The cause of azoospermia and atrophic testes are many and most of the times not known - it can occur because of trauma, infection or can be due to a genetic abnormality. You need to be seen by a urologist who would examine you and suggest the best course of action. Even in atrophic testes sometimes sperms can be found on biopsies and they can be used for a test tube baby. The risk of cancer is increased as compared with people with normal testes, you should be examined by a urologist annually to detect any abnormal growth, overall the chances of cancer are low.