EP907 - Trends in Pathological Response to Neoadjuvant Therapy for Rectal Cancer: Analysis of the National Cancer Database

ePoster Presenter(s)

• 

  Nir Horesh, MD

  Resident Physician
  Cleveland Clinic Florida
  Tel Aviv University
  Weston, FL, United States

  Disclosure information not submitted.

Author(s)

• 

  Sameh H. Emile, MBBCh, MSc, MD, FACS

  Project Scientist
  Cleveland Clinic Florida
  Cleveland Clinic Florida
  Weston, FL, United States

  Disclosure information not submitted.
• 

  Zoe Garoufalia, MD,PhD (she/her/hers)

  Colorectal Surgeon
  Hygeia Hospital
  Marousi, Attiki, Greece

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

  Michal Perets, MD

  Clinical Fellow
  Cleveland Clinic Florida
  The Hebrew University of Jerusalem, Israel
  Weston, FL, United States

  Disclosure information not submitted.
• MO

  Marcus Oosenbrug, MD CM (he/him/his)

  Clinical Associate
  Cleveland Clinic Florida
  Cleveland Clinic Florida
  Weston, Florida, United States

  Disclosure information not submitted.
• 

  Anjelli Wignakumar, MBBS, BSc (Hons) (she/her/hers)

  Clinical Research Fellow
  Cleveland Clinic Florida
  Cleveland Clinic Florida
  Weston, FL, United States

  Disclosure information not submitted.
• 

  Marylise Boutros, MD, FRCSC, FACS, FACRS (she/her/hers)

  Colorectal Surgeon
  Cleveland Clinic Florida
  McGill University
  Weston, Florida, United States

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

Senior Author(s)

• 

  Steven D. Wexner, MD, PhD (Hon)

  Surgeon
  Cleveland Clinic Florida
  Cleveland Clinic Lerner College of Medicine at Case Western Reserve University
  Weston, Florida, United States

  Disclosure information not submitted.

Purpose/Background: Management of locally advanced rectal cancer (LARC) has evolved with increasing adoption of neoadjuvant therapy (NAT). However, national trends in NAT utilization and associated pathologic responses remain underreported. This study aimed to evaluate real-world patterns of NAT use and corresponding responses in patients with LARC

Methods/Interventions: We conducted a retrospective cohort study using the National Cancer Database (2010-2021). Adults with clinical stage II-III rectal adenocarcinoma who underwent NAT followed by proctectomy were included. NAT was categorized as radiation alone, standard chemoradiotherapy, or total neoadjuvant therapy (TNT). Pathologic response was defined as complete, partial, or poor. Multivariable logistic regression was used to identify predictors of complete response.

Results/Outcomes: Among 36,573 patients, use of TNT increased from 27.5% in 2010 to 68.4% in 2021 (OR 6.84; 95% CI: 6.24-7.50; p< 0.001), surpassing standard chemoradiotherapy. Over time, TNT showed the greatest annual improvement in partial response (+1.09%/year; p< 0.001) and steepest decline in poor response (-1.67%/year; p< 0.001). Pathologic complete response (pCR) improved for both standard chemoradiotherapy (13.6% to 21.3%) and TNT (12.0% to 19.0%). Moderately differentiated tumors had the highest pCR (10.4%), while poorly differentiated and mucinous tumors were associated with poor responses (42.3% and 47.7%, respectively). Mucinous histology (OR 0.23; p< 0.001) and nodal disease (N1: OR 0.89; N2: OR 0.81; p< 0.001) were independently associated with lower odds of pCR.

Conclusion/Discussion: TNT has become the dominant neoadjuvant strategy for LARC, associated with improved response rates and increased adoption of sphincter-preserving approaches. However, tumor subtypes such as mucinous histology and poorly differentiated tumors remain less responsive, underscoring the need for tailored neoadjuvant approaches and intensified surveillance for high-risk patients.

Figure.
Trends in Pathological response to neoadjuvant therapy 2010-2021. (Left) Standard chemoradiation. (Right) Total Neoadjuvant Therapy