I personally know a couple people who went blind from looking at radio sources (one was a wave-guide the other was a radar dish; oops). That's one reason I never watch my food cook in a microwave.

As a kid we used to cook hotdogs using an antenna and transmitter.

So yeah, radio waves can have an effect on you no doubt. As for cancer, well, anything that damages your cells theoretically has a chance at cancer. Whether that risk is higher than normal with common radio sources like cellphones is up for debate but I think it's possible.

Edit: Most Wifi is very weak so at even a small distance unlikely to damage cells. Cellphones can be more powerful and you hold it right up against your body. Does it actually damage cells? I think the jury is still out but again I think it's possible..