Use of Biomarkers in Screening for Cancer.

Screening for premalignant lesions or early invasive disease has the potential to reduce mortality from cancer. Because of their ease of measurement, several biomarkers have been evaluated or are currently undergoing evaluation as screening tests for early malignancy. These include the use of AFP in screening for hepatocellular cancer in high-risk subjects, CA 125 in combination with transvaginal ultrasound (TVU) in screening for epithelial ovarian cancer, PSA in screening for prostate cancer, faecal occult blood testing (FOBT) in screening for colorectal cancer (CRC) and vanillymandelic acid and homovanillic acid in screening for neuroblastoma in newborn infants, Of these biomarkers, only the use of FOBT in screening for CRC has unequivocally been shown to reduce mortality from cancer. Although 2 large randomized prospective trials have evaluated PSA as a screening test for prostate cancer, it is still unclear whether the benefits outweigh the harms in this setting. Although biomarkers have many attractive features as cancer screening tests, lack of sensitivity and specificity, when combined with the low prevalence of specific cancer types in asymptomatic subjects, limit their application for the early detection of malignancy.