Differences in cancer survival by remoteness of residence: an analysis of data from a population-based cancer registry

Our plain-English summary of Differences in cancer survival by remoteness of residence: an analysis of data from a population-based cancer registry, by N. Afshar, D.R. English, J.A. Chamberlain, et al (Cancer Causes & Control, 2020).

The study

• Authors: N. Afshar, D.R. English, J.A. Chamberlain, T. Blakely, V. Thursfield, H. Farrugia, G.G. Giles, R.L. Milne
• Journal: Cancer Causes & Control
• Published: 2020;31(7):617-629
• Cited by: 12 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Purpose: Cancer survival is generally lower for rural compared with urban residents, but findings have been inconsistent. We aimed to assess inequalities in cancer survival by remoteness of residence in Victoria, Australia.

Methods: Incident cancer cases diagnosed in 2001-2015 with 30 cancer types (n = 331,302) were identified through the Victorian Cancer Registry and followed to the end of 2015 through death registries. Five-year net survival was estimated using the Pohar-Perme method and differences assessed by excess mortality rate ratios (EMRRs) using Poisson regression, adjusting for sex, age and year of diagnosis. EMRRs adjusted for socio-economic disadvantage were also estimated.

Results: People living outside major cities had lower survival for 11 cancers: esophagus, stomach, colorectum, liver, gallbladder/biliary tract, pancreas, lung, connective/soft tissue, ovary, prostate, kidney. No differences in survival were found for cancers of uterus, small intestine and mesothelioma. After adjusting for socio-economic disadvantage, the observed differences in survival decreased for most cancers and disappeared for colorectal cancer, but they remained largely unchanged for cancers of esophagus, stomach, liver, pancreas, lung, connective/soft tissue, ovary and kidney.

Conclusion: People with cancer residing outside major cities had lower survival from some cancers, which is partly due to the greater socio-economic disadvantage of rural residents.

In plain English

This study used Victorian Cancer Registry records from Australia to compare cancer survival between people living in and outside major cities. It did not study asbestos exposure. Mesothelioma was one of 30 cancer types analysed. The authors included 331,302 people diagnosed in 2001 to 2015 (221,449 in major cities and 109,853 outside them) and followed them for up to five years. For 11 cancers, including lung, colorectal, pancreatic and prostate cancer, people outside major cities had lower survival, and the confidence intervals excluded no difference. For mesothelioma, the authors observed no evidence of a survival difference. Five-year net survival, not age-standardised, was 6.6% (95% CI 5.0 to 8.5) in major cities and 6.2% (4.1 to 8.9) outside them. After adjusting for area-level socio-economic disadvantage, the gap shrank for most cancers and disappeared for colorectal cancer. The authors concluded that people outside major cities had lower survival from some cancers, partly due to greater socio-economic disadvantage. They had no data on smoking, alcohol or moves after diagnosis. Without life tables for finer remoteness categories, they could not assess survival trends with increasing distance.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Population-based cancer registry study of survival (net survival and excess mortality rate ratios)
• Who was studied: 331,302 people aged 15 to 99 diagnosed with a first primary cancer (30 cancer types) in Victoria, Australia, between 1 January 2001 and 30 December 2015. Of these, 221,449 lived in major cities and 109,853 lived outside major cities.
• Exposure: Remoteness of residence at diagnosis (major cities versus outside major cities, using the Australian Bureau of Statistics remoteness structure). No asbestos or fiber exposure was studied.
• Main results:
  • For 23 of 30 cancer types, people living outside major cities had greater estimated excess mortality within five years of diagnosis.
  • For 11 cancers (esophagus, stomach, colorectum, liver, gallbladder/biliary tract, pancreas, lung, connective/soft tissue, ovary, prostate, kidney), the 95% confidence interval excluded no difference.
  • For mesothelioma, and for cancers of the uterus and small intestine, there was no evidence of a survival difference between people in and outside major cities.
  • Mesothelioma five-year net survival (not age-standardised) for people living in major cities: 6.6% (95% CI 5.0 to 8.5).
  • Mesothelioma five-year net survival (not age-standardised) for people living outside major cities: 6.2% (95% CI 4.1 to 8.9).
  • After adjusting for area-level socio-economic disadvantage, the survival disadvantage outside major cities decreased but persisted for most cancers, and disappeared for colorectal cancer.
  • For prostate cancer, the survival gap between people in and outside major cities increased over time.
• The authors' conclusion: The authors concluded that people with cancer living outside major cities had lower survival from some cancers than those in major cities, partly due to their greater socio-economic disadvantage.
• Limitations the authors state:
  • The registry had no information on health-related behaviours such as smoking or alcohol drinking.
  • The population life tables were not stratified by socio-economic disadvantage, Indigenous status or smoking, so bias from differences in background mortality cannot be ruled out.
  • Trends in survival with increasing distance from major cities could not be assessed, because life tables for finer remoteness categories (inner regional, outer regional, remote) were not available.
  • There was no information on changes of residence after diagnosis.
  • Using an area-level measure may misclassify individuals' socio-economic disadvantage.

Topics

Medical terms in this study, explained in our Lexicon: Cancer Registry, rate ratio, Mesothelioma, Colorectal Cancer.

Related studies

• Differences in cancer survival by sex: a population-based study using cancer registry data — N. Afshar, D.R. English, et al. (2018)
• Survival of solid cancer patients in France, 1989-2013: a population-based study — A. Cowppli-Bony, Z. Uhry, et al. (2017)
• Impact of malignant mesothelioma in Taiwan: a 27-year review of population-based cancer registry data — L.J. Lee, Y.Y. Chang, et al. (2010)
• Cancer survival and prevalence in Australia: period estimates from 1982 to 2010 — Australian Institute of Health and Welfare (2013)
• Is pleural infection associated with longer survival in mesothelioma? A population-based cohort study using data from Hospital Episode Statistics — A.C. Bibby, D. de Fonseka, et al. (2019)
• Malignant Peritoneal Mesothelioma: Patterns of Care and Survival in the Netherlands: A Population-Based Study — N.L. de Boer, J.P. van Kooten, et al. (2019)

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