Posted by Bill Sandweg on 21 October 2019.
One in nine men will develop prostate cancer during their lifetimes. Most will die of something else. Fewer than 20% will develop the aggressive form of the cancer which is most likely to spread and to kill the patient. Until now, medicine has not had a reliable way of detecting prostate cancer and then distinguishing between low-level cancers and the aggressive ones likely to cause death.
The most common form of test for prostate cancer today is the PSA test. PSA (Prostate Specific Antigen) is a protein produced by the prostate. When prostate cancer is present, the prostate produces more PSA. An increase in a patient’s PSA levels may, therefore, indicate the presence of cancer. The problem, however, is that there are other, reasons why the prostate might produce higher levels of PSA, including infection, inflammation and benign enlargement of the prostate. A high PSA reading is what medicine calls a “non-specific finding,” that is, it may have many causes and is not necessarily indicative of the presence of disease.
In order to determine if a high PSA reading is the result of prostate cancer, doctors usually perform a biopsy of the prostate. In the biopsy, a needle is inserted into the prostate and some cells are removed and analyzed. Biopsies of the prostate are risky and may cause bleeding and infection. Even if they detect the presence of cancerous tumor cells, the cancer may be of the slow-growing kind that should not be the subject of aggressive treatment. Most urologists and oncologists agree that slow growing tumors should be carefully watched and aggressively treated only if they show signs of rapid progression.
Many men, however, upon being told they have prostate cancer are reluctant to accept a suggestion of “watchful waiting.” It may be because they fear any diagnosis of cancer. It may be because their families insist they “get something done.” Positive biopsies, therefore, often lead to one of the three main treatments for prostate cancer: (1) prostatectomy, in which the prostate is removed; (2) radiation therapy; or (3) brachytherapy, in which radioactive beads are placed in the prostate. While these treatments may be successful in controlling prostate cancer, each is likely to leave the patient both unable to get a functioning erection and incontinent of urine.
For all these reasons, it is widely recognized that the PSA test leads to overdiagnosis of prostate cancer and overtreatment. A better test is needed and one may be at hand.
A paper recently published in the Journal of Urology found that patients with aggressive forms of prostate cancer could be identified with over 90% accuracy by the presence of circulating tumor cells in the blood combined with elevated PSA scores and a positive 12 gene panel study. The new test will permit doctors to avoid unnecessary biopsies and treatments and concentrate their resources on prostate cancers which are truly aggressive. It will also save many men from impotence and incontinence.
Researchers expect the new test, which needs regulatory approval, to become widely available in the next three to five years.