Descriptive epidemiological study of rare, less common and common cancers in Western Australia

Gemma A Bilkey,Jennifer Girschik,Richard W Trevithick,Emily P Coles,Kristen J Nowak

doi:10.1186/s12885-021-08501-4

Gemma A Bilkey, Jennifer Girschik + Show 3 more

Open Access

https://doi.org/10.1186/s12885-021-08501-4

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Abstract

BackgroundThere are no epidemiological studies describing rare cancers in Western Australia (WA). We aimed to fill this gap by estimating the incidence and five-year survival of rare, less common and common cancers in WA, based on definitions for rarity used by the Australian Institute of Health and Welfare and cancer groupings from the project on Surveillance of Rare Cancers in Europe (RARECARE). This research will enable policy- and decision-makers to better understand the size and nature of the public health problem presented by rare cancers in WA. It is anticipated that this study will inform improved health service design and delivery for all WA cancer patients, but particularly those with rare and less common cancers.MethodsWe estimated incidence and five-year survival rates of rare, less common and common cancers in WA using data sourced from the WA Cancer Registry for the 2013–2017 period. Cancers were defined as rare (< 6), less common (6–12), or common (> 12) based on their crude incidence rate per 100,000 people per year.ResultsRare cancers make up 21.5% of all cancer diagnoses in WA, with a significantly poorer five-year survival of 58.2% (95% confidence interval (CI) 57.3–59.1%), compared to patients diagnosed with a common cancer, whose five-year survival was 87.8% (95% CI 87.3–88.3%). Survival for less common cancers was significantly poorer than both rare and common cancers, at 48.1% (95% CI 47.3–49.0%). Together, rare and less common cancers represent 48.4% of all cancer diagnoses in WA.ConclusionsWhile rare cancers are individually scarce, collectively over one in five cancer patients in WA are diagnosed with a rare cancer. These patients experience significantly worse prognoses compared to patients with common cancers.

Highlights

There are no epidemiological studies describing rare cancers in Western Australia (WA)
The aims of this paper are to: 1) develop the first comprehensive list of clinically distinct rare, less common and common cancers for an Australian jurisdiction by defining unique cancers according to the RARECARE groupings and using the rarity definitions adopted by the Australian Institute of Health and Welfare (AIHW) [22], 2) describe the demographic characteristics of people with rare cancers, 3) compare the demographic characteristics of people with rare, less common and common cancers, and 4) estimate five-year survival from rare cancers in WA
Our results suggest that Aboriginal people with a cancer diagnosis are more likely to be diagnosed with a rare cancer than non-Aboriginal people

Summary

Introduction

There are no epidemiological studies describing rare cancers in Western Australia (WA). There have been no studies investigating the descriptive epidemiology of rare cancers in Western Australia (WA) compared to less common and common cancers. Classification There is no universally-agreed definition for what constitutes a rare cancer. The project on Surveillance of Rare Cancers in Europe (RARECARE) uses a definition of < 6 incident cases per 100,000 people per year while the United States (US) National Cancer Institute uses a definition of < 15 incident cases per 100,000 people per year [2, 3]. A frequency definition may mean lists of rare cancers developed in one region are inconsistent with other regions with different demographic profiles and could lead to different cut-off points, further hampering comparability. The methods used to identify individual cancer entities (e.g., topography and/or morphology) influence the frequency of unique cancers and the number and type of cancers classified as rare

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