCI and possibly cytoreductive outcome in LGSOC. However, CT-PCI can overestimate surgical PCI and should not be used to preclude LGSOC patients from a cytoreduction attempt.