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Session:: ePosters-Sun800-M4: Colon & Colorectal Cancer

EP289 - What is The Value of Intraoperative Radiation Therapy In Rectal Cancer

Sunday, May 10, 2026
9:44 AM - 9:49 AM ET

    ePoster Presenter(s)

  • Rocco R. Ricciardi, MD

    Chief, Division of Colon & Rectal Surgery
    Massachusetts General Hospital
    Harvard University
    Boston, MA, United States

    Disclosure information not submitted.

    • Author(s)

  • HK

    Hiroko Kunitake, MD MPH

    Associate Professor
    Harvard Medical School, Massachusetts General Hospital
    Harvard Medical School, Massachusetts General Hospital
    Boston, MA, United States

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

  • SC

    Stalin Canizares Quisiguina, MD MPH

    Resident
    Massachusetts General Hospital
    Boston, Massachusetts, United States

    Disclosure information not submitted.

  • Grace C. Lee, MD

    Assistant Professor of Surgery
    Massachusetts General Hospital
    Harvard Medical School
    Boston, MA, United States

    Disclosure information not submitted.

  • Christy Cauley, MD, MPH (she/her/hers)

    Associate Professor
    Mass General Brigham
    Massachusetts General Brigham; Harvard Medical School
    Winchester, Massachusetts, United States

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

  • Robert N. Goldstone, MD

    Assistant Professor of Surgery
    Massachusetts General Hospital
    Harvard Medical School
    Boston, MA, United States

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

All of the relevant financial relationships listed below have been mitigated.
Hiroko Kunitake, MD MPH: This individual has no financial relationships with ineligible companies.
Christy Cauley, MD, MPH: This individual has no relevant relationships with ineligible companies.
Robert N. Goldstone, MD: This individual has no relevant relationships with ineligible companies.
Purpose/Background: Intraoperative radiation therapy (IORT) is part of the multimodal management of rectal cancer, normally reserved for select cases of locally advanced or recurrent rectal cancer with positive margins. There is controversy on whether IORT improves oncologic outcomes. In this study, we compared outcomes and overall survival between patients with rectal cancer undergoing adjuvant radiation therapy as compared to IORT.

Methods/Interventions: We analyzed data from the National Cancer Database (NCDB) of rectal cancer cases diagnosed between 1/2004 through 12/2022. Patients were stratified into two groups depending on the administration of IORT or adjuvant radiation without IORT. Both groups were propensity matched. Demographic and clinical baseline characteristics were compared using chi-square tests for categorical variables and t-tests for continuous variables. The primary endpoint was overall survival, evaluated using Kaplan-Meier survival curves and compared with the log-rank test. Multivariable Cox proportional hazards regression was performed to adjust for potential confounders and estimate hazard ratios with 95% confidence intervals.

Results/Outcomes: We classified patients into those who received postoperative radiation treatment (n = 590) and those who underwent IORT (n = 151). Among the latter, 70.9% received IOTR with other therapy before or after surgery. These patients were more likely to seek treatment at academic research programs (p <.001), had greater proportion of poorly differentiated or undifferentiated tumors (p=.005), had greater tumor size (p=.001) and had greater number of regional lymph nodes removed (p=.02) as compared to those who did not receive IORT. Groups were balanced in age, gender, race, insurance coverage, Charlson-Deyo score, pathologic stage group and surgical margins. The time between the initial diagnosis and the first course of treatment or the most definitive surgical resection was greater in the IORT group while the time up to the beginning of systemic therapy was shorter. 22% of patients receiving IORT had positive resection margins. After propensity marching, there was no difference in overall survival between those who received IORT as compared to those who received postoperative radiation.

Conclusion/Discussion: In the NCDB, patients treated with IORT presented with larger and more poorly differentiated tumors with treatment timelines suggested a more complex course of care. Despite these differences and after propensity matching overall survival did not significantly differ between groups.

Overall survival in patients who received intraoperative radiation versus those who received adjuvant radiation
Difference in overall survival for those who received intraoperative radiation (IORT)