Lost a lot o good friends from my youth in the last 10yrs to lung and throat cancer and after around 4months into treatment dvla has taken their licences, my best mate thought he was cured of cancer of the thorax after a huge operation but its returned after 9months into cancer of the spine ,he just had licence returned but now its away again for good 
. AS I drove tippers wae most o them I had myself checked late last yr,after I mentioned this to my doctor seems I am ok at the moment but seems a strange co incident so many ex workmates coming down with this horrible thing!. (my friends are in the uk). good luck mate.