Michael Douglas went on Letterman Tuesday and talked about the recent news that he has throat cancer. He has just completed his first of eight weeks of radiation and chemotherapy, and appeared a little thinner than usual, with his suit slightly oversize. With the coming weeks of treatment, he said, his voice may change and it could become impossible to swallow solid food.But he was upbeat, saying that despite his throat cancer being Stage 4, it has not spread down below his throat.