Men can screen themselves by feeling for lumps in their testicles. Men between 25 and 45 should do this every few months. If a lump is found on one testicle, check the other one to see if the same lump is present. If there are similar lumps on both, then it is almost certainly a normal part of the testicles. If the lump is only on one testicle, you should consult your doctor.