12 approximately 1 in 14 men over the age of 50 has prostate cancer. the level of 'prostate specific antigen' (psa) is used as a preliminary screening test for prostate cancer 7% of men with prostate cancer do not have a high level of psa. these results are known as 'false negatives' 75% of those men with a high level of psa do not have cancer. these results are known as "false positives if a man over 50 has a normal level of psa, what are the chances that he has prostate cancer? a 7% b 25% c 5% d 07% 0.5%