The Impact of Radiation Dose to Bowel on the Risk of Developing Gastrointestinal Toxicities When Treating Abdominopelvic Soft-Tissue Sarcomas With Preoperative Radiation Therapy

Sep 29, 2026

Purpose: Abdominopelvic soft-tissue sarcomas are treated with preoperative radiation therapy followed by surgery. This study evaluates dosimetric predictors of acute and long-term gastrointestinal toxicities in patients receiving preoperative RT for abdominal and pelvic soft-tissue sarcomas. Methods: A retrospective 2005–2020 cohort used deep learning (nnU-Net) for auto-contouring bowel loops and a “Bowel Bag,” followed by review. Statistical tests related bowel dose to GI toxicity, while recurrence was analyzed with Kaplan-Meier methods. Results: Among 76 patients (median follow-up 46 months), about half had retroperitoneal tumors; acute grade 1–2 diarrhea occurred in 30% and grade 1 nausea in 18%. No acute grade 3 toxicities were seen. Long-term toxicity occurred in 8%. Exceeding Bowel Bag V45>195 cm3 increased acute GI toxicity risk (P=.05).

LanguageEnglish

CategoryHealthcare

FormatPDF

Pages8

Reading Time20 min

AccessFree to download

Purpose

Methods and Materials

Results

Conclusions

Introduction

Treatment background and rationale

Advances in Radiation Oncology (2026) 11, 101953 Scientiﬁc Article The Impact of Radiation Dose to Bowel on the Risk of Developing Gastrointestinal Toxicities When Treating Abdominopelvic Soft-Tissue Sarcomas With Preoperative Radiation Therapy Alison Yoder, MD,a,* Tucker Netherton, PhD,b Xin Wang, PhD,b Tze Lim, PhD,b Catherine Wang, PhD,b Dershan Luo, PhD,b Congjun Wang, PhD,b Sara Thrower, PhD,b Callistus Nguyen, PhD,b Heather Lyu, MD,c Christopher Scally, MD,c Christina Roland, MD,c Devarati Mitra, MD PhD,a Andrew Bishop, MD,a Ahsan Farooqi, MD PhD,a and B Ashleigh Guadagnolo, MDa aDepartment of Radiation Oncology, MD Anderson Cancer Center, Houston, Texas; bDepartment of Physics, MD Anderson Cancer Center, Houston, Texas; and cDepartment of Surgical Oncology, MD Anderson Cancer Center, Houston, Texas Received 28 May 2025; accepted 3 November 2025 Purpose: Abdominopelvic soft-tissue sarcomas (AP-STS) are selectively treated with radiation therapy (RT) followed by surgery. We investigated dosimetric factors predictive of acute and long-term gastrointestinal (GI) toxicities in patients treated with preoperative RT for AP-STS. Methods and Materials: We performed a retrospective cohort study of patients treated for nonmetastatic AP-STS with preoperative RT and surgery from 2005 to 2020. Individual loops of small and large bowel, as well as a “Bowel Bag” space, were autocontoured using a clinically validated deep learning-based approach (nnU-Net) and then manually reviewed. Chi-square or Fisher’s exact test was used to assess how bowel dosimetry related to the development of GI toxicities. In particular, the effect on GI toxicity of exceeding bowel constraints as deﬁned in the consensus guidelines was evaluated. Recurrence outcomes were analyzed using the Kaplan-Meier method. Results: We evaluated 76 patients with a median follow-up of 46 months (IQR, 42-50) . Approximately half of the tumors were located in the retroperitoneal space (n = 39, 51%) . A total of 60 patients (79%) presented with de novo disease, and 21%(n = 16) were recurrent presentations that had not received prior RT. Fourteen patients (18%) had a local recurrence alone, 23 (30%) a distant recurrence alone, and 3 (4%) combined local and distant recurrence. As a result of RT, 23 patients (30%) had acute grade 1 to 2 diarrhea, and 14 (18%) had grade 1 nausea. There were no acute grade 3 toxicities. Six patients (8%) had any long-term RT-related toxicity, including 1 small bowel obstruction. Patients were more likely to have an acute GI toxicity if bowel bag V45> 195 cm3 (P = .05) . Conclusions: Traditional RT volumetric bowel dose constraints are frequently exceeded, given the large size of AP-STS at presentation and the corresponding large RT volumes. Exceeding the conventional bowel dosimetric constraints should not dissuade the use of RT, but instead signal the need for aggressive prophylactic management of potential toxicities. © 2025 The Authors. Published by Elsevier Inc. on behalf of American Society for Radiation Oncology. This is an open access article under the CC BY-NC-ND license ([http://creativecommons.org/licenses/by-nc-nd/4.0/](http://creativecommons.org/licenses/by-nc-nd/4.0/)). Sources of support: Supported in part by Cancer Center Support (Core) Grant P30 CA016672 from the National Cancer Institute, National Institutes of Health, to The University of Texas MD Anderson Cancer Center. Research data are stored in an institutional repository and will be shared on request to the corresponding author. *Corresponding author: Alison Yoder, MD; Email: [ayoder@mdanderson.org](ayoder@mdanderson.org) [https://doi.org/10.1016/j.adro.2025.101953](https://doi.org/10.1016/j.adro.2025.101953) 2452-1094/© 2025 The Authors. Published by Elsevier Inc. on behalf of American Society for Radiation Oncology. This is an open access article under the CC BY-NC-ND license ([http://creativecommons.org/licenses/by-nc-nd/4.0/](http://creativeco

FAQs

What was the study’s main purpose?

To identify dosimetric factors that predict acute and long-term gastrointestinal toxicities in patients with abdominopelvic soft-tissue sarcomas treated with preoperative radiation therapy followed by surgery.

How were bowel and “Bowel Bag” structures assessed in the study?

Small and large bowel loops and a “Bowel Bag” space were autocontoured using a clinically validated deep learning approach (nnU-Net) and then manually reviewed.

Which dosimetric factor was associated with acute GI toxicity?

Patients were more likely to develop acute GI toxicity when bowel bag V45 was greater than 195 cm³ (P = .05).

What do the authors conclude about traditional bowel dose constraints?

Traditional volumetric bowel dose constraints were frequently exceeded; exceeding them should not discourage use of preoperative RT, but rather indicate the need for proactive prophylactic management of potential toxicities.

Sep 29, 2026

Uploaded by Rainbow Cat