I unfortunately can't find it, but there was an interesting chart that showed overall survival in metastatic colorectal cancer.
It covered the last 30 years. Each new therapy improved survival by only 6-12 months, but each new drug was more effective than the last. Over those 30 years, the median survival went from 6 months to over 5 years.
People shouldn't discount incremental improvements because that's often how medicine progresses.
