Radiotherapy treatment volume and associated patient outcomes: a systematic review and meta-analysis
Jerry Ye Aung Kyaw,
United Kingdom
OC-0757
Abstract
Radiotherapy treatment volume and associated patient outcomes: a systematic review and meta-analysis
Authors: Jerry Ye Aung Kyaw1, Ajay Aggarwal2, Alice Rendall2, Erin Gillespie3, Alison Tree4, Yolande Lievens5, Tom Roques6, Chris Frampton7
1Oxford University Hospitals NHS Foundation Trust HOSPITALS NHS FOUNDATION TRUST, Medicine, Oxford, United Kingdom; 2Guy’s and St Thomas’ NHS Foundation Trust, London, Clinical Oncology, London, United Kingdom; 3Memorial Sloan Kettering Cancer Center, Clinical Oncology, New York, USA; 4The Royal Marsden NHS Foundation Trust and the Institute of Cancer Research, Clinical Oncology, London, United Kingdom; 5Department of Radiation Oncology, Ghent University Hospital and Ghent University, Clinical Oncology, Ghent, Belgium; 6Norfolk and Norwich University Hospitals, Clinical Oncology, Norfolk and Norwich, United Kingdom; 7University of Otago, Medicine, Christ Church, New Zealand
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Purpose or Objective
Evidence of a volume-outcome association in cancer surgery has shaped the centralisation of cancer services, however it is unknown whether a similar association exists for radiotherapy. The aim of this study was to determine the association between radiotherapy treatment volume and patient outcomes.
Material and Methods
MEDLINE, EMBASE and citation searches of selected articles between January 1995 to January 2022 were undertaken. Selected studies included 1) patients who underwent curative radiotherapy; 2) hospital volume reported as a predictor variable; and 3) at least two hospital facilities.
PRISMA guidelines were used for abstracting data. Independent extraction was undertaken by two reviewers. For the meta-analysis, a random effects model was used. The Newcastle-Ottawa Scale was used for appraising study quality.
Absolute effects and hazard ratios (HRs) were used to compare outcomes such as overall survival, death, recurrence, or treatment related complication. For the studies that categorised volume into tertiles and quartiles, the meta-analysis used the hazard ratio of the lowest-volume group (reference) and the next lowest group to determine the most conservative pooled radiotherapy treatment volume and outcome relationship.
Results
The search identified 4356 papers. The association between radiotherapy volume and patient outcomes was assessed in 21 studies. The majority looked at head and neck cancers (HNCs) (n=7/21). The remaining studies covered cervical (n=4/21), prostate (n=4/21), bladder (n=3/21), lung (n=2/21), anal (n=2/21), oesophageal (n=2/21), brain (n=2/21), liver (n=1/21), and pancreatic cancer (n=1/21). The meta-analysis demonstrated that high-volume radiotherapy facilities (HVRFs) were associated with a lower chance of death compared to low-volume radiotherapy facilities (pooled HR 0.91; 95%CI 0.87-0.95) (See Figure 2). HNCs had the strongest evidence of a volume-outcome association for both nasopharyngeal cancer (pooled HR 0.74; 95%CI 0.62-0.89) and non-nasopharyngeal HNC subsites (pooled HR 0.80; 95%CI 0.75-0.84) followed by prostate (pooled HR 0.92; 95%CI 0.86-0.98) cancer. The remaining cancer types showed weak evidence of an association. The results also demonstrate that some centres defined as HVRFs were undertaking very few procedures per annum (< 5 radiotherapy cases/year).
Figure 1: PRISMA Diagram
Figure 2: Forest plot. Pooled HRs for overall survival comparing high to low-volume radiotherapy facilities for twelve cancer types; 18 studies were included in the meta-analysis; Tchelebi et al represents one study
Conclusion
An association between radiotherapy treatment volume and patient outcomes exists for most cancer types. Centralisation of radiotherapy services should be considered for cancer types with the strongest volume outcome association such as HNCs but the impact on equitable access to services needs to be explicitly considered. Very low volume practices should be consolidated or partnered with established HVRFs to support quality improvement.