Adding concurrent (chemo)therapy to radiotherapy improves outcomes for muscle-invasive bladder cancer patients. A recent meta-analysis showed superior invasive locoregional disease control for a hypofractionated 55 Gy in 20 fractions schedule compared with 64 Gy in 32 fractions. In the RAIDER clinical trial, patients undergoing 20 or 32 fractions of radical radiotherapy were randomised (1:1:2) to standard radiotherapy or to standard-dose or escalated-dose adaptive radiotherapy. Neoadjuvant chemotherapy and concomitant therapy were permitted. We report exploratory analyses of acute toxicity by concomitant therapy-fractionation schedule combination.
Participants had unifocal bladder urothelial carcinoma staged T2-T4a N0 M0. Acute toxicity was assessed (Common Terminology Criteria for Adverse Events) weekly during radiotherapy and at 10 weeks after the start of treatment. Within each fractionation cohort, non-randomised comparisons of the proportion of patients reporting treatment emergent grade 2 or worse genitourinary, gastrointestinal or other adverse events at any point in the acute period were carried out using Fisher's exact tests.
Between September 2015 and April 2020, 345 (163 receiving 20 fractions; 182 receiving 32 fractions) patients were recruited from 46 centres. The median age was 73 years; 49% received neoadjuvant chemotherapy; 71% received concomitant therapy, with 5-fluorouracil/mitomycin C most commonly used: 44/114 (39%) receiving 20 fractions; 94/130 (72%) receiving 32 fractions. The acute grade 2+ gastrointestinal toxicity rate was higher in those receiving concomitant therapy compared with radiotherapy alone in the 20-fraction cohort [54/111 (49%) versus 7/49 (14%), P < 0.001] but not in the 32-fraction cohort (P = 0.355). Grade 2+ gastrointestinal toxicity was highest for gemcitabine, with evidence of significant differences across therapies in the 32-fraction cohort (P = 0.006), with a similar pattern but no significant differences in the 20-fraction cohort (P = 0.099). There was no evidence of differences in grade 2+ genitourinary toxicity between concomitant therapies in either the 20- or 32-fraction cohorts.
Grade 2+ acute adverse events are common. The toxicity profile varied by type of concomitant therapy; the gastrointestinal toxicity rate seemed to be higher in patients receiving gemcitabine.
Clinical oncology (Royal College of Radiologists (Great Britain)). 2023 May 09 [Epub ahead of print]
R Huddart, S Hafeez, A Omar, R Alonzi, A Birtle, K C Cheung, A Choudhury, F Foroudi, H Gribble, A Henry, S Hilman, B Hindson, R Lewis, D Muthukumar, D B McLaren, H McNair, A Nikapota, A Olorunfemi, O Parikh, L Philipps, Y Rimmer, I Syndikus, A Tolentino, M Varughese, C Vassallo-Bonner, A Webster, C Griffin, E Hall
Division of Radiotherapy and Imaging, The Institute of Cancer Research, London, UK; Radiotherapy Department, The Royal Marsden NHS Foundation Trust, London, UK. Electronic address: ., Division of Radiotherapy and Imaging, The Institute of Cancer Research, London, UK; Radiotherapy Department, The Royal Marsden NHS Foundation Trust, London, UK., Clinical Trials and Statistics Unit at The Institute of Cancer Research, London, UK., Clinical Oncology, Mount Vernon Cancer Centre, East and North Hertfordshire NHS Trust, Middlesex, UK., Cancer Oncology, Lancashire Teaching Hospitals NHS Trust, Lancashire, UK., Translational Radiobiology, The Christie NHS Foundation Trust, Manchester, UK., Radiation Oncology, Austin Health, Heidelberg, Australia., University of Leeds and the Leeds Teaching Hospital NHS Trust, Leeds, UK., Clinical Oncology, University Hospitals Bristol and Weston NHS Foundation Trust, Bristol, UK., Canterbury Regional Cancer and Haematology Service, Te Whatu Ora, Waitaha Canterbury, Christchurch, New Zealand., Oncology, East Suffolk and North Essex NHS Foundation Trust, Colchester, UK., Department of Clinical Oncology, Edinburgh Cancer Centre, NHS Lothian, Edinburgh, UK., Clinical Oncology, Brighton and Sussex University Hospitals NHS Trust, Brighton, UK., Lancashire Teaching Hospitals NHS Trust, Burnley, UK., Department of Oncology, Cambridge University Hospitals NHS Foundation Trust, Cambridge, UK., Department of Radiotherapy, The Clatterbridge Cancer Centre, Liverpool, UK., Department of Oncology, Royal Devon & Exeter NHS Foundation Trust, Exeter, UK., Patient Representative, The Institute of Cancer Research, London, UK., National Radiotherapy Trials Quality Assurance Group (RTTQA), University College Hospital, London, UK.