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Session: ePoster: Colon and Colorectal Cancer 19 (Tue8)

EP933 - Diagnostic Models for Improving positive predictive value of mrTRG1-2 in the Prediction of Good Responders after Chemoradiotherapy in Rectal Cancer

Tuesday, May 13, 2025
8:10 AM – 8:15 AM PT

    ePoster Presenter(s)

  • Kyongmin Kang, General surgeon

    Seoul National University Bundang Hospital
    Department of Surgery
    Seoul, Seoul-t'ukpyolsi, Republic of Korea

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

    • Author(s)

  • Mi Jeong Choi

    Fellow
    Seoul national university Bundang hospital
    Seongnam-si, Kyonggi-do, Republic of Korea

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

  • Min-Hyeong Jo, MD

    Fellow
    Seoule national university Bundang hospital
    seongnamsi, Kyonggi-do, Republic of Korea

    Disclosure information not submitted.

  • HA

    Hong-Min Ahn, M.D.

    Professor
    Seoul National University Bundang Hospital
    Seoul, Seoul-t'ukpyolsi, Republic of Korea

    Disclosure information not submitted.

  • HO

    Heung-Kwon Oh, n/a

    Clinical Professor
    SNUBH
    Seoul, Seoul-t'ukpyolsi, Republic of Korea

    Disclosure information not submitted.

  • DK

    Duck-Woo Kim, n/a

    Professor
    Seoul National University Bundang Hospital
    Seoul, Kyonggi-do, Republic of Korea

    Disclosure information not submitted.

    • Senior Author(s)

  • SK

    Sung-Bum Kang, n/a

    Professor
    Seoul National University Bundang Hospital
    Seoul, Kyonggi-do, Republic of Korea

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

All of the relevant financial relationships listed below have been mitigated.
Kyongmin Kang, General surgeon: This individual has no financial relationships with ineligible companies.
Mi Jeong Choi: This individual has no financial relationships with ineligible companies.
Sung-Bum Kang, n/a: This individual has no financial relationships with ineligible companies.
Image or Table (Do Not add text here):

Purpose/Background: While MRI-based tumor regression grade has shown promise for evaluating the pathologic response to concurrent chemoradiotherapy (CCRT) in rectal cancer, its ability to predict pathologic complete response remains limited. This study aims to enhance the diagnostic performance of mrTRG in predicting ypT0-1N0 status, a key factor for considering non-radical management after CCRT in locally advanced rectal cancer.

Methods/Interventions: This retrospective study included 430 patients with locally advanced rectal cancer who underwent radical resection following CCRT at a single referral hospital between April 2018 and September 2024. Gross tumor type was assessed through digital rectal examination and endoscopy before CCRT. Multivariable logistic regression was used to identify the predictive factors associated with ypT0-1N0. Diagnostic performance of mrTRG1–2 alone and in combination with other factors was assessed by comparing sensitivity, specificity, positive predictive value, negative predictive value and area under the curve (AUC).

Results/Outcomes: Ninety-three patients (21.6%) achieved ypT0–1N0. In multivariable analysis, cT1-2 (57.4% vs 17.2% with cT3-4, P< 0.01), fungating type (65.9% vs 9.7% with infiltrating type, P< 0.01) and mrTRG1-2 (41.5% vs 13.9% with mrTRG3-5, P< 0.01) were significant independent predictors for ypT0-1N0. The combination of mrTRG with gross tumor type yielded the highest AUC (0.689, 95% CI: 0.620-0.759), compared to mrTRG (AUC: 0.678, 95% CI: 0.613-0.742). For predicting ypT0-1N0, the combination of mrTRG with gross type improved the positive predictive value (79.2% vs. 41.5% for mrTRG alone)

Conclusion/Discussion: This study is the first to demonstrate that combining mrTRG1-2 and gross fungating type significantly improves the positive predictive value of mrTRG alone in predicting ypT0-1N0 after CCRT in locally advanced rectal cancer. Therefore, we suggest that this combined diagnostic model could help identify candidates for non-radical management following CCRT.