Any electromagnetic radiation of considerable power and penetrability causes oxidative stress, which in turn causes cellular damage, which in turn increases probability of getting cancer.
So they are kind of right when they say that radiofrequency electromagnetic fields are possibly carcinogenic to humans. They are, but to a small degree for the most part.
The statement "radio can possibly cause cancer" is irrelevant if it takes a signal so powerful no human would ever encounter it, let alone produce it. The question is whether radio signals used in telecommunications can cause cancer, especially compared to the waves already present in nature.
The people most at risk would (one would think) be people that have a cellphone glued to their ear all day. But these people would (or: do) also end up with damage to their hearing, so maybe that tempers behavior ?
So they are kind of right when they say that radiofrequency electromagnetic fields are possibly carcinogenic to humans. They are, but to a small degree for the most part.