Treatment with image-guided intensity-modulated radiotherapy (IG-IMRT) led to reduced late toxicities vs standard three-dimensional (3D) conformal radiotherapy in patients with cervical cancer, according to data presented by Supriya Chopra, MD, and colleagues during the Society of Gynecologic Oncology (SGO) 2021 Virtual Annual Meeting on Women’s Cancer.¹
Supriya Chopra, MD
Final analysis of the PARCER study showed that grade ≥ 2 gastrointestinal toxicity–free survival improved to 78% with IG-IMRT at the end of 3 years vs 57% with 3D conformal radiation therapy, while grade ≥ 3 toxicity–free survival was 98% with IG-IMRT compared to 82% with 3D conformal radiation therapy.
“This is the first randomized trial that gives a clear signal of difference in reduction of late toxicity over a long period of follow-up,” said Dr. Chopra, of Tata Memorial Centre in Mumbai and Homi Bhabha Cancer Hospital in Sangrur, India. “If you look at the proportion of patients in the two arms who continue to report symptoms, there is a significant reduction in patients who were treated with IG-IMRT.”
She added, “We believe that the results of the trial are going to have an impact on a lot of women around the world.”
Postoperative radiation is indicated for cervical and endometrial cancers, but studies have shown an increase in gastrointestinal burden and toxicity in long-term survivors following adjuvant radiation. Although the phase II RTCMIENDOMETRE trial demonstrated a 27% to 28% acute gastrointestinal toxicity with IG-IMRT, said Dr. Chopra, it lacked a comparator arm, and there were no robust data on late toxicity.²
PARCER Trial
Conducted across three clinical sites of Tata Memorial Centre, the PARCER trial enrolled approximately 300 adult patients with cervical cancer. Individuals with type III hysterectomy with intermediate or high-risk features or type I/II hysterectomy necessitating adjuvant chemoradiation were included, while those with positive aortic nodes or indication for extended-field radiotherapy, a history of multiple previous abdominal surgeries and/or radiation, or any medical condition predisposing to bowel toxicity were excluded from the study.
According to Dr. Chopra, one of the keys to the study was the uniformity of how treatment was executed in both the intervention and control arms and the high-quality data acquired prospectively. Dr. Chopra and colleagues longitudinally captured 11 different treatment-related gastrointestinal toxicity items, along with quality-of-life parameters.
The study’s primary endpoint showed a “very clear difference in late grade 2 or higher gastrointestinal toxicity-free survival,” reported Dr. Chopra.
At the end of 3 years, 75% of patients receiving IG-IMRT were free of grade 2 gastrointestinal toxicities compared to only 58% of patients receiving 3D conformal radiation therapy, and grade 3 or higher toxicity-free survival was 98% vs 82%, respectively. In addition, data showed a significant reduction in acute diarrhea among patients assigned to receive IG-IMRT vs 3D conformal radiation therapy.
Investigators also observed greater benefit of IG-IMRT in those receiving concurrent chemotherapy, said Dr. Chopra, although study was underpowered to draw conclusions on this subgroup.
Image-guided intensity-modulated radiotherapy should represent the new standard of care for postoperative pelvic radiation therapy … and it’s our responsibility as a community to bring this high level of care to those who need it most.— Supriya Chopra, MD
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According to Dr. Chopra, the benefit of this study could even extend beyond patients with cervical cancer. However, she cautioned that implementing these results may pose a challenge in low middle–income countries.
“Results of this trial could also have an impact on women treated with endometrial cancer because it’s the same target volume, the same target field, and same treatment technique,” said Dr. Chopra. “However, up to 80% of women with cervical cancer may not have access to this advanced technology.”
“Image-guided intensity-modulated radiotherapy should represent the new standard of care for postoperative pelvic radiation therapy … and it’s our responsibility as a community to bring this high level of care to those who need it most,” she concluded.
Disclosure: Funding for the PARCER trial was provided by the Department of Science and Technology, India; Department of Atomic Energy, Clinical Trials Centre, in India; and Tata Memorial Centre. Varian International and Terry Fox International provided additional research funding.
References
1. Chopra S: Phase III randomized trial of postoperative adjuvant conventional radiation (3DCRT) versus image guided intensity modulated radiotherapy (IG-IMRT) in cervical cancer (PARCER): Final analysis. Society of Gynecologic Oncology Virtual Annual Meeting on Women’s Cancer. Abstract ID # 10224.
2. Barillot I, Tavernier E, Peignaux K, et al: Impact of post operative intensity modulated radiotherapy on acute gastro-intestinal toxicity for patients with endometrial cancer: Results of the phase II RTCMIENDOMETRE French multicentre trial. Radiother Oncol 1:138-143, 2014.
