73: Predicting Early Recurrence to optimize Patient Selection for Cytoreductive Surgery-Hyperthermic Intraperitoneal Chemotherapy in High-Grade Appendiceal Mucinous Carcinoma Peritonei

Saturday, March 25, 2023

8:32 AM – 8:42 AM

Location: Ballroom B

Abstract Presenter(s)

Ahmed B. Hamed, MD

Post-doctoral associate
University of Pittsburgh
Allison Park, Pennsylvania, United States

Disclosure(s): No financial relationships to disclose

First Author(s)

Ahmed B. Hamed, MD

Post-doctoral associate
University of Pittsburgh
Allison Park, Pennsylvania, United States

Disclosure(s): No financial relationships to disclose

Author(s)

JD

Joshua Derby, BA

Data Coordinator and Analyst
University of Pittsburgh Medical Center, United States

Disclosure information not submitted.
MH

Matthew Holtzman, MD

Assistant Professor of Surgery
University of Pittsburgh Medical Center, United States

Disclosure information not submitted.
Melanie Ongchin, MD

Assistant Professor of Surgery
University of Pittsburgh Medical Center
Pittsburgh, Pennsylvania, United States

Disclosure information not submitted.
David L. Bartlett, MD

System Chair
Allegheny Health Network Cancer Institute
Pittsburgh, Pennsylvania, United States

Disclosure information not submitted.
JP

James F. Pingpank, Jr., MD

Associate Professor
University of Pittsburgh
Pittsburgh, PA, United States

Disclosure information not submitted.
RP

Reetesh Pai, MD

Professor of Pathology
University of Pittsburgh Medical Center, United States

Disclosure information not submitted.
AS

Aatur Singhi, MD, PhD

University of Pittsburgh Medical Center
Pittsburgh, Pennsylvania, United States

Disclosure information not submitted.
Mohammad Haroon A. Choudry, MD

Associate Professor of Surgery
University of Pittsburgh School of Medicine
Pittsburgh, Pennsylvania, United States

Disclosure information not submitted.

Disclosure(s):

Ahmed B. Hamed, MD: No financial relationships to disclose

Introduction: Cytoreductive surgery-hyperthermic intraperitoneal chemotherapy (CRS-HIPEC) for high-grade appendiceal mucinous carcinoma peritonei (HGaMCP) is sometimes associated with early recurrence (ER) and mortality. Predicting ER via factors known preoperatively/laparoscopically can improve patient selection.

Methods: A retrospective cohort study included all patients with HGaMCP (AJCC 8^th edition primary tumor G2/3) receiving initial CRS-HIPEC at a high-volume center between 2001-2020. We chose the ER threshold with the most significantly differing post-recurrence survival between ER and late recurrence/LR (i.e., resulting in the lowest p-value below α=0.05). Logistic regression (backward elimination) associated oncologic and perioperative factors with ER. Discrimination and calibration were verified. We created an ER risk score (ERRS) using the model’s beta-coefficients.

Results: A total 301 patients (median age 58 yrs, 47% female) received CRS-HIPEC for HGaMCP (G2: 205, G3: 96), and disease recurred in 170. At a 10-month ER threshold, 57 patients had ER. Median OS was worse for ER (16.4 months/mos) than LR (55 mos). In a multivariable logistic model, ASA >2 (odds ratio/OR 2.6, p=0.03), AJCC G3 (OR 1.8, p=0.07), cytoreduction completeness (CC) score >0 (OR 2, p=0.04), and PCI >20 (OR 1.7, p=0.1) were associated with ER. Discrimination (bootstrapped area-under-curve/AUC 0.704) and calibration were good. Assigned ERRS ranged 0-5. The 25 patients with ERRS of 5 had futile OS (median 10.7 mos), compared with scores 0-2 (96.5 mos), score 3 (41.8 mos), and score 4 (23.6 mos), with Kaplan-Meier survival curves in Fig 1. A Cox proportional hazards model adjusting for ERRS, ECOG, oncologic factors, and 90-day complications index (90CI) showed worse OS for ERRS of 5 (hazard ratio 3.6, p< 0.001) relative to low scores (0-2) with good discrimination (Harrell’s concordance index 0.74). Median 90CI was significantly worse for ERRS of 5 than scores 0-2 (52 vs 24). We obtained similar ER and OS models when including repeat CRS-HIPEC procedures.

Conclusions:

ER risk after CRS-HIPEC for HGaMCP is highest in ASA >2, CC-score >0, PCI >20, and AJCC G3. The poor associated morbidity/mortality warrants consideration of nonsurgical therapy in this subgroup with highest risk of ER.

Learning Objectives:

Identify the cutoff for early vs. late recurrence of high-grade appendiceal mucinous carcinoma peritonei (HGaMCP) after CRS-HIPEC
Understand the contribution of oncologic and perioperative factors to the risk of early recurrence after CRS-HIPEC
Apply an early recurrence risk score in decision-making to proceed with CRS-HIPEC for HGaMCP