ESTRO 2023 - Abstract Book

S306

Sunday 14 May 2023

ESTRO 2023

Fig 2. Assessment of risk of bias and applicability concerns

No external validation was performed for 244 models (73%). For the remaining 89 models and 4 additional models which were originally developed for patients with different types of cancer, 126 external validations were performed in 22 articles; most often for models that predicted outcomes related to saliva dysfunction (n=51, 40%), followed by swallowing (n=30, 24%) and hypothyroidism (n=24, 19%). The reported c-statistics after external validation ranged between 0.19 and 0.96. The overall ROB and applicability concerns were high in 67% and 10% of the external validations, respectively (Figure 2). Six models (3 for dysphagia and 3 for hypothyroidism) were identified with ≥ 2 external validations for the same outcome as in the original development study. Those models generally showed good discriminative performance. However, information on their calibration performance was largely lacking and ROB was high. As no model was externally validated at least 5 times, we could not perform any meta-analyses of the performance of models across validation studies. Conclusion Among 333 developed models, a limited number of studies had sufficient quality. Only one-fourth of them was externally validated, of which only 6 models at least twice. Most validation studies were judged as high ROB. This review shows the need for more external validation studies of developed models in clinical practice and improvement of the quality of conducting and reporting of prediction model studies in this subject. PD-0404 A multicentre UK review of toxicity after radical (chemo)radiotherapy for nasopharyngeal cancer R. Rieu 1 , R. Prestwich 2 , A. Swan 3 , D. Noble 3 , D. Srinivasan 4 , K. Chiu 5 , A. Scott 5 , L. Dixon 6 , R. Mendes 7 , A. Thompson 8 , A. Pilar 7 , R. Li 7 , S. Khan 7 , C. Nutting 9 , A. McPartlin 10 1 The Royal Marsden Hospital, Head and Neck Clinical Oncology, London, United Kingdom; 2 Leeds Cancer Centre, Department of Clinical Oncology, Leeds, United Kingdom; 3 Edinburgh Cancer Centre, Department of Clinical Oncology, Edinburgh, United Kingdom; 4 Edinburgh, Department of Clinical Oncology, Edinburgh, United Kingdom; 5 Mount Vernon Cancer Centre, Department of Clinical Oncology, Northwood, United Kingdom; 6 Weston Park Hospital, Department of Clinical Oncology, Sheffield, United Kingdom; 7 University College London Hospital, Department of Clinical Oncology, London, United Kingdom; 8 North Middlesex University Hospital NHS Trust, Department of Clinical Oncology, London, United Kingdom; 9 The Royal Marsden and the Institute of Cancer Research, Department of Clinical Oncology and Professor of Radiotherapy, London, United Kingdom; 10 Princess Margaret Cancer Centre, Department of Clinical Oncology, Toronto, Canada Purpose or Objective Nasopharyngeal cancers (NPC), rare outside endemic regions, are associated with excellent survival outcomes in the curative-intent setting. Despite introducing intensity modulated radiotherapy (IMRT), toxicity remains of concern. Contemporary data detailing toxicity, including patient reported outcomes (PROs), following radical treatment for NPC is limited; we present the largest UK multicentre study of toxicity outcomes and late PROs following NPC reported to date. Materials and Methods Adult patients completing radical (chemo)radiotherapy for NPC between February 2016 and February 2020 at seven large UK cancer centres were identified on institutional databases. Patients were excluded if they had prior head and neck cancer, prior therapeutic head and neck surgery (other than neck dissection), current other active cancer(s), or were treated for a non-primary-NPC. Demographic, treatment, acute toxicity and outcome data were collected retrospectively from patient records. Alive, disease-free patients completed patient reported outcome (PROs) questionnaires, including an M.D. Anderson Dysphagia Index (MDADI) and University of Washington (UoW) Quality of Life (QoL). Results A total of 180 patients fulfilled eligibility criteria; 68% were male, median age 54 years, 11% of patients were aged ≥ 70 years. EBV status was positive in 61% (unavailable in 12%). Patients had stage I (5%), II (22%), III (37%), and IV (36%) disease. 95% had a performance status between 0-1. 98% patients received either 70Gy in 33-35# or 65-66Gy in 33-35#. 66% received induction (chemo)radiotherapy (median 2, range 0-6 cycles), and 66% received concurrent chemotherapy (median 2 cycles, range 0-4). At completion of treatment 9.5% had residual disease. At a median follow-up of 32.1 months (range 0-68), 6.1% of patients required persistent tube feeding, 79% patients were alive and 16% had died (of which 70% had known active disease). Locoregional and distant recurrence was noted in 5% and 12% respectively. Patients lost an average of 7.1kg during therapy; 63% required enteral support. In those whose feeding tube was removed the median duration of use was 83 days. 18% experienced CTCAE grade 3 dermatitis, and 53% grade 3 mucositis. 82% received opioids and 40% were admitted during treatment. 90 patients completed the PROs (76% response rate) at a median of 37.8 months post treatment. Table 1 summarises the PRO results, demonstrating significant and persistent QoL issues. MDADI identified significant toxicity across all domains including 28% significant pain (24% require regular analgesia), and 59% significantly affecting daily activity.