You're in luck! Since you're in Canada, 70% of the cost will be picked by the government, and that's if you don't have insurance which most employers do have for their employees, therefore cost is probably your least worries.
Canada picks up 100% of the cost of healthcare. The only costs the OP will have are medication, and losing income due to missed work.
I was under the impression that the exact arrangements vary by province in Canada.
Also, here in Australia we have both single payer (medical costs) and universal (hospital costs) healthcare but there are circumstances under which you might choose to go private and incur additional costs - either because you want to use a particular doctor and that doctor charges more than the government pays for a specific service or because you can get a particular procedure done faster by using the private system.
Again, the best way to get an idea of actual out of pocket costs is to talk to parents who've trodden this path before. For things not covered by the government, cancer organisations often subsidise the cost to some extent. The worst possible time to find out the cost of something isn't covered by the government is when you need it right now.
