How Often and How Quickly Is Radiotherapy Used for Eight Common Cancers? A Major International Comparison

Table of Contents

• Key Points
• Background: Why This Research Matters
• How the Study Was Conducted
• Key Findings: How Much Radiotherapy Use Varied
• Key Findings: How Long Patients Waited for Radiotherapy
• Age and Sex Differences in Radiotherapy Use
• What These Findings Mean for Patients
• Limitations: What the Study Could Not Prove
• Recommendations and Next Steps
• Frequently Asked Questions
• Source Information

Key Points

• In 786,955 patients diagnosed 2012–2017 across Norway, the UK, Canada, and Australia, radiotherapy use varied widely between regions for eight common cancers.
• For oesophageal cancer, radiotherapy use ranged from 17.8% to 82.4%; for stomach cancer, from 4.6% to 53.6%.
• Patients aged 85–99 were about three times less likely to receive radiotherapy than those aged 65–74, with this age difference varying between regions.
• Median time from diagnosis to first radiotherapy ranged from 11.3 to 112.8 days for oesophageal cancer and 34.7 to 77.3 days for rectal cancer.
• The authors conclude the reasons for these differences must be identified to improve patient outcomes, and recommend surveillance of treatment patterns.

Background: Why This Research Matters

Cancer survival differs between countries. One possible reason is that patients in different countries receive different treatments, or receive them at different speeds. Radiotherapy (treatment using high-energy radiation to kill cancer cells) is a key treatment for many patients with cancer. Whether radiotherapy is appropriate depends on the cancer site, the disease stage, and the patient's overall health and ability to carry out daily activities (performance status).

Previous research has found differences in radiotherapy use between patient groups and between regions within single countries. However, comparisons between multiple countries are rare. Health needs for radiotherapy are often not met, and radiotherapy services and research are often under-resourced.

When radiotherapy is given before surgery (neoadjuvant) or after surgery (adjuvant), starting treatment sooner matters for the patient experience. Shorter waiting times also signal that a health system has enough capacity and works efficiently. Many countries track waiting times as a performance measure, but evidence comparing waiting times between countries is scarce.

This study is part of the International Cancer Benchmarking Partnership (ICBP). The ICBP is a collaboration of clinicians, policymakers, researchers, and data experts in seven countries: Australia, Canada, Denmark, Ireland, New Zealand, Norway, and the UK. The partnership aims to explain differences in cancer survival between high-income countries. All these countries have comprehensive cancer registries, similar health system spending, and universal health care.

The researchers examined international variation in overall radiotherapy use and in the time to first radiotherapy treatment. They also examined how these measures varied by age group, sex, and cancer site. The goal was to take a step toward a more detailed understanding of international variation in cancer treatment.

How the Study Was Conducted

This was a population-based study, meaning it included all eligible patients in the participating regions rather than a selected sample. The data came from Norway and the four UK nations: England, Northern Ireland, Scotland, and Wales. The data also came from nine Canadian provinces: Alberta, British Columbia, Manitoba, New Brunswick, Newfoundland and Labrador, Nova Scotia, Ontario, Prince Edward Island, and Saskatchewan. The data also came from two Australian states: New South Wales and Victoria.

All these regions have high-quality population-based cancer registries. Information on radiotherapy use came from cancer registry records. These records were linked, where applicable, to clinical or patient management system data, or to hospital administration data.

Who was included: Patients were eligible if they had a new primary diagnosis of one of eight cancers:

• Oesophageal cancer (cancer of the food pipe)
• Stomach cancer
• Colon cancer (large bowel cancer)
• Rectal cancer (back passage cancer)
• Liver cancer
• Pancreatic cancer
• Lung cancer
• Ovarian cancer

Patients had to be aged 15–99 years at diagnosis. They could not have another primary cancer diagnosis within 5 years before to 1 year after the index cancer diagnosis, or during the study period. Patients registered solely from a death certificate were excluded. For ovarian cancer only, patients with discordance between cancer site and sex were also excluded.

Patients were diagnosed between Jan 1, 2012, and Dec 31, 2017. Study periods varied slightly between regions because of differences in data availability.

How radiotherapy use was defined: The researchers counted a patient as having received radiotherapy if there was at least one administration (fraction) of radiotherapy from 31 days before to 365 days after the date of diagnosis. Including a month of observation before the registered diagnosis date allowed the study to capture neoadjuvant radiotherapy that started before the final tissue-based (histological) diagnosis. This situation occurred in fewer than 5% of all cases across all regions.

All patients were followed up for up to 1 year after diagnosis, or until death if death occurred earlier. This follows the standard practice used by the participating cancer registries.

How the analysis was done: The study used a federated or distributed analysis model. Standardised patient-level datasets were first specified in advance. Each participating region then created and quality-assured its own dataset in a local analytical hub. This step included assessing likely sources of bias and checking the distribution of key variables. It helped identify and correct occasional coding errors or misspecifications in regional datasets. Regional team coauthors identified potential quality problems in local data.

Data were analysed within each hub using centrally developed R Markdown code. Only aggregate, group-level data suitable for publication were shared with the central team. No patient-level data were transferred between regions.

Statistical methods: Random-effects meta-analyses characterised variation between regions. The researchers calculated 95% prediction intervals (95% PIs). A 95% PI shows the range of outcomes that would be expected in similar regions not included in the analysis. The researchers also reported tau values, which represent the standard deviation and give a direct measure of how large the variation between regions was.

For radiotherapy use, the meta-analyses covered the percentage of patients treated with radiotherapy. This was calculated for all eight cancer sites together and for each site separately, using observed values without adjustment for case mix. The analyses also covered the odds ratios (ORs) of radiotherapy use by sex (female compared with male) and by age group. The age groups were 15–64 years, 75–84 years, and 85–99 years, each compared with 65–74 years, which was the most common age group in the analysis sample. These odds ratios were adjusted for sex, age group, cancer site, and diagnosis year.

For time to first radiotherapy, the meta-analyses primarily considered the median time to first radiotherapy treatment from the diagnosis date. This was calculated for all eight cancer sites together and for each site separately, using observed values without case mix adjustment. The analyses also examined differences in median time to first radiotherapy by sex and by age group, adjusted for sex, age, cancer site, and diagnosis year.

The meta-analysis of the overall percentage of patients treated with radiotherapy assessed the log-odds of treatment, which were then converted back to the percentage scale. Meta-analyses of adjusted odds ratios used the model coefficients and standard errors reported by each region from regression models specified by the central team. For radiotherapy use, meta-analyses were fitted using restricted maximum likelihood with the R package metafor (version 3.4-0). For median time to radiotherapy, meta-analysis used the quantile estimation method, implemented in the R package metamedian (version 1.0.0).

Stage of diagnosis: Information was also available on stage at diagnosis, typically TNM stage (a standard system describing tumour size and spread). However, availability and completeness varied by region and cancer type. Stage information was incomplete for 17.4% (137,167) of patients in the analysis sample. Therefore, the primary analysis did not adjust for stage at diagnosis. The researchers also presented stage-adjusted odds ratios of radiotherapy use by patient group for regions with high stage completeness (more than 70%) for every individual cancer site.

The researchers additionally examined radiotherapy use in patients with stage 2–3 rectal cancer. Rectal cancer was chosen because it had high completeness of stage information, and because indications for radiotherapy use in this patient group have long been established.

No information was collected on patients' race or ethnicity. No similar information was available on comorbidity (other illnesses), performance status, or treatment intent (neoadjuvant, adjuvant, curative, or palliative).

Ethics and consent: Primary data were collected under region-specific regulations that enable cancer registration and the collection of administrative data on hospital admissions or treatments. No participant consent was applicable. No identifiable data were shared for this project. In England, Northern Ireland, Scotland, Wales, British Columbia, New Brunswick, Newfoundland and Labrador, and Prince Edward Island, no additional approvals were necessary. This was given the nature of the study and its alignment with the routine surveillance function of cancer registries. In Ontario, approval came from a Research Ethics Board. In Saskatchewan, approval was obtained from the University of Saskatchewan Research Ethics Board. In Victoria, approval was granted for the data linkage and use of the Victorian data.

Key Findings: How Much Radiotherapy Use Varied

Between Jan 1, 2012, and Dec 31, 2017, there were 902,312 patients with a new diagnosis of one of the studied cancers. Of these, 115,357 (12.8%) did not meet the inclusion criteria. The final analysis included 786,955 patients.

The study found large variation between regions in how often radiotherapy was used. The 95% prediction intervals were wide for every cancer site. This means that if the same study were repeated in other similar regions, the results would be expected to fall across a broad range.

Here are the key results by cancer site, showing the range across regions (95% PI) and the pooled estimate (the average across all regions):

• Oesophageal cancer: range 17.8% to 82.4%; pooled estimate 50.2%
• Rectal cancer: range 35.5% to 55.2%; pooled estimate 45.2%
• Lung cancer: range 28.6% to 54.0%; pooled estimate 40.6%
• Stomach cancer: range 4.6% to 53.6%; pooled estimate 19.0%

For patients with stage 2–3 rectal cancer, the variation between regions was even greater than for all patients with rectal cancer. The range was 37.0% to 84.6%, with a pooled estimate of 64.2%. This finding is notable because stage 2–3 rectal cancer has well-established indications for radiotherapy.

Radiotherapy use was infrequent but still variable in several other cancer types:

• Pancreatic cancer: range 1.7% to 16.5%
• Liver cancer: range 1.8% to 11.2%
• Colon cancer: range 1.6% to 5.0%
• Ovarian cancer: range 0.8% to 7.6%

The researchers compared observed radiotherapy use against estimated population health need for radiotherapy by cancer site. These need estimates were based on evidence-based indications or comparative epidemiological data. The researchers did not attempt to formally identify regions with high or low radiotherapy use. They gave three reasons for this decision.

1. There is no global consensus about the best amount of radiotherapy use in a population. Such amounts cannot be inferred confidently without information on the use of other treatment methods and a range of tumour and patient characteristics.
2. Small differences between regions in how radiotherapy use was recorded might lead to large differences between specific regions. However, these small differences would have minimal effect on overall variation between regions.
3. The sample of regions was small. Therefore, the observed range between the participating regions cannot be assumed to represent the range across all high-income regions with universal health care coverage.

Estimates were not available because of small numbers for Prince Edward Island (for liver, pancreatic, and ovarian cancer) and Saskatchewan (for ovarian cancer). These region–cancer site groups, and their associated all-site-combined groups, were excluded from meta-analyses of overall use and overall time to radiotherapy. They were included in the analyses examining variation by age and sex.

A supplementary analysis examined the potential effect of differences in the age and cancer site composition of regional samples. This analysis fitted one-stage individual participant data meta-analysis models to the aggregate treatment use data.

Key Findings: How Long Patients Waited for Radiotherapy

There was large variation between regions in the median time to first radiotherapy from the diagnosis date. The median is the middle value: half of patients started radiotherapy sooner, and half started later.

For oesophageal cancer, the median time to first radiotherapy ranged from 11.3 days to 112.8 days across regions, with a pooled estimate of 62.0 days. For rectal cancer, the median time ranged from 34.7 days to 77.3 days, with a pooled estimate of 56.0 days.

Older patients had shorter median times to radiotherapy. Patients aged 85–99 years started radiotherapy 9.5 days sooner than patients aged 65–74 years. However, this age difference varied appreciably between regions, with a 95% prediction interval of −26.4 days to 7.4 days.

Age and Sex Differences in Radiotherapy Use

Age was strongly associated with whether a patient received radiotherapy. Patients aged 85–99 years had three times lower odds of radiotherapy use than those aged 65–74 years. The odds ratio was 0.38, with a 95% prediction interval of 0.20 to 0.73. This means the age difference itself varied substantially between regions.

Sex was associated with a smaller difference. Women had slightly lower odds of radiotherapy use than men. The odds ratio was 0.88, with a 95% prediction interval of 0.77 to 1.01. Because this interval crosses 1.0, the difference between women and men was not statistically significant across the studied regions.

What These Findings Mean for Patients

This is the first study to establish the frequency of radiotherapy use in patients diagnosed in the last decade with these eight common cancers across multiple international regions. This is also the first study to establish time to radiotherapy initiation in these patients. The study identified wide variation in radiotherapy use and in age-related disparities. These differences followed broad patterns by region.

The findings highlight the value of including measures of radiotherapy use in international studies that compare cancer treatment and outcomes. They also support introducing population-based surveillance of treatment patterns and related disparities, both within and between countries.

The results show that where a patient lives may influence whether they receive radiotherapy and how quickly they receive it. For example, a patient with oesophageal cancer in one region might have a 17.8% chance of receiving radiotherapy, while a similar patient in another region might have an 82.4% chance. This variation was observed even for stage 2–3 rectal cancer, where radiotherapy indications are well established.

The study also shows that older patients are consistently less likely to receive radiotherapy than younger patients. The size of this age difference varied substantially between regions. This suggests that non-medical factors, such as regional practice patterns, may influence treatment decisions for older patients.

The authors state that the causes of international variation in radiotherapy use need to be understood. They also note that the possible implications of this variation for patient outcomes and international differences in cancer survival need to be examined.

Limitations: What the Study Could Not Prove

The study had several limitations that patients and clinicians should keep in mind.

First, the primary analysis did not adjust for stage at diagnosis. Stage information was incomplete for 17.4% (137,167) of patients. Some of the variation between regions may reflect differences in how advanced cancers were when diagnosed, rather than differences in treatment practice.

Second, no information was available on comorbidity, performance status, or treatment intent. These factors affect whether radiotherapy is appropriate for an individual patient. Without this information, the researchers could not fully account for differences in patient health between regions.

Third, the study did not collect information on patients' race or ethnicity.

Fourth, the researchers did not attempt to identify which regions had high or low radiotherapy use. There is no global consensus on the best amount of radiotherapy use in a population. Such amounts cannot be inferred confidently without information on other treatments and detailed tumour and patient characteristics.

Fifth, small differences between regions in how radiotherapy use was recorded might lead to large differences between specific regions. However, these small differences would have minimal effect on overall variation between regions.

Sixth, the sample of regions was small. The observed range between the participating regions cannot be assumed to represent the range across all high-income regions with universal health care coverage.

Finally, the results are likely to apply to regions with high Human Development Index values and universal health care coverage. They may not apply to other settings.

Recommendations and Next Steps

The authors recommend that future work should examine the tumour, patient, and health-care factors that underlie radiotherapy use in different countries and health systems. Health-care factors to examine should include:

• Potential differences in clinical guidelines and how they are implemented
• Service organisation
• System capacity
• Health-care professional cultures
• Patient treatment preferences
• Access to clinical trial protocols

The authors also recommend incorporating measures of radiotherapy use into both international comparative survival studies and routine cancer surveillance within countries. They state that the underlying reasons for the differences observed in this study need to be established to guide efforts to improve patient outcomes.

For patients, the key message is that radiotherapy use and waiting times vary widely between regions for the same cancer types. If you have questions about whether radiotherapy is right for you, or about how long you may wait for treatment, speak with your cancer care team. The study findings support asking about the reasons behind treatment decisions and about the expected timeline for starting radiotherapy.

Frequently Asked Questions

What did this study look at?

It compared how often radiotherapy was used and how quickly it was started for patients with eight common cancers. The study covered Norway, the four UK nations, nine Canadian provinces, and two Australian states. It included 786,955 patients diagnosed between 2012 and 2017. The authors conclude that the reasons behind the differences found must be identified to improve patient outcomes.

Which cancers were included?

The study included eight cancers: oesophageal, stomach, colon, rectal, liver, pancreatic, lung, and ovarian. Patients were aged 15–99 at diagnosis and had a new primary diagnosis of one of these cancers. They could not have another primary cancer diagnosis within a set time around the diagnosis. Patients registered solely from a death certificate were excluded.

How much did radiotherapy use vary between regions?

Radiotherapy use varied widely. For oesophageal cancer, it ranged from 17.8% to 82.4% across regions. For stomach cancer, it ranged from 4.6% to 53.6%. For stage 2–3 rectal cancer, where radiotherapy indications are well established, it ranged from 37.0% to 84.6%. The authors say the reasons for these differences need to be identified.

Did older patients receive radiotherapy less often?

Yes. Patients aged 85–99 were about three times less likely to receive radiotherapy than those aged 65–74. The odds ratio was 0.38, with a wide prediction interval of 0.20 to 0.73, meaning the age difference itself varied substantially between regions. The authors suggest non-medical factors, such as regional practice patterns, may influence treatment decisions for older patients.

How long did patients wait for radiotherapy?

Waiting times varied widely between regions. For oesophageal cancer, the median time from diagnosis to first radiotherapy ranged from 11.3 to 112.8 days across regions. For rectal cancer, it ranged from 34.7 to 77.3 days. Older patients started radiotherapy sooner on average, but this age difference also varied between regions.

What are the limitations of this study?

The main analysis did not adjust for stage at diagnosis, which was incomplete for 17.4% of patients. No information was available on other illnesses, performance status, or treatment intent. The study did not collect race or ethnicity data. The sample of regions was small, so the observed range may not represent all high-income regions with universal health care.

What should patients take away from this research?

The findings show that where a patient lives may influence whether they receive radiotherapy and how quickly. If you have questions about whether radiotherapy is right for you, or about how long you may wait, speak with your cancer care team. The authors recommend asking about the reasons behind treatment decisions and the expected timeline for starting radiotherapy.

Should I get a second opinion if I have oesophageal cancer and I'm not sure whether radiotherapy is right for me?

Radiotherapy use for oesophageal cancer ranged from 17.8% to 82.4% across regions, and median time to first radiotherapy ranged from 11.3 to 112.8 days. Patients aged 85–99 had about three times lower odds of receiving radiotherapy than those aged 65–74. Because where a patient lives may influence whether and how quickly radiotherapy is given, a second opinion can help clarify whether radiotherapy is appropriate for your cancer site, stage, and overall health, and what timeline to expect. Diagnostic Detectives Network provides independent expert second opinions.

Source Information

Original article title: 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

Authors: Sean McPhail, Matthew Barclay, Ruth Swann, Shane A. Johnson, Riaz Alvi, Andriana Barisic, et al.

Publication details: Lancet Oncology 2024; 25: 352–65. Published by Elsevier Ltd. This is an Open Access article under the CC BY 4.0 license.

Funding: International Cancer Benchmarking Partnership, funded by the Canadian Partnership Against Cancer, Cancer Council Victoria, Cancer Institute New South Wales, Cancer Research UK, Danish Cancer Society, National Cancer Registry Ireland, The Cancer Society of New Zealand, National Health Service England, Norwegian Cancer Society, Public Health Agency Northern Ireland on behalf of the Northern Ireland Cancer Registry, DG Health and Social Care Scottish Government, Western Australia Department of Health, and Public Health Wales NHS Trust.

This patient-friendly article is based on peer-reviewed research.