“Cancer screening should be a regular part of your life,” states the American Cancer Society (ACS). When it comes to screening tests (e.g., Pap smear, mammogram, colonoscopy, PSA blood tests, etc.) there are two kinds of people: those who wholeheartedly embrace ACS’s advice, and those who don’t.
Those in the first group believe that not taking any chances with cancer outweighs the inconvenience, discomfort, and cost of screening tests. Put simply, they fear cancer more than they fear testing for it. On the other hand, those in the second group believe the statistical unlikelihood of getting cancer outweighs the troubling aspects of many screening tests, including false positives, more tests, test side effects, and overtreatment. For them, screening just isn’t worth it.
When it comes to broad PSA screening for prostate cancer (PCa), the US Preventive Services Task Force is in the second group. They are not in favor of it because the PSA blood test is not specific for PCa. It only indicates that something is stimulating the gland, be it an infection, BPH, sexual activity, or cancer. Even pressure from an external source like a bicycle seat or doctor’s gloved finger can cause the level of PSA in the blood to rise. Thus, a suspicious PSA too often leads to an invasive needle biopsy. In turn, biopsies too often lead to overtreatment of insignificant PCa and resulting urinary, sexual or bowel side effects. As on researcher recently pointed out, detecting a harmless tumor has been “the biggest obstacle to introducing general screening for prostate cancer.”[i]
To put screening in perspective, there is no single type of cancer screening test that is 100% accurate. Taksler, et al. (2019) write,
False-positive cancer screening test results are common. Over 10 years, approximately 50–61% of women undergoing annual mammography and 10–12% of men undergoing regular PSA testing will experience a false-positive result. Similarly, 23% of individuals undergoing regular fecal occult blood testing will experience a positive result with negative follow-up colonoscopy. Efforts to reduce false-positives are cited in support of biennial (vs. annual) mammography, while overdiagnosis—which might be considered a false-positive because patients are treated unnecessarily—is cited in recommendations against routine prostate cancer screening…[ii]
What if screening for PCa were more tailored, more specific for cancer, so men would not have to endure the anxiety of a false positive and the subsequent domino effect of biopsy and overtreatment? A solution is brought forward by Hugosson, et al. (2022).[iii] It’s essentially a second layer of selective screening following a suspicious PSA result. As the authors wrote, “We must get away from the blind sampling of tissues that’s still standard today, rely on the MRI examination, and thus switch diagnostics to taking samples only in those men in whom MRI has depicted tumors — and then only do targeted samples in the area involved.” Thus, MRI functions as a filter after a suspicious PSA. With its ability to distinguish normal tissue, insignificant PCa, and significant PCa, it can determine which men should undergo biopsy—and only an MRI-targeted biopsy requiring minimal needles.
The authors tested this protocol by means of a very large comparison study. 17,980 men had PSA screening tests. Anyone whose PSA was equal to or greater than 3 ng/mL had an MRI prostate scan. 5994 were assigned to a “reference group”; if their MRI was revealed any suspicious lesions, they had a systematic biopsy as well as MRI-targeted biopsy. 11,986 were assigned to an “experimental” group, who had MRI-targeted biopsy ONLY for any suspicious lesions.
The results showed that the risk of finding insignificant PCa (does not need immediate treatment) in the experimental group was half of that in the reference group, while findings of significant PCa were roughly equivalent in both groups. To put it another way, the group that received both systematic plus targeted biopsies were found to have twice as much insignificant disease as the targeted-only group. And it is the diagnosis and overtreatment of insignificant disease that is the problem, and the excuse for not conducting broad PSA screening.
To sum up, using MRI scans to further clarify suspicious PSA results can identify which patients need a biopsy, and an MRI-targeted biopsy is sufficient to determine if significant PCa is present. Therefore, men who don’t need a biopsy can avoid it, and men who don’t need immediate treatment can avoid overtreatment. Thankfully, this cuts the rate of overdiagnosis and over treatment in half.
Solving the to-screen-or-not-to-screen dilemma would restore patients’ and physicians’ trust in the relatively cheap and easy PSA blood test. Men no longer have to fear that an abnormally high PSA result is a “Go Directly to Biopsy” roll of the dice. The alternative protocol of MRI before biopsy reveals the true situation, allowing the next steps to be the right ones for each person.
NOTE: This content is solely for purposes of information and does not substitute for diagnostic or medical advice. Talk to your doctor if you are experiencing pelvic pain, or have any other health concerns or questions of a personal medical nature.
[i] Kate Madden Yee. “MRI-targeted biopsy protocol halves overdiagnosis.” AuntMinnie.com. Dec. 8, 2022. https://www.auntminnie.com/index.aspx?sec=sup&sub=mri&pag=dis&ItemID=138897
[ii] Taksler GB, Keating NL, Rothberg MB. Implications of false-positive results for future cancer screenings. Cancer. 2018 Jun 1;124(11):2390-2398.
[iii] Hugosson J, Månsson M, Wallström J, Axcrona U et al. Prostate Cancer Screening with PSA and MRI Followed by Targeted Biopsy Only. N Engl J Med. 2022 Dec 8;387(23):2126-2137.