EP248 - Short-Course Radiation in TNT: Implications for Non-Operative Management

Sunday, May 10, 2026

8:49 AM - 8:54 AM ET

ePoster Presenter(s)

Emily L. Bundy, MSc (she/her/hers)

Medical Student
WSU Elson S Floyd College of Medicine
Spokane, WA, United States

Disclosure information not submitted.

Author(s)

MA

Manar Al Rubaye, n/a

Medical Student
University of Wisconsin School of Medicine
Madison, Wisconsin, United States

Disclosure information not submitted.
Ana De Roo, MD (she/her/hers)

Assistant Professor
University of Wisconsin-Madison
University of Wisconsin-Madison
Madison, WI, United States

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

Senior Author(s)

DH

Dana M. Hayden, MD, MPH

Professor
University of Wisconsin-Madison
Mazomanie, Wisconsin, United States

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.

Ana De Roo, MD: This individual has no financial relationships with ineligible companies.

Dana M. Hayden, MD, MPH: This individual has no financial relationships with ineligible companies.

Purpose/Background: Purpose: As the standard of care has transitioned to total neoadjuvant therapy (TNT) for all locally advanced rectal cancer patients, the role of short course (SC) radiation may be controversial in the setting of the non-operative management algorithm.

Methods/Interventions:

Methods: A single-institutional retrospective review was performed for patients with stage II and III rectal cancer who underwent total neoadjuvant therapy (TNT) between 1/2014 and 12/2023.

Results/Outcomes:

Results: Of the 111 patients who underwent TNT, 17.1% underwent short-course (SC) radiation and 82.9% underwent long-course (LC). Among those who received SC, mean age was 58 years (35–80) and 36.8% were female. 31.5% had an ECOG performance status greater than 0 and had at least one comorbidity. Patients who had SC had a mean tumor distance from anal verge of 6.16 cm and a mean initial CEA level of 3.69. Age, sex, tumor height, sphincter involvement, and CEA levels were similar between the LC and SC groups, and notably there was no difference in T4 or N+ disease between groups. However, short course patients did have a slight but significantly higher BMI (30.9 vs. 29.7, p=0.044) and ECOG score (p=0.009) compared to those who had LC. Of those patients who underwent SC, 89.5% had induction chemotherapy. 21.1% had a restaging MRI performed after radiation was completed and only 1 SC patient had flexible endoscopy. 100% of SC patients went on to oncologic resection (68.4% low anterior resection, 21.1% abdominal perineal resection, 10.5% total proctocolectomy). No SC patients underwent non-operative management. Complete pathologic response (ypT0N0) was found in 15.8% of patients who underwent surgery.

Conclusion/Discussion:

Conclusions: Although short course radiation is an accepted option in the treatment of locally advanced rectal cancer, in our experience, SC is offered in conjunction with a planned surgical date and thus does not allow for consideration of non-operative management. Less than a quarter of SC patients had a restaging MRI performed and only one patient had a restaging endoscopy performed. Patients who underwent SC radiation were more likely to have worse performance status but otherwise had similar T stage and nodal disease and tumor height. The role of short course radiation may need to be reexamined in the setting of TNT and the discussion of non-operative management of rectal cancer.