A Phase III trial of 283 cervical cancer patients treated with postoperative radiotherapy found that higher radiation doses to the bowel (V30Gy and V40Gy) were linked to increased risk of acute and late diarrhea, as well as persistent gastrointestinal (GI) toxicity. The study, part of the PARCER trial, compared intensity-modulated radiotherapy (IMRT) with three-dimensional conformal radiotherapy (3DCRT).
Patients who received IMRT had a lower risk of late diarrhea and persistent GI toxicity compared to those who received 3DCRT. However, the models used to predict toxicity had modest accuracy, with area under the curve (AUC) values ranging from 0.588 to 0.761. This means the models are not yet precise enough for routine clinical use.
Additionally, patients who underwent radical hysterectomy with bilateral lymphadenectomy had a higher risk of persistent GI toxicity. The study followed patients for a median of 43 months, providing long-term data on side effects.
The findings suggest that limiting radiation doses to the bowel could help reduce GI side effects. However, the authors note that further research is needed to improve predictive models, standardize bowel contouring, and validate these results in other patient groups.