[geoffjentry]

Because the patient would still wind up living longer than they would have otherwise. Would you rather die of cancer in six months or from a different cancer 10 years from now? Many people would prefer the latter.

[Kaibeezy]

Ah, of course, there would be a delay. Would a lag of several years be common, or could be much shorter / longer?

[geoffjentry]

It's not that straightforward.

One thing to consider though is that 5 year survival is often used as a measuring stick on treatments in cancer. So events within those 5 years would count against the treatment.