Even if the absolute death rates for some cancers are relatively unchanged, one of the amazing things I’ve observed is that medical advances have increased the long term survival rates of terminal/metastaticized cancers. It’s partially due to the development of various drugs that have been identified as effective against various specific mutations. Even if the cancer is incurable with existing technology, they can extend lives by years, which is nothing to sneeze at. Especially considering many people get diagnosed with cancer once they are elderly already, it can mean the difference between dying directly of cancer and living long enough to die of something else - ie the cancer becomes something more like a chronic condition than it does a direct threat (for a period of time).