In the Canadian phase I/II SPARTACUS study reported in JAMA Oncology, Leung et al found very low rates of severe genitourinary and gastrointestinal toxicity and worsening in only one patient-reported outcome domain among women receiving adjuvant stereotactic hypofractionated pelvic radiation therapy for uterine cancers.
Study Background
As stated by the investigators, “Adjuvant radiation plays an important role in reducing locoregional recurrence in patients with uterine cancer. Although hypofractionated radiotherapy may benefit health-care systems and the global community while decreasing treatment burden for patients traveling for daily radiotherapy, it has not been studied prospectively nor in randomized trials for treatment of uterine cancers, and the associated toxic effects and patient quality of life are unknown.”
In the trial, 61 patients with stage I to III disease after surgery enrolled at two centers in Toronto between May 2019 and August 2021 received stereotactic adjuvant pelvic radiation to a dose of 30 Gy in five fractions given every other day or once weekly. Tumor histology included endometrioid adenocarcinoma in 39 patients, serous or clear cell disease in 15, carcinosarcoma in 3, and dedifferentiated disease in 4. Patient-reported outcomes were assessed with the European Organisation for Research and Treatment of Cancer (EORTC) QLQ-C30 and QLQ-EN24 modules.
Key Findings
Median follow-up was 9 months (interquartile range = 3–15 months). A total of 16 patients received sequential chemotherapy, and 9 received additional vault brachytherapy.
Among the 61 patients, worst acute gastrointestinal toxic effects of grade 1were observed in 33 patients (54%) and of grade 2 in 8 patients (13%). One patient (1.6%) had grade 3 diarrhea with the fifth radiotherapy fraction that resolved at follow-up. For worst genitourinary toxic effects, grade 1was observed in 25 patients (41%) and grade 2 in 2 patients (3%).
Among patient-reported outcomes, only diarrhea was significantly worse at fraction 5 vs baseline, both clinically (scores ≥ 10) and statistically (mean [standard deviation] score = 35.76 [26.34] vs 6.56 [13.36], P < .001). Patients reported improved symptoms during additional follow-up.
The investigators concluded: “Results of this phase I/II nonrandomized controlled trial suggest that stereotactic hypofractionated radiation was well tolerated at short-term follow-up for treatment of uterine cancer. Longer follow-up and future randomized studies are needed to further evaluate this treatment.”
Eric Leung, MD, MSc, of the Department of Radiation Oncology, Sunnybrook Health Sciences Centre, Odette Cancer Centre, Toronto, is the corresponding author for the JAMA Oncology article.
Disclosure: This study was funded by a Sunnybrook Health Sciences Centre Gynecological Oncology Foundation and Innovation grant, and London Health Sciences Centre, Academic Medical Organization of Southwestern Ontario. For full disclosures of the study authors, visit jamanetwork.com.
