On the other hand you should by no means let your doctor decide everything, you need to be your own advocate for your own health and weigh in on making decisions regarding risk and benefits of treatments.
You need to be able to trust that your doctors guidance is genuinely what they feel is best based on their training and experience rather than a sponsored treatment they have been paid to prescribe.
I'm colored by just having heard https://www.numberphile.com/podcast/hannah-fry-orchid-cancer which was a podcast episode about cancer treatment and choices - and it says, there's more to it than this. Doctors may not value your life quality as high as you do etc.