Thankfully we do not know of any airborne cancer, as Peter said cancer is where cells of host organism replicate out of control and so it is more a problem with the host animals than with an infectious disease. However some diseases do lead to an increased risk of cancer and catching these diseases mean that people have to be more vigilant.
Where I have to disagree with Peter is that there is in fact an infectious form of cancer that affects Tasmanian Devils I have the Wikipedia link here. http://en.wikipedia.org/wiki/Devil_facial_tumour_disease
While this is not airborne it is an extremely scary discovery, for most of the history of cancer research people were confident that it could not be transmitted directly from person to person (though diseases that might make you more likely to develop cancer can be transmitted). We do think that Devil facial tumour disease (the cancer) is only able to transmit from Devil to Devil and this makes sense since cancer cells to be able to grow in the new animals would need to be very like the cells already there (they would need to be able to get nutrients and to grow) so at the moment we don’t think this is likely to ever happen in humans. Humans have a lot more diversity between individuals than there is in the Tasmanian Devils so cells from one person might never be able to grow within another person.