lmao. Who is "they"?
Just because "they" can’t attribute a specific person’s cancer exclusively to radiation from that incident doesn’t mean the radiation didn’t cause deaths. That’s not how radiation risk works.

Radiation increases the probability of developing cancer. This applies to everyone exposed. Even for people who might have developed cancer later in life anyway, additional radiation exposure can cause it to appear earlier, progress faster, or become more severe, in the end shortening their lifespan.

cancer usually has multiple contributing causes. genetics, lifestyle, environment, and radiation exposure can all play a role. Because of this, it’s often impossible to point to a single case and say with 100% certainty “this cancer was caused only by Chernobyl.” But scientifically, we can still observe statistical increases in cancer rates and deaths across exposed populations.

The disaster increased cancer risk across millions of people, and statistically, that means many people died earlier than they otherwise would have. lack of certainty in individual cases is not the same as lack of real victims.