Its cause is not known, but men who have had undescended testicles and those with a close male relative who had testicular cancer are more at risk of developing it. Early detection means it's curable, so self-examination needs to be a monthly routine. Robbie Williams does it and so should every man. Some say they're embarrassed, some are frightened of finding anything wrong. Others remember sporting days where any testicular contact was associated with excruciating pain and believe quite wrongly that self-examination will be painful.
Some men leave it to their partners to take the responsibility.
Often it's a woman who discovers the problem and sends her man to the doctor. Many men say they're not sure how to examine themselves or what to look out for. The key is to get to know what your testicles feel like normally by examining them monthly. If you're not sure what they're supposed to feel like then ask your doctor to examine you. Use this as a baseline of what's normal for you because what you're checking for is anything that doesn't feel right or is different to normal.