A huge part of that increase in 5 year survival rate is just earlier detection, though.

I fully acknowledge that we've made large strides in understanding and treating breast cancer, but in most cases, once it spreads it's still "game over", and so it is still an immensely fearful experience for people to go through. Contrast that with, for example, HIV. 35 years ago it was probably the scariest disease there was, considered a guaranteed death sentence. Now it is largely preventable with PrEP, and treatments are so good that it is a manageable condition with lifespans on par with HIV-negative people for most of those who diligently follow their treatments.