Figures from Consumers Health Forum of Australia (CHFA) showed that nearly half of Australian cancer patients paid more than $5,000 in out-of-pocket expenses for their treatment over a two-year span; a quarter spent more than $10,000. The 2018 report, which was the most recent data we could find, can be read here.
Costs can vary quite a bit based on where you live, your individual illness, the treatment needed and recovery time.