Survival is a key measure of the effectiveness of cancer patient care. Survival has been improving for many cancers, and Australia has among the highest cancer survival in the world. However, there are known disparities in cancer survival across small areas in Australia, with remote areas commonly having lower survival than urban areas. It was unclear how these disparities differed across time.
To understand how small area patterns changed over time for two commonly diagnosed cancers in Queensland, Australia: breast and colorectal cancer.
Using routinely collected data from the Queensland Cancer Registry, we examined breast and colorectal cancer cause-specific survival using flexible parametric models for cancers diagnosed during 1996-2010 and followed up to the end of 2011. The risk of death within five years was examined across three different time periods (1996-2000, 2001-2005 and 2006-2010) and 478 statistical local areas in Queensland. Models were adjusted for age, tumour stage at diagnosis, and for colorectal cancer, sex. Modelling was conducted within a Bayesian framework to enable robust and reliable estimates to be obtained.
Consistent improvement in survival was seen across all small areas, for both breast and colorectal cancer. After adjusting for tumour stage, colorectal cancer survival continued to show improvement in both time periods, while breast cancer survival only improved in the most recent time period. Despite the state-wide improvements in survival, patients residing in more remote areas had poorer survival than those residing in urban areas for both breast and colorectal cancer.
Improvements in survival are being shared equally across Queensland for breast and colorectal cancer patients. However, important survival disparities remain for cancer patients living outside of urban areas.