I have always wondered if my husbands cancer on his larynx which is very rare could of stemmed from a chemical exposure. Last May he was cleaning out some clogged kitchen pipes and had used a strong drain opener, somehow this came in contac with bleach and he must of inhaled a good bit. I remember him calling me and saying he about killed himself, he had gone outside and coughed and gagged for a half hour. This was May and a few months later, August his voice was having issues which led him to the ENT and was diagnosed with cancer. I don't know if it makes a big difference on what led to the start of cancer but maybe if it was environmental and it has been removed and treated with rads and chemo it might not return whereas if it something in his body chemistry it may have the possibly of recurring. Just something I have wondered and maybe someone may have some insight.