Rectal Dose Is the Other Dosimetric Factor in Addition to Small Bowel for Prediction of Acute Diarrhea during Postoperative Whole-Pelvic Intensity-Modulated Radiotherapy in Gynecologic Patients.

Eng-Yen Huang,Shu-Yu Liu,Yu-Ming Wang,Ming-Chung Chou,Shih-Chen Chang

doi:10.3390/cancers13030497

Eng-Yen Huang, Shu-Yu Liu + Show 3 more

Open Access

https://doi.org/10.3390/cancers13030497

Copy DOI

Abstract

Simple SummaryAlthough the small bowel volume effect for acute diarrhea during radiotherapy has been investigated, no study has reported the influence of rectal dose. We analyzed 108 patients undergoing intensity-modulated radiotherapy after hysterectomy. Acute diarrhea was defined as onset during radiotherapy based on Common Terminology Criteria for Adverse Events (CTCAE) version 3. Both small bowel and rectum dosimetric parameters affected Grade 2 to 3 diarrhea. The high-dose volume effects on the small bowel still play an important role in postoperative intensity-modulated radiotherapy. This is the first large cohort study to demonstrate the role of both IMRT dosimetric factors of the rectum and the small bowel in acute diarrhea in gynecological patients with a previous hysterectomy. A small bowel volume of 39.6 Gy < 60 mL and a mean rectal dose of <32.75 Gy are suggested as constraints to treatment planning.We studied the association of rectal dose with acute diarrhea in patients with gynecologic malignancies undergoing whole-pelvic (WP) intensity-modulated radiotherapy (IMRT). From June 2006 to April 2019, 108 patients with previous hysterectomy who underwent WP IMRT were enrolled in this cohort study. WP irradiation of 39.6–45 Gy/22–25 fractions was initially delivered to the patients. Common Terminology Criteria for Adverse Events (CTCAE) version 3 was used to evaluate acute diarrhea during radiotherapy. Small bowel volume at different levels of isodose curves (Vn%) and mean rectal dose (MRD) were measured for statistical analysis. The multivariate analysis showed that the MRD ≥ 32.75 Gy (p = 0.005) and small bowel volume of 100% prescribed (V100%) ≥ 60 mL (p = 0.008) were independent factors of Grade 2 or higher diarrhea. The cumulative incidence of Grade 2 or higher diarrhea at 39.6 Gy were 70.5%, 42.2%, and 15.0% (p < 0.001) in patients with both high (V100% ≥ 60 mL and MRD ≥ 32.75 Gy), either high, and both low volume-dose factors, respectively. Strict constraints for the rectum/small bowel or image-guided radiotherapy to reduce these doses are suggested.

Highlights

Acute gastrointestinal (GI) toxicities are common side effects during pelvic radiotherapy
V10% was defined as the small bowel volume covered at 10% of the isodose curve, and V20% to V100% were recorded for analysis
We evaluated patients weekly and recorded the onset time of any grade of diarrhea in the chart during radiotherapy

Summary

Introduction

Acute gastrointestinal (GI) toxicities are common side effects during pelvic radiotherapy. They are usually transient and reversible, consequential late effects may be troublesome to management in some studies. It is important to reduce the incidence and severity of GI toxicities as much as possible to improve patient quality of life. Symptoms of toxicity are nausea, vomiting, diarrhea, tenesmus, and abdominal cramping. Diarrhea is the most common symptom used for evaluating toxicity and is caused by radiation damage to the bowels, which leads to impairment of water absorption. Radiation-induced inflammation may cause hypermobility and further impairment of bowel function. The small bowel, colon, and rectum are commonly defined as organs at risk (OARs) in radiotherapy, and the excessive irradiation of these OARs could result in GI complications

Objectives

Methods

Discussion

Conclusion