Mammograms, colonoscopies, and Pap smears can save lives by providing critical early diagnoses of breast, colorectal, and cervical cancer. But eight other widely used cancer screenings — including those for prostate, bladder, and skin cancer — have been oversold, offer limited benefits, and should be avoided by most people.

Some may even do more harm than good.

 That’s the key conclusion of a new analysis by medical investigators with Consumer Reports magazine that raises significant questions about the value of many common cancer diagnostic tests that cost consumers and the U.S. healthcare system millions of dollars.

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Of 11 screenings evaluated, the magazine’s editors only recommended three — those for breast, colorectal, and cervical cancer — for individuals who are not at high risk and have no signs and symptoms of disease. The recommendations are based on an analysis of evidence-based reviews from the U.S. Preventive Services Task Force, an independent advisory group supported by the Department of Health and Human Services.   

“We know from our surveys that consumers approach screenings with an ‘I have nothing to lose’ attitude, which couldn’t be further from the truth,” said John Santa, M.D., director of CR’s Health Ratings Center.

“Unfortunately some health organizations have promulgated this belief, inflating the benefits of cancer screenings while minimizing the harm they can do,” he added, in comments released with the magazine’s findings. “To help clarify when most consumers should use cancer screenings and when they should skip them, we rate each screening and whether it is useful for a specific age group.  We also try to identify some high risk factors that may make screening a reasonable choice.” 

The review, published in the magazine’s March issue, noted even doctors can’t always agree on which screenings are necessary, with practices varying by region of the country and sometimes even within a single state’s boarders.

Investigators found, for instance, big variations in the percentages of patients screened for colon cancer in the states of Massachusetts, Minnesota, and Wisconsin. In Massachusetts, the lowest group rate for colon-cancer screening was 47 percent while the highest was just about double that figure (95 percent).  

Overall, the magazine’s review found tests for cervical, colon, and breast cancers are the most effective tests available, but screenings for bladder, lung, oral, ovarian, prostate, pancreatic, skin, and testicular cancers are a waste of time and money for most people.

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Among the findings and recommendations of the review:

• Cervical cancer — yes. Pap smears (analysis of cervical tissues) and a human papillomavirus test, which looks for the virus that can cause the cancer, earned CR’s highest score for women 21-65 years of age. Younger women should skip testing because the cancer is uncommon before then and screenings are not accurate for this age group. 
• Colon cancer — yes. Tests for colon cancer — colonoscopy (every 10 years), sigmoidoscopy (every five), plus a stool test (every three) — received top grades for people 50-75, but are less beneficial for seniors over 76 years of age. Colon screening received low scores for those 86 and older and under 50. Younger people should get testing only if they are at high risk because the cancer is uncommon before age 50.
• Breast cancer — yes. Mammography X-rays of the breast every two years garnered high grades for women 50-74, but those younger than 50 or 75 and older should talk with their doctor to see whether the benefits outweigh the harm based on their risk factors.
• Ovarian cancer — no. Two ovarian cancer tests — a transvaginal ultrasound or the CA-125 blood test for a protein linked with the cancer — were rated low for all women who are not at high risk because they don’t detect the disease at a curable stage.  
• Pancreatic cancer — no. Genetic screening and imaging tests of the abdomen to check for pancreatic cancer received CR’s lowest rating for adults who are not at high risk for the disease, because no test is likely to detect it at a curable stage.
• Testicular cancer — no. A physical exam by a healthcare specialist for testicular cancer is not recommended because most men don’t need it unless they are at high risk and most cancers found without screening are curable. 
• Bladder cancer — no. Checking for blood or cancer cells in urine to flag bladder cancer doesn’t help most people who are not at risk, Such tests are ineffective and most cancers found without screening are curable.     
• Lung cancer — no. Tests for lung cancer — involving a low-dose CT scan — are useless for most people who are not at risk because they are not very effective and the disease is very uncommon in non-smokers.
• Skin cancer — no. A visual skin exam for signs of melanoma, the deadliest form of skin cancer, is not necessary for adults who are not at high risk and is not effective. But individuals should see a doctor for suspicious changes in color, size, shape, or number of moles, particularly if they have a family history of melanoma, frequent sunburns, or are fair-skinned or heavily freckled.
• Oral cancer — no. Checking the mouth, usually by a dentist or healthcare provider, isn’t beneficial for most people who aren’t at risk, because oral cancer is uncommon in non-smokers and those who don’t have particular conditions that raise their vulnerability.
•  Prostate cancer — no. Use of the prostate-specific antigen (PSA) blood test isn’t recommended for most men who aren’t at risk of developing the disease. Men 50-74 years of age should talk with a doctor to see whether the benefits of the test outweigh the harm. Older men rarely need the test because the cancer typically progresses so slowly that treatment does not improve survival; younger men should consider testing only if they are at high risk, because the cancer is uncommon before age 50. Elevated PSA findings can lead to unnecessary biopsies and raise anxiety levels.

CR investigators recommend that patients ask their doctors several key questions before undergoing any cancer screening: If the test results are positive, will it save my life? Am I at higher risk for cancer than the average person, and if so, why? How often does the screening provide falsely reassuring results?  Are any other tests as good? If the results are positive, what’s next?

They added that cancer screenings aren’t the only way to reduce your risks from cancer by detecting it early. Making key lifestyle changes — getting regular exercise, eating a healthy diet, and avoiding unhealthy habits such as smoking — can help you avoid cancer in the first place.

“The medical and public-health community has systematically exaggerated the benefits of screening for years and downplayed the harms,” added H. Gilbert Welch, M.D., a professor of medicine at the Dartmouth Institute for Health Policy and Clinical Practice in Lebanon, N.H.

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In an article in the New England Journal of Medicine, Welch and colleagues found the number of early breast-cancer cases has soared since mammography became common three decades ago but advanced cancer cases hadn’t declined much. They estimated that in 2008 more than 70,000 women 40 and older were found to have small, nonaggressive cancers that were treated even though they probably wouldn’t be life-threatening. Such treatment, including radiation or surgery, can cause serious complications, such as bone loss and menopause-like symptoms. Screening can also lead to unnecessary biopsies, which can cause anxiety, and pose a small risk of infection.

“When it comes to screening, most people see only the positives,” said Otis Brawley, M.D., chief medical officer of the American Cancer Society. “They don’t just underestimate the negatives, they don’t even know they exist.”