Image-guided IMRT associated with fewer gastrointestinal adverse events in cervical cancer
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Image-guided intensity-modulated radiation therapy resulted in fewer gastrointestinal adverse events than 3D conformal radiation among women with cervical cancer, according to a phase 3 study presented at the virtual ASTRO Annual Meeting.
The results suggest image-guided IMRT could improve quality of life without compromising DFS rates, researchers noted.
“Postoperative radiation is indicated for women with cervical and endometrial cancers who have intermediate- or high-risk features. However, we know from long-term follow-up of especially endometrial cancer cohorts that there is an increase in gastrointestinal symptom burden and toxicity after adjuvant external radiation,” Supriya Chopra, MD, professor of radiation oncology at Tata Memorial Center in Mumbai, India, said during a press conference. “The uptake of IMRT has been relatively slow in gynecologic oncology. Until recently, there were only phase 2 studies that investigated a reduction in acute toxicity with IMRT, but there was no comparator arm in these trials. The phase 3 NRG 1203 trial did show an improvement in patient-reported outcomes at week 5 and year 1 with IMRT as compared with 3-dimensional conformal radiation, but at longer follow-up of 1 and 3 years, there was no benefit observed with IMRT. Therefore, there was a lack of clarity of the long-term impact of postoperative IMRT.”
Chopra and colleagues sought to assess whether image-guided IMRT could improve late gastrointestinal toxicity-free survival among women receiving adjuvant radiotherapy for cervical cancer across three clinical sites of Tata Memorial Center.
Researchers randomly assigned the women, all of whom had undergone hysterectomy, to either image guided IMRT (n = 142) or 3D conformal radiation (n = 141). Women also received a brachytherapy boost after external radiation, and 117 in the image-guided IMRT group and 114 in the 3D conformal radiation group received concurrent chemotherapy.
Grade 2 or higher toxicity-free survival served as the primary endpoint.
Median follow-up was 48 months (range, 2-108).
Results showed women assigned IMRT experienced fewer serious gastrointestinal adverse events (19% vs. 38%; HR = 0.53). Specifically, fewer women in the IMRT group reported moderate to severe acute diarrhea (17% vs. 27%), late abdominal bloating (14% vs. 28%), bowel obstruction (1% vs. 7%) and anorexia/appetite loss (1% vs. 7%).
Researchers found that women assigned IMRT had significantly higher rates of grade 2 (78% vs. 57%; P = .0009) and grade 3 (97.6% vs. 81.6%; P = .0001) toxicity-free survival, with no significant difference in DFS rates between the groups (73% vs. 68%).
Results of a subgroup analysis for grade 2 or higher toxicity-free survival showed a significant interaction between study intervention and treatment type (P = .01). A greater effect occurred among women who received adjuvant pelvic chemoradiation (HR = 0.4; 95% CI, 0.23-0.69) compared with women who received radiation therapy alone (HR = 0.78; 95% CI, 0.33-1.84).
No significant differences were observed between surgery types, researchers noted.
“Image-guided IMRT is superior to 3D conformal radiation in reducing late gastrointestinal toxicity in women undergoing postoperative pelvic radiation therapy,” Chopra said. “A greater benefit was observed with image-guided IMRT in those receiving radio-sensitizing concurrent chemotherapy, and there was no difference in tumor control rates in the pelvis with use of image-guided IMRT. Therefore, image-guided IMRT should represent the new standard of care for postoperative pelvic radiation therapy in women with gynecologic cancers.”
Perspective
Back to TopIMRT has had a slow integration into gynecological malignancies. This is due partly to the concerns of organ mobility and the previous success of the standard 3D-conformal pelvic field plan.
Previously published data from the TIME-C trial supported IMRT for women with cervical or endometrial cancer after hysterectomy. TIME-C demonstrated a statistically significant decrease in acute genitourinary and gastrointestinal toxicities with the use of an IMRT modality.
The PARCER trial further supports IMRT in the postoperative cervical cancer population with late-term toxicity results. At a median follow-up of 48 months, the PARCER trial demonstrates a significantly lower incidence of late grade 2 or higher toxicities with IMRT. Researchers observed no difference in DFS.
With supportive results in the acute- and late-term adverse effects, no difference in outcome and published contouring guidelines, IMRT should be the standard postoperative approach for women with cervical cancer, with or without concurrent chemotherapy.
Reference:
Klopp AH, et al. J Clin Oncol. 2018;doi:10.1200/JCO.2017.77.4273.
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Chopra S, et al. Abstract 2. Presented at: American Society for Radiation Oncology Annual Meeting (virtual); Oct. 25-28, 2020.
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