Earlier this week the U.S. Preventive Services Task Force shocked legions of women when it recommended waiting until 50 for a first mammogram, despite previous recommendations that women begin mammograms at 40. Then today, the American College of Obstetricians and Gynecologists released new guidelines for Pap smears. Previously, all sexually active women were encouraged to get the test—which examines cells in the cervix to determine whether there are any abnormalities that could lead to cancer—every year. Now, the recommendations state that women begin the Pap test at 21, retest every other year, and then, once women hit their 30s, schedule a test every three years.

Quite often, new technology hits the market before long-term studies have been completed, says Ted Epperly, a family physician and past president of the American Academy of Family Physicians. Only after years of using the equipment can experts then gather statistics about their efficacy. And, Epperly suggests, there may be other tests once considered annual necessities that are now being reevaluated in light of new evidence. We asked Epperly to evaluate other preventative tests—once considered lifesavers—and relay what the evidence currently suggests. As always, be sure to check with your doctor about your individual risks and treatment plan.

COLONOSCOPY

Both men and women are advised to have their first colonoscopy at 50, the American Cancer Society reports. In some cases, testing for colon cancer can be delayed until age 55, Epperly says. He goes on to warn that testing should not be delayed in instances where there is a family history of colon cancer or where a person experiences symptoms including weight loss, bloody stool, or unexplained abdominal pain. Colonoscopies have one of the highest success rates: they can reduce a person's chances of dying from colon cancer by between 60 and 70 percent.

PROSTATE SCREENING

The American Cancer Society reports that screenings should begin for men at 50. But just like mammograms, the final results can be misleading. Prostate-specific antigen (PSA) is a protein produced by the cells of the prostate gland, and a prostate screening test measures the level of this protein in a man’s blood. It’s possible for a man to have high levels of the protein in his system, but not actually have cancer. The National Cancer Institute reports that “only 25 to 35 percent of men who have a biopsy due to an elevated PSA level actually have prostate cancer.” It's also possible that the PSA can detect cancer so slow-moving that it likely would have gone undetected before the patient died of other causes.

The test is most useful for men who have a family history of prostate cancer or are experiencing symptoms like painful urination, weight loss, or pelvic pain. Black men are also encouraged to seek screening because they have a higher potential rate of prostate cancer. Evidence seems to indicate that men who don’t fall into any of these categories can forgo the prostate-cancer screening test, Epperly says.

CHEST X-RAY

As late as 2005, smokers were encouraged to get chest X-ray’s to detect any signs of lung cancer. But studies indicate the X-ray can produce misleading results. The U.S. National Cancer Institute conducted a study where 67,000 people received chest X-rays. The results showed abnormalities in nearly 6,000 cases, but after follow-up consultations with doctors, only 126 patients were actually diagnosed with lung cancer. Currently, no major professional organization, including the American Cancer Society, recommends routine screening because it hasn’t been shown to prevent people from dying of cancer.

FULL BODY SCAN

Total-body MRIs can also strain your wallet and cause unneeded anxiety. Popular in the past seven years as a general preventative tool, an MRI will produce images of anatomic abnormalities and is designed to help diagnose tumors, spinal-cord injuries, and problems with the lungs, kidneys, and uterus, the Mayo Clinic reports. However, MRIs often detect small irregularities that ultimately don’t require more testing or surgery. Epperly says patients often become more anxious when these irregularities are spotted and invest in costly medical exams to confirm that they are, in fact, healthy. Patients primarily need MRIs when a doctor is exploring a specific symptom, like whether excessive headaches might be the result of a tumor, Epperly says. Unless recommended by a doctor, total body images can be a serious financial burden, and may expose the patient to harmful radiation.