http://www.bbc.co.uk/news/world-us-canada-29381978

That's bad luck.

I can't seem to find anything that says whether they are all dying of the same type of cancer. It's very sad that the legacy of that event is still claiming victims if they are related.

I would expect anyone who was there and who inhaled the dust to have an appreciably increased risk of respiratory illnesses including cancer. Given the age of the towers they would almost certainly have incorporated asbestos in the fabric of the building.

Not just asbestos (although obviously that's a major one). There are any number of materials used in construction that are really nasty when burning, and that's of the ones that they've tested. I'd imagine there were plenty of materials in the trade centre that we simply haven't tested being exposed to the temperatures that were in the the core of the fires. Who knows what effect the chemicals generated will have.