Large clinical trials change experts’ minds on prostate cancer screening

Prostate cancer screening is now something to consider for men aged 55 to 69, according to the federal panel tasked with making recommendations for such preventative care options. In a finalized recommendation released Tuesday, the US Preventive Services Task Force (USPSTF) revealed that it has officially warmed to the screening—ever so slightly.

Back in 2012, the task force famously recommended against the then-common blood screening for elevated levels of PSA protein, which can indicate prostate cancer as well as other conditions. But, given new data from large, randomized clinical trials showing that routine screening can save a small number of lives, the USPSTF now says the scales have tipped in screening’s favor.

The USPSTF doesn’t offer an emphatic endorsement, but rather, a cautious consideration:

“For men aged 55 to 69 years, the decision to undergo periodic prostate-specific antigen (PSA)–based screening for prostate cancer should be an individual one. Before deciding whether to be screened, men should have an opportunity to discuss the potential benefits and harms of screening with their clinician and to incorporate their values and preferences in the decision.”

The task force still has the same recommendation for men aged 70 and over, which is against screening. The benefits still don’t outweigh the risks for this age group, the panel says.

These latest recommendations are mostly in line with those of the American Urological Association, American College of Physicians, and the American Cancer Society, all of which stress informed, individual decision-making with the patient. The latter two organizations say men should consider the screening at 50, not 55, however. The American Academy of Family Physicians and the Canadian Task Force on Preventive Health Care, on the other hand, continue to recommend against screening.

Still, while no organization offers a resounding endorsement, and some advise against screening, the USPSTF’s earlier recommendation was considered “controversial” at the time. The USPSTF has a knack for getting this label. This may be due in part to how it comes up with its recommendations. While some doctors and health experts may tend to focus on screening benefits and overall public health gains—i.e., the chance to catch a rare or unexpected cancer and the chance to save some number of lives over time, however small—the USPSTF carefully weighs evidence based on quality and the patient's individual benefits and harms, even taking into consideration intangible harms, such as stress and anxiety from false-positive test results. It also doesn’t factor in costs. This includes the costs of an individual screening and may also extend to long-term costs such as how much individuals or healthcare systems overall might pay for future disease treatments—with or without screenings.

A bum rap

For prostate cancer screening, the USPSTF focused on the benefits and harms of screening and treatment. Prostate cancer is one of the most common types of cancers affecting men. In the US, the lifetime risk of getting a diagnosis is 13 percent, and the risk of dying from the disease is 2.5 percent. In 2013, approximately 172,000 US men were diagnosed, and almost 28,000 died.

Elevated PSA levels in the blood are most often used to catch the cancer early, but this screening can also pick up the benign condition of an enlarged prostate and inflammation. One trial found that men screened every two to four years for a 10-year period had a 15-percent chance of getting a false positive result. This can cause stress, anxiety, and lead to unnecessary diagnostic tests and biopsies, which come with their own set of harms and risks, including infection and pain.

A diagnosis may also pick up slow-developing prostate cancers that may otherwise have never been symptomatic or posed a danger to health—aka, “overdiagnosis.” Follow-up from one large trial suggested that overdiagnosis was the case for 20 percent to 50 percent of the men diagnosed through routine screening. And treatments for prostate cancer, such as prostate removal and radiation therapy, have significant and common potential harms, such as long-term erectile dysfunction, urinary incontinence, and bothersome bowel symptoms. Even the more conservative “active surveillance” strategy for treatment—a sort of wait-and-see approach—comes with the anxiety and stress from sustained vigilance and repeated exams and screenings.

For these reasons (and others), the USPSTF recommended against routine screening in the past. But a new set of large clinical trials, including two in Europe, have highlighted the benefits of the screening. They suggested that for men aged 55 to 69 years, screening may avert about 1.3 deaths from prostate cancer over roughly 13 years per 1,000 men screened. The screening may also prevent about three cases of metastatic prostate cancer per 1,000 men screened.

This was enough to sway the USPSTF for the 55 to 69 age group. It assessed the quality of the data overall as “moderate” and upgraded its recommendation from a “D” (recommend against) to a “C” (provide screening for select patients based on individual circumstances.)

But, the new recommendations and existing data still leave a lot of unanswered questions. For instance, it’s still not clear what screening intervals might be best and for whom—every two or four years? More frequently for African-Americans or people with a family history, both of which have higher risks of prostate cancer? There’s simply not enough data to make good or clear calls on these specifics yet.

JAMA, 2018. DOI: 10.1001/jama.2018.3710  (About DOIs).