Six screening tests for adults: What’s recommended? What’s controversial?
ABSTRACTThis paper discusses guidelines from the US Preventive Services Task Force (USPSTF) and other recommending bodies for screening for abdominal aortic aneurysm and cancers of the colon, cervix, lung, breast, and prostate.
KEY POINTS
- The USPSTF has stringent standards of evidence and therefore its recommendations tend to be more conservative than those of other organizations that issue guidelines. Recommendations are available at www.uspreventiveservicestaskforce.org.
- Because screening can result in harm as well as benefit, screening should be done after shared decision-making with the patient, especially if the screening is controversial, as is the case with mammography for breast cancer and prostate-specific antigen testing for prostate cancer.
- Screening for lung cancer using low-dose computed tomography is recommended yearly beginning at age 55 for people who have at least a 30-pack-year smoking history.
- In women over age 30, cervical cancer screening with Papanicolaou (Pap) and human papillomavirus (HPV) testing is now recommended every 5 years rather than every 3 years. Testing for HPV infection may soon become the first-line screening test, with Pap testing reserved for patients who have a positive HPV result.
- Although the USPSTF no longer recommends mammography for women ages 40 to 49, other organizations continue to do so.
CERVICAL CANCER SCREENING: MOVING TOWARD HPV TESTING FIRST?
Cervical cancer screening recommendations are fairly uniform across the major guideline-setting organizations.7 In general, they are:
- Ages 21–29: Check cytology every 3 years
- Ages 30–65: Cytology plus human papillomavirus (HPV) testing every 5 years (or cytology alone every 3 years)
- After age 65: Stop screening if prior screenings have been adequate and negative over the past 20 years.
Women who have been vaccinated against HPV have the same screening recommendations as above. Women who have had a hysterectomy for benign reasons do not need further screening.
The future of cervical cancer screening may be “reflex testing.” Rather than checking cervical samples for cytologic study (Papanicolaou smear) and HPV status together, we may one day screen samples first for HPV and, if that is positive, follow up with cytologic study. Easy-to-use home tests for HPV will likely be developed and should increase screening rates.
PROSTATE CANCER SCREENING: A SHARED DECISION
Prostate cancer screening remains controversial. Different guideline-setting bodies have different recommendations, creating confusion for patients. Physicians must follow what fits their own practice and beliefs.
The USPSTF in 2012 gave a grade-D recommendation to prostate-specific antigen (PSA) testing to screen for prostate cancer, stating that it did more harm than good. However, some men continue to be screened for PSA.
The American Cancer Society in 2013 recommended against routine testing for prostate cancer without a full discussion between physician and patient of the pros and cons of testing.8 If screening is decided upon, it should be done with annual PSA measurement or digital rectal examination, or both, starting at age 50. Men at high risk (ie, African American men, and men with a first-degree relative diagnosed with prostate cancer before age 65) should begin screening at age 45.
The American College of Physicians in 2013 issued a statement that clinicians should inform men between the ages of 50 and 69 about the limited potential benefits and substantial harms of prostate cancer screening.9 They recommended against PSA screening in men of average risk who are younger than age 50 or older than age 69, or those whose life expectancy is less than 10 to 15 years.
The American Urological Association in 2013 advised that10:
- PSA screening is not recommended in men younger than 40.
- Routine screening is not recommended in men between ages 40 and 54 at average risk.
- In men ages 55 to 69, decisions about PSA screening should be shared and based on each patient’s values and preferences. The decision to undergo PSA screening involves weighing the benefits of preventing death from prostate cancer in 1 man for every 1,000 men screened over a decade against the known potential harms associated with screening and treatment.
- To reduce the harm of screening, a routine interval of 2 years may be chosen over annual screening; such a schedule may preserve most benefits and reduce overdiagnosis and false-positive results.
- Routine PSA screening is not recommended in men ages 70 and older or with less than a 10- to 15-year life expectancy.
Shared decision-making. Many of the guidelines for prostate cancer screening are based on the concept of shared decision-making. However, studies indicate that many patients do not receive a full discussion of the issue,11 and in any event, patient education may make little difference in PSA testing rates.12,13
On the horizon for prostate cancer screening is the hope of finding a more predictable test. There is also discussion of using the PSA test earlier: some evidence shows that a very low result at age 45 predicts a less than 1% chance of developing metastatic prostate cancer by age 75, so it is possible that screening could stop in that population.
BREAST CANCER SCREENING: DIVERGENT RECOMMENDATIONS
The USPSTF created considerable controversy a few years ago when it recommended screening mammography from ages 50 to 74, and then only every 2 years—a departure from the traditional practice of starting screening at age 40. Few doctors heed the USPSTF guideline: most of the other guideline-setting organizations (eg, the American Cancer Society, the American Congress of Obstetricians and Gynecologists) recommend annual mammography for women starting at age 40.
Overdiagnosis is an especially pertinent issue with screening mammography for breast cancer because some cancers are indolent and will not cause a problem during a lifetime. Falk et al14 analyzed a Norwegian breast cancer screening program and found that overdiagnosis occurred in 10% to 20% of cases. Welch and Passow15 quantified the benefits and harms of screening mammography in 50-year-old women in the United States and found that of 1,000 women screened annually for a decade, 0.3 to 3.2 will avoid a breast cancer death, 490 to 670 will have at least one false alarm, and 3 to 14 will be overdiagnosed and treated needlessly.
Mammography screening for breast cancer will likely stay controversial for some time as we await additional data.
OTHER CANCERS: SCREENING NOT RECOMMENDED
The USPSTF currently does not recommend screening for ovarian cancer (guideline issued in 2012), pancreatic cancer (2004), or testicular cancer (2011), giving each a grade-D recommendation, indicating that screening does more harm than good. It also stated that there is insufficient evidence to recommend screening for oral cancer (2013), skin cancer (2009), and bladder cancer (2011).
