There are lots of rumors swirling about Chester Bennington and throat cancer. But if you search online you can't really find anything but that: rumors. There are lots of people asking the question, but no one with a clear answer.
It's clear that he had some serious health problems a couple years ago, but it's unclear exactly what they were. And he has started a new band, Dead by Sunrise, so it seems like he's OK now. So, I'd say the connection between Chester Bennington and throat cancer is sketchy.