BRIEF RESEARCH REPORT article
Front. Oncol.
Sec. Radiation Oncology
This article is part of the Research TopicInnovative Neoadjuvant Therapies and Surgical Techniques in Rectal Cancer Organ PreservationView all 3 articles
Post-radiation levator ani atrophy is associated with worse Low Anterior Resection Syndrome score after nonoperative management for locally advanced rectal cancer: a potential MRI biomarker
Provisionally accepted
- 1The University of Texas MD Anderson Cancer Center Division of Radiation Oncology, Houston, United States
- 2The University of Texas Health Science Center at Houston John P and Katherine G McGovern Medical School, Houston, United States
- 3The University of Texas MD Anderson Cancer Center Division of Diagnostic Imaging, Houston, United States
- 4The University of Texas MD Anderson Cancer Center Department of Rehabilitation Services, Houston, United States
- 5St Charles Health System, Bend, United States
- 6The University of Texas MD Anderson Cancer Center Department of Gastrointestinal Radiation Oncology, Houston, United States
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Background: Nonoperative management is increasingly offered to patients who achieve a complete clinical response to neoadjuvant therapy for rectal cancer. However, long-term bowel dysfunction and fecal incontinence can occur, potentially due in part to post-radiation fibrosis and atrophy of the pelvic floor muscles. In this pilot study, we investigated post-radiation changes in the levator ani muscles and their association with long-term patient-reported bowel dysfunction and incontinence scores. Methods: Fifteen patients with rectal cancer treated with definitive chemoradiation followed by nonoperative management were included. 2D and volumetric measurements of the levator ani were made on pre-treatment and 1-year post-radiation MRI. The changes in levator ani width and volume were correlated with the Low Anterior Resection Syndrome (LARS) and Fecal Incontinence Quality of Life (FiQOL) scores at least 1-year post treatment. Results: The 2D and volumetric measurements of the levator ani decreased between pre-treatment and 1-year post-radiation. (-21.0% and –21.7%, respectively; both P<0.01). The decrease in 2D levator ani measurements was positively associated with LARS score (Pearson r(13) = 0.55; P=.03) but not FiQOL score. The decrease in volumetric levator ani measurements was not significantly correlated with LARS or FiQOL scores. Conclusions: Decrease in 2D measurements of the levator ani from pre-treatment to 1-year post-radiation is correlated with higher LARS scores, indicating worse bowel function, perhaps due to radiation fibrosis and atrophy. This imaging biomarker may help to identify patients who could most benefit from pelvic floor physical therapy interventions. Further studies with larger cohorts are required to validate these findings.
Keywords: imaging biomarker, pelvic floor dysfunction, incontinence, radiation late effects, Fibrosis
Received: 30 Jun 2025; Accepted: 16 Dec 2025.
Copyright: © 2025 Thomas, Derasari, Palmquist, Samms, Andring and Holliday. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Emma B. Holliday
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