Patient-Reported Outcomes of Rectal Cancer Patients Treated on a 1.5T MR-Linac within the MOMENTUM Study.

Abstract

With the 1.5 MR-Linac, planning target volume (PTV) margins for the treatment of rectal cancer can be reduced by 1/3 compared to conventional radiotherapy techniques. This allows better sparing of surrounding tissues, potentially resulting in less toxicity and greater patient comfort. Patient-reported outcomes (PROs) after rectal cancer treatment on a 1.5T MR-Linac have not yet been reported. Through international collaboration, the 'Multi-OutcoMe EvaluatioN of radiation Therapy Using the MR-Linac (MOMENTUM)' registry provides the unique opportunity to study these outcomes in a relatively large patient cohort. The aim of this study is to assess PROs of rectal cancer patients treated on a 1.5T MR-Linac within MOMENTUM. An international, prospective, observational cohort study was performed, including all patients with rectal cancer who were treated with 25 Gy in five fractions on an MR-Linac in three institutions located in the Netherlands (2019-2022). Patient-reported outcomes were measured using the general EORTC QLQ-C30 and colorectal cancer-specific EORTC QLQ-CR29 questionnaires. Scores were calculated according to the EORTC QLQ-C30 scoring manual. A high score for a functional scale represents a high functioning level, while a high score for a symptom scale represents a high symptomatology level. Outcomes were measured at regular time points (i.e., at baseline and after three, 6 and 12 months follow-up). Patients who underwent tumor resection were censored at the date of surgery. In total, 152patients were included, with a median follow-up of 17 (interquartile range [IQR] 11-27) months. Of these, six patients (4%) had American Joint Committee on Cancer (AJCC) stage I disease, 11 patients (7%) stage II, 85 patients (56%) stage III, and 12 patients (8%) stage IV. A total of 87 patients (57%) reached three months follow-up without surgery, 60 patients (39%) six months, and 40 patients (26%) twelve months. At six months follow-up, 25/132 patients (19%) had received additional chemotherapy. The median global health score was 83 (interquartile range [IQR] 67-83) at baseline, 75 (IQR 58-83) at three months, 75 (IQR 58-83) at six months and 83 (IQR 83-100) at twelve months. In most QLQ-C30 domains, functional and symptom scores deteriorated during the first six months after treatment, but returned to or exceeded baseline scores at 12 months. Overall, treatment resulted in improved QLQ-CR29 scores after 12 months follow-up. Most frequently reported symptoms were blood and mucus in stool, urinary frequency, stool frequency and anxiety. This study presents patient-reported outcomes in the currently largest cohort of patients with rectal cancer who received treatment on a 1.5T MR-Linac. Overall, treatment resulted in improved symptom management, and stabilized or improved quality of life outcomes after twelve months of follow-up.