The probability to detect a tumor with such method in asymptomatic subjects is lower than 1%. In many cases, the diagnoses deal with indolent tumors (i.e., low grade lymphomas) which do not benefit from early therapy, or far advanced and untreatable (although silent) tumors (i.e., pancreatic cancer). False positive results predominate (mainly in the head-neck region), bringing about extra examinations and unnecessary (so harmful) biopsies and surgical procedures. Like all the other diagnostic methods, PET/TC must be used in front of clear questions and definite clinical settings.