EP394 - Prognostic Factors and Survival Outcomes Following Salvage Abdominoperineal Resection for Stage I–III Anal Squamous Cell Carcinoma

ePoster Presenter(s)

• 

  Chidiebere Onongaya, MD, MS

  Resident
  University of Minnesota
  University of Minnesota
  Minneapolis, MN, United States

  Disclosure information not submitted.

Author(s)

• 

  Julia Frebault, MD (she/her/hers)

  General Surgery Research Resident
  University of Minnesota
  University of Minnesota
  Minneapolis, MN, United States

  Disclosure information not submitted.
• 

  Anmol Nigam, MD (he/him/his)

  General Surgery Resident
  University of Minnesota
  Univeristy of Minnesota
  Minneapolis, MN, United States

  Disclosure information not submitted.
• SM

  Sarah Mott, MS

  Biostatistician
  University of Iowa Holden Comprehensive Cancer Center
  Iowa City, Iowa, United States

  Disclosure information not submitted.
• SM

  Schelomo Marmor, PhD

  Associate Professor
  University of Minnesota
  Minneapolis, Minnesota, United States

  Disclosure information not submitted.
• IH

  Imran Hassan, MD

  Attending Surgeon
  Mercy Medical Center
  Cedar Rapids, Iowa, United States

  Disclosure information not submitted.

Senior Author(s)

• 

  Paolo Goffredo, MD (he/him/his)

  Assistant Professor
  University of Minnesota
  Minneapolis, MN, United States

  All of the relevant financial relationships listed below have been mitigated.
  This individual has no financial relationships with ineligible companies.

Author(s)

• JH

  James V. Harmon, Jr., MD, PhD

  Associate Professor
  University of Minnesota
  Minneapolis, Minnesota, United States

  Disclosure information not submitted.

Purpose/Background: Chemoradiation (CRT) can be curative in up to 90% of cases of non-metastatic squamous cell carcinoma (SCC). However, a subset of patients do not respond to treatment or experiences locoregional failure, and require salvage abdominoperineal resection (APR). This is associated with significant perioperative morbidity and has a reported 40-50% five year overall survival (OS). Prognostic factors impacting outcomes after surgery remain understudied. The aim of this study was to evaluate the OS of these patients following a salvage APR and prognostic factors associated with it.

Methods/Interventions: The National Cancer Database was queried for patients with clinical stage I-III anal SCC who received CRT and subsequently underwent APR between 2006 and 2021. Those who received immunotherapy were excluded. Logistic, Kaplan-Meir, and Cox regression models assessed the impact of demographic and clinical variables on positive surgical margins and overall survival (OS).

Results/Outcomes: A cohort of 370 patients was identified (43% male and 88% White). Over half (63%) had clinical stage III disease, and on pathology, 30% of tumors were T2, 26% T3, and 20% T4. Positive margins were seen in 19% of patients. Survival curves comparing patients with positive and negative margins are depicted in Figure 1. The overall five and ten year survival rate was 41% and 29% respectively. Ninety-day mortality was 7%. On multivariable analysis, males and residence in low-income areas were independently associated with increased odds of positive surgical margins (OR 1.89, 95% CI 1.04-3.45). The five and ten-year OS rates were 41% and 29% respectively.. After adjusting for available cofounders, male sex (HR 1.56, 95% CI 1.09-2.23), low-income residence (HR 1.60, 95% CI 1.11-2.30), pathologic T3/T4 disease (HR 2.47, 95% CI 1.72-3.56), and positive surgical margins (HR 2.34, 95% CI 1.52-3.59) were all independently associated with increased risk of mortality.

Conclusion/Discussion: In this nationwide cohort of patients with anal SCC who underwent CRT followed by salvage APR, positive surgical margins were observed in approximately 1 in 5 patients. Post-operative mortality was not significant. Male gender was independently associated with positive surgical margins, while advanced tumor stage and positive margins were independently associated with decreased OS, These findings highlight the importance of patient selection and surgical technique, given the substantial morbidity and challenges of achieving negative margins in these patients.

Figure 1. Kaplan-Meier survival curves for patients with positive and negative margins after salvage abdominoperineal resection.