CatScan and disease prevention

I caught the health edition on the morning news and found that researchers have found that a full body CatScan can reveal early signs of heart, lung disease, colon cancer and who knows what else. GREAT
However, some critics believe that the testing may produce false alarms and may not be as accurate as claimed by the researchers?
Can anyone guess who the critics are? If you guessed the HMO's, you're probably right.