Feature: National cancer stage at diagnosis data
Introduction
Australia has had high quality data on cancer incidence, mortality and survival over many years through the efforts of state and territory cancer registries, and the Australian Institute of Health and Welfare (AIHW). However, until now we have not been able to provide national information about the ‘stage at diagnosis’ (that is, the extent to which a cancer has spread when first diagnosed). Stage is broadly categorised into four stages of increasing severity, with Stage 1 being localised disease and Stage 4 being metastatic or more widely spread disease.
The lack of national cancer staging data has been an identified gap in our data knowledge in Australia. Knowing the distribution of stage at diagnosis is crucial to understanding variations in survival, and can help inform where further research and targeted cancer control strategies can be applied to reduce the proportion of cancers diagnosed at an advanced stage. The national collection and reporting of cancer stage at diagnosis forms part of Cancer Australia’s Stage, Treatment and Recurrence (STaR) project.
For the first time in Australia, national data are presented on cancer stage at diagnosis for the top five incident cancers: breast (female), colorectal, lung and prostate cancers, and melanoma. The staging data has been generated by all state and territory population-based cancer registries using endorsed national business rules, and this Registry-derived stage at diagnosis is henceforth referred to as ‘stage’. The stage data was collated and provided to Cancer Australia by the AIHW.
Australia is among the first countries world-wide to report comprehensive national stage at diagnosis data.
A detailed examination of the data, including information about data sources, methods for collection, and guidance for interpretation are available in the following measures:
A high proportion of cancers were staged and most cancers tended to be diagnosed at an early stage
Using agreed Business Rules, Australian cancer registries are able to determine stage at diagnosis for a high proportion of the top five cancers
- At least 94% of incidence cases were able to be staged, for melanoma (97%), prostate (97%), and breast (female) cancer (94%).
- Lower staging completeness was found for colorectal (88%), and lung cancers (72%).
Some registries do not have access to information such as imaging records, and these records can affect the ability to stage cancers. For cancers, such as lung cancer, where surgical resections and pathology review may not take place, imaging records are an important source of information on which to derive stage at diagnosis.
The majority of cancers were staged as an ‘early stage’ at diagnosis for each cancer type, except for lung cancer.
Stage at diagnosis can broadly be categorised into four stages of increasing severity (Stages 1, 2, 3 and 4).
- At least three-quarters of cases were diagnosed as early stage (stage 1 or stage 2) for breast (female) (77%) and prostate cancers (82%), and melanoma (92%) (see Figure below). There were lower proportions of advanced cancers (stage 3 and stage 4) at diagnosis for breast (female) (17%) and prostate cancers (16%), and melanoma (5%).
- For colorectal cancers, similar proportions of cancers were stage 1, 2, or 3 (around 24% for each) at diagnosis but there was a slightly lower proportion of stage 4 cancers (18%).
- More than half (53%) of lung cancer cases were of a more advanced stage at diagnosis, (stage 3, 11%; stage 4, 42%). This may be an underestimate as 29% of lung cancers were of unknown stage.
Stage for the top 5 incidence cancers in 2011:
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