There is no advertising money in those fields.
Starting salary for a postdoc is a bit less than $50k, and this is after 5+ years of grad school, during which you make even less (often $20-30k) One can expect to be a postdoc for 3-5+ years before becoming remotely competitive for an independent (faculty) position, and another 5 years before the job is relatively secure. The competition for these jobs—and the remaining industrial ones—is savage and unpredictable.
This is bad for so many reasons: frantic people don’t do careful experiments or do good science, very smart people opt out all together and figure out how to make you click on ads instead, and a lot of time, money, and effort gets wasted in the churn.
If you want more cancer research and less ad optimization, nag your reps to improve how we fund research!