Objectives Currently, no clear guidance defining the ideal candidate for minimally invasive interval debulking surgery (MI-IDS) exists. This study aimed to identify predictive factors of minimally invasive approach feasibility in advanced ovarian cancer (AOC) patients who were candidates to IDS after neoadjuvant chemotherapy (NACT).

Methods This was a single institution, retrospective study. Perioperative variables were used to predict the likelihood of MI-IDS using multivariable models. A nomogram was developed, and internal validation was performed using the bootstrapping correction technique.

Results Between 2014 and 2020, 108 (28.4%) and 272 (71.6%) patients underwent IDS by minimally invasive and open approach, respectively. Surgeon’s expertise (OR:6.27, 95% CI:3.25–12.08, p≤0.001), absence of omental cake (OR: 8.56, 95% CI: 4.22–17.33, p≤0.001), <2 peritoneal sites involvement (OR:3.11, 95% CI:1.45–6.65, p=0.003) and complete serological response (OR:2.23, 95% CI:1.21–4.11, p=0.010) appeared to be significantly correlated with MI-IDS feasibility at multivariate analysis.

A nomogram was built to visualize the effect of perioperative variables on the estimated probability of MI-IDS in patients with a clinical response after NACT. We used the four significant perioperative variables according to logistic regression. The calibration plot demonstrated good agreement between the predicted and actual probability of MI-IDS (p=0.93, Hosmer-Lemeshow test).

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Abstract EPV218/#551 Figure 1

Co125_response indicates complete response (0) or partial/stable serologic response (1). Experience_in_MIS indicates good surgeon’s experience in MIS (1) or not (0). Pentoneal_involvement indicates ≥2 sites (1 of < 2 sites (0) involved. Omental_cake indicates presence (1) or absence (0) of oemental cake.To use, find Ca125 response om Ca125_response axes, then draw straight line upward to points axis to determine how many points patient receives for Ca125_response. Do this again for other axes, each time drawing straight line upward toward points axis. Sum points reveived for each variable and find sum on total points axis. Draw straight line down to probability of MIS-IDS axix to find find patient’s probability of receiving MIs-IDS.

Conclusions A nomogram might represent a useful tool to choose the best surgical approach in patients with AOC undergoing IDS.