Oh, absolutely. Biomagnification is inherent to the logic of raising through the trophic levels. So even if we forego the zoo experiment as a setting, in theory any time there's a toxin or a man-made hazardous chemical due to pollution in the wild, we are bound to find higher levels of either due to the concentration effect alone.

We can even point that back to the study, as the zoo animals were eating domestic raised animals by humans and the inherent hazards of that practice surely increase the risk of cancer, not lower it. Maybe they can even start a lab grown meat trial with carnivorous zoo animals and see if the cancer rate actually lowers from that alone. In theory, it should.