The Pap test (or Pap smear) is a screening test for early detection of precancerous changes in cervix , that might become cervical cancer if are not treated appropriately. It is recommended that all Women ages 21-65 should have a Pap smear on a regular basis. How often you do depends on your overall health and whether or not youve had an abnormal Pap smear in the past. HPV is the most common sexually transmitted infection (STI), and its linked to cervical cancer.