Use of radiotherapy in patients with oesophageal, stomach, colon, rectal, liver, pancreatic, lung, and ovarian cancer: an International Cancer Benchmarking Partnership (ICBP) population-based study

Background There is little evidence on variation in radiotherapy use in different countries, although it is a key
treatment modality for some patients with cancer. Here we aimed to examine such variation.
Methods This population-based study used data from Norway, the four UK nations (England, Northern Ireland,
Scotland, and Wales), nine Canadian provinces (Alberta, British Columbia, Manitoba, New Brunswick, Newfoundland
and Labrador, Nova Scotia, Ontario, Prince Edward Island, and Saskatchewan), and two Australian states
(New South Wales and Victoria). Patients aged 15–99 years diagnosed with cancer in eight different sites (oesophageal,
stomach, colon, rectal, liver, pancreatic, lung, or ovarian cancer), with no other primary cancer diagnosis occurring
within the 5 years before to 1 year after the index cancer diagnosis or during the study period were included in the
study. We examined variation in radiotherapy use from 31 days before to 365 days after diagnosis and time to its
initiation, alongside related variation in patient group differences. Information was obtained from cancer registry
records linked to clinical or patient management system data, or hospital administration data. Random-effects metaanalyses quantified interjurisdictional variation using 95% prediction intervals (95% PIs).
Findings Between Jan 1, 2012, and Dec 31, 2017, of 902 312 patients with a new diagnosis of one of the studied
cancers, 115 357 (12·8%) did not meet inclusion criteria, and 786,955 were included in the analysis. There was large
interjurisdictional variation in radiotherapy use, with wide 95% PIs: 17·8 to 82·4 (pooled estimate 50·2%) for
oesophageal cancer, 35·5 to 55·2 (45·2%) for rectal cancer, 28·6 to 54·0 (40·6%) for lung cancer, and
4·6 to 53·6 (19·0%) for stomach cancer. For patients with stage 2–3 rectal cancer, interjurisdictional variation was
greater than that for all patients with rectal cancer (95% PI 37·0 to 84·6; pooled estimate 64·2%). Radiotherapy use
was infrequent but variable in patients with pancreatic (95% PI 1·7 to 16·5%), liver (1·8 to 11·2%), colon (1·6 to 5·0%),
and ovarian (0·8 to 7·6%) cancer. Patients aged 85–99 years had three-times lower odds of radiotherapy use than
those aged 65–74 years, with substantial interjurisdictional variation in this age difference (odds ratio [OR] 0·38;
95% PI 0·20–0·73). Women had slightly lower odds of radiotherapy use than men (OR 0·88, 95% PI 0·77–1·01).
There was large variation in median time to first radiotherapy (from diagnosis date) by cancer site, with substantial
interjurisdictional variation (eg, oesophageal 95% PI 11·3 days to 112·8 days; pooled estimate 62·0 days; rectal
95% PI 34·7 days to 77·3 days; pooled estimate 56·0 days). Older patients had shorter median time to radiotherapy
with appreciable interjurisdictional variation (−9·5 days in patients aged 85–99 years vs 65–74 years, 95% PI
−26·4 to 7·4).
Interpretation Large interjurisdictional variation in both use and time to radiotherapy initiation were observed,
alongside large and variable age differences. To guide efforts to improve patient outcomes, underlying reasons for
these differences need to be established.