As a person with cancer going through treatment, even with fully paid for by my employer healthcare and making a good amount of money, this is super expensive and if I didn't have a job where I could work remote, I'd probably be bankrupt by now with all the time I have to spend in treatment and the initial surgeries.

5 year survival rates vary by the type of cancer, while cancers like leukemia, prostate, and breast cancer have made progress, most of those survival rate numbers are based on catching the cancer early, which, unfortunately most aren't caught early leading to a poor prognosis, my prognosis for example is 5% overall survival for 5 years with a significant drop off after 3 years. The survival rate is also heavily dependent on comorbidities, or other things that impact your health, this can leave things like surgery off the table.

Another fun fact is that we really still suck at cancer treatment because we don't know how it functions, and as previously stated there's over 100 different types of cancer, each with their own mechanisms and subtypes.

So to your main point, no unless there's some massive breakthrough in immunotherapy that's pan-cancer responsive for most patients (right now immunotherapy only works for roughly 20-30% of patients), the costs aren't going to go up dramatically as the primary option is surgery if it's early and if it's late you're probably still going to be dead within 5 years. The number of patients surviving each year only goes up by about roughly 2% per year.