Forecasting of overall and aggressive prostate cancer incident counts at the small area level

This study aims to forecast overall and aggressive prostate cancer counts at the local government area (LGA) level over 10 years (2019-2028) in Victoria, Australia, using Victorian Cancer Registry (2001-2018) data.

We used the Age-Period-Cohort approach to estimate the annual age-specific incidence in each LGA and used Bayesian spatiotemporal models that account for non-linear temporal trends and area-level risk factors. We evaluated the models' performance by withholding and comparing forecasts with the 2014-2018 data.

There were 80,449 prostate cancer cases between 2001 and 2018, with an overall increasing trend. Compared to 2001, prostate cancer incidence increased by 69%, from 3049 to 5167 cases in 2018. Prostate cancer counts are expected to reach 7631 cases in 2028, a further 48% increase. Unexplained area-level spatial variation was substantially reduced after adjusting for the area-level elderly population. Aggressive prostate cancer cases increased by 107% between 2001 and 2018 and are expected to rise by 123% increase in 2028. The proportion of aggressive prostate cancer cases will increase to 31% in 2028 from 20% in 2018. By 2028, overall and aggressive prostate cancer cases are projected to be increasing in 66% and 61% of LGAs.

Prostate cancer cases are projected to rise at the state level and most LGAs in the next 10 years, with much steeper increases in aggressive cases. Population growth and an ageing population have primarily contributed to this rise besides prostate-specific antigen testing. These prediction estimates help inform prostate cancer burden and facilitate efficient healthcare delivery.