In the US, we have a nationwide public healthcare system called “Medicare”. You generally only qualify for Medicare once you’re 65 except in special circumstances. Many of our citizens can’t afford to be diagnosed with cancer at an earlier age, as it will increase their non-Medicare private insurance premiums^, result in denied coverage for unrelated issues, and potentially send them into bankruptcy if treated. So they wait until they turn 65, and only then bring in pre-existing conditions for diagnosis and treatment, confident that they can no longer be bankrupted by doing so.
^ Insurance premiums average $300-$700 USD per month per person nationwide, when not available through full-time employment or (65+) Medicare. ~75.000.000 US citizens age 18-64 are employed full-time, which compels their employers to subsidize their monthly health insurance costs; the remaining ~127.000.000 citizens are not employed full-time and thus do not qualify for mandatory employer-provided insurance.
EDIT - Military veterans, poor people, and so on often have access to additional free public health systems other than Medicare, offered either nationwide or by member states of our union or by non-governmental organizations; degree of subsidy and quality of coverage varies wildly among them.
# The above estimates were constructed using napkin math and the below links.
“Average Monthly Benchmark Plan Premiums for a 27-Year-Old in Plan Year 2020 in Healthcare.gov States” https://www.investopedia.com/how-much-does-health-insurance-...
"Population estimates": https://www.census.gov/quickfacts/fact/table/US
"The U.S. labor force": https://en.wikipedia.org/wiki/Labor_force_in_the_United_Stat...