Predicting Grade 3 Acute Diarrhea During Radiation Therapy for Rectal Cancer Using a Cutoff-Dose Logistic Regression Normal Tissue Complication Probability Model

Journal Article · Sat May 01 00:00:00 EDT 2010 · International Journal of Radiation Oncology, Biology and Physics

DOI:https://doi.org/10.1016/j.ijrobp.2009.04.048· OSTI ID:21372241

Soehn, Matthias ^[1]; Di, Yan ^[2]

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1. University of Tuebingen, Tuebingen (Germany)
2. William Beaumont Hospital, Royal Oak, Michigan (United States)

Purpose: Understanding the dose-volume relationship of small bowel irradiation and severe acute diarrhea may help reduce the incidence of this side effect during adjuvant treatment for rectal cancer. Methods and Materials: Consecutive patients treated curatively for rectal cancer were reviewed, and the maximum grade of acute diarrhea was determined. The small bowel was outlined on the treatment planning CT scan, and a dose-volume histogram was calculated for the initial pelvic treatment (45 Gy). Logistic regression models were fitted for varying cutoff-dose levels from 5 to 45 Gy in 5-Gy increments. The model with the highest LogLikelihood was used to develop a cutoff-dose normal tissue complication probability (NTCP) model. Results: There were a total of 152 patients (48% preoperative, 47% postoperative, 5% other), predominantly treated prone (95%) with a three-field technique (94%) and a protracted venous infusion of 5-fluorouracil (78%). Acute Grade 3 diarrhea occurred in 21%. The largest LogLikelihood was found for the cutoff-dose logistic regression model with 15 Gy as the cutoff-dose, although the models for 20 Gy and 25 Gy had similar significance. According to this model, highly significant correlations (p <0.001) between small bowel volumes receiving at least 15 Gy and toxicity exist in the considered patient population. Similar findings applied to both the preoperatively (p = 0.001) and postoperatively irradiated groups (p = 0.001). Conclusion: The incidence of Grade 3 diarrhea was significantly correlated with the volume of small bowel receiving at least 15 Gy using a cutoff-dose NTCP model.

• OSTI ID: 21372241
• Journal Information: International Journal of Radiation Oncology, Biology and Physics, Vol. 77, Issue 1; Other Information: DOI: 10.1016/j.ijrobp.2009.04.048; PII: S0360-3016(09)00646-4; Copyright (c) 2010 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; ISSN 0360-3016
• Country of Publication: United States
• Language: English

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62 RADIOLOGY AND NUCLEAR MEDICINE
CAT SCANNING
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FLUOROURACILS
INFUSION
NEOPLASMS
PLANNING
RADIOTHERAPY
RECTUM
SIDE EFFECTS
THREE-DIMENSIONAL CALCULATIONS
TOXICITY
ANTIMETABOLITES
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DISEASES
DRUGS
GASTROINTESTINAL TRACT
HETEROCYCLIC COMPOUNDS
HYDROXY COMPOUNDS
INTAKE
INTESTINES
LARGE INTESTINE
MEDICINE
NUCLEAR MEDICINE
ORGANIC COMPOUNDS
ORGANIC FLUORINE COMPOUNDS
ORGANIC HALOGEN COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANS
PYRIMIDINES
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SYMPTOMS
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URACILS