I am not from the US. Had my close relative fight with cancer. If not for the government which sponsored it almost fully, excluding a couple of procedures like PET, it would cost our family a lot. Just for the scale: pial for one infusion of one out of three drugs would cost us $8k and my relative would’ve needed 16 infusions.
So there is also an out of pocket maximum which is the most you’ll pay in a calendar year no matter how much your expenses are which vary by insurance plans but in my experience have generally been between 5-15k with 15k being for much cheaper insurance and 5k being for better insurance so if you have 1m in medical expenses and copay would be 200k it would instead be just that max out of pocket of approximately 10k, which while not great is much more manageable. The unfortunate thing is that is tied to the year so if you start treatment in November and finish treatment in March that 10k per calendar year turns into 20k since it was over the course of 2 years