"This is the first study in gynecological cancer to show the impact of advanced technology in reducing long-term morbidity and improving the survivorship experience of patients. Given these results, women undergoing postoperative radiation should receive image-guided IMRT," lead author Dr. Supriya Chopra, professor of radiation oncology at the Tata Memorial Centre in Mumbai, India, said in news release.
Dr. Chopra presented the results October 26 at the American Society for Radiation Oncology (ASTRO) virtual annual meeting.
"The uptake of IMRT has been relatively slow in gynecological cancers and there is a lack of clarity" on whether image-guided IMRT reduces late bowel toxicity, she explained at a press briefing.
To investigate, women undergoing adjuvant radiotherapy for cancer of the cervix were randomly allocated to IG-IMRT (142 women) or 3-D conformal radiation (3D-CRT, 141 women). The majority of women in both arms received concurrent chemotherapy and a brachytherapy boost following external radiation treatments.
"We observed a clear benefit of image-guided IMRT" on reducing late bowel toxicity, Dr. Chopra said in her presentation.
According to the conference abstract, at a median follow up of 48 months, 19.2% of patients in the IG-IMRT group experienced grade-2 or higher late bowel toxicity compared to 36.2% in the 3D-CRT group (hazard ratio, 0.53; P=0.005). Grade-3 or higher late bowel toxicity occurred in 2.0% of patients in the IG-IMRT group versus 8.7% of those in the 3D-CRT group (HR=0.23; P<0.01).
Overall, grade-2 or higher toxicity-free survival rates were significantly higher for patients treated with IG-IMRT (78% vs. 57% with 3D-CRT; HR, 0.47; P=0.0009), as were grade-3 or higher toxicity-free survival rates (97.6% vs. 81.6%, P=0.001).
With IG-IMRT, "there is a clear reduction in toxicity, with no difference in pelvic relapse," Dr. Chopra said in the news release. In a planned subgroup analysis, the benefit of iG-IMRT was more pronounced in patients receiving concurrent chemotherapy, she noted in her presentation.
Commenting on the study, briefing moderator Dr. Sue Yom of the University of California, San Francisco, said, "The use of higher-precision image-guided therapies in radiation oncology offers the possibility of improving radiation planning and improving cancer control and symptoms in patients. This study is one example of that which has potentially important impacts on future practice."
"This is the first phase-3 study that has shown definite long-term advantages with the use of IMRT and I would consider this practice changing," said Dr. Yom.
"One aspect that is very important and interesting about this study is that there was an interaction of the gastrointestinal outcome with the delivery of concurrent chemotherapy indicating that the patients who receive chemotherapy along with their radiation especially stand to benefit," she added.
The study had no commercial funding and the authors have no relevant disclosures.
By Megan Brooks
SOURCE: https://bit.ly/2HFaJzE ASTRO 2020 Annual Meeting, presented October 26, 2020.
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