What do doctors need to know about prostate cancer and the tests used to diagnose it?
According to the American Cancer Society, who offer the most recent data regarding cancer statistics in the U.S., an estimated 161,360 men were newly diagnosed with prostate cancer in 2017. In the same time period, over 26,000 men died from the disease. A man’s risk of developing prostate cancer at any point during his life is 11.6 percent, and it is estimated that over three million men in the U.S. are currently living with prostate cancer. Despite the frightening large number of cases, statistical analysis shows the number of newly diagnosed cases has fallen an average of 5.8 percent per year over the last decade. Additionally, death rates have been falling an average of 3.4 percent annually.
When considering all stages, the most recent data reveals that the 5-year relative survival rate is 99 percent while the 10-year and 15-year rates are 98 percent and 96 percent, respectively. The relative survival rate is most accurate for predicting how the cancer affects survival – basically, it estimates survival among men with prostate cancer to that of the general population – however, if you look at stages of prostate cancer the rates are different. For example, Stage IVB cancer has a 5-year relative survival rate of only 29 percent.
Although survival rates are good, prostate cancer is perhaps the one malignancy most entangled in controversies: there are debates surrounding tests used to screen for and diagnose it, and then there are differences of opinion regarding its treatment. When the experts are in discord, imagine what patients face when trying to make informed decisions about their medical care for this cancer.
Perhaps the biggest controversy surrounding prostate cancer is the screening itself. The most well-known test used for screening is the PSA (prostate specific antigen). The PSA is a blood test that measures circulating levels of this antigen, which is released into the blood stream when cancer disrupts prostate cells. High PSA levels can raise suspicion of prostate cancer and detect it at earlier stages, thereby improving relative survival rates – but PSA can be elevated without cancer. An enlarged prostate (BPH=benign prostatic enlargement) or an infection of the prostate gland can cause elevated PSA levels, along with aging, urinary tract infections, strenuous biking and recent ejaculation. If the blood is not drawn before the digital rectal exam (DRE), some argue that could also potentially raise levels (although experts are still not in agreement on this).
In the U.S., the USPSTF (United States Preventative Services Task Force) creates the most commonly used set of cancer screening guidelines that physicians use in practice. Their most recent recommendation is:
“The draft recommendation encourages providers to inform men ages 55 to 69 about the benefits and harms of prostate cancer screening. That way, patients can work with their providers to make a decision about screening that’s right for them.”
Basically, when it comes to prostate cancer tests, doctors are left with inconclusive guidelines to discuss with their patients – then those patients are left to make an “informed” decision regarding PSA screening. When experts and physicians are lacking conclusive evidence that these tests are beneficial, it seems dubious that a patient could ever make a truly “informed” choice.
PSA Velocity Screening
PSA velocity (or measuring the rate of changes in PSA levels over time) is another screening test for prostate cancer that is very open to interpretation. The National Comprehensive Cancer Network (NCCN) and the American Urology Association (AUA) advise that men with a PSA velocity exceeding 0.35 ng/ml/year should have a needle biopsy, even if their PSA levels are normal and they have normal findings on DRE, while researchers at Memorial Sloan-Kettering Cancer Center and a study in the National Cancer Institute recommend against that course of action, as they argue PSA velocity does not provide any predictive accuracy nor improve clinical outcomes. Other experts also offer divergent recommendations:
- American Academy of Family Physicians (AAFP): “Evidence is insufficient to recommend for or against PSA or DRE screening”
- American Cancer Society (ACS): “Offer DRE and PSA screening annually to all men 50 years and older with a life expectancy of at least 10 years; men at high risk (e.g., black men, men with one or more first-degree relatives with prostate cancer before 65 years of age) should be screened starting at 45 years of age”
- American Urological Association (AUA): “Offer DRE and PSA screening annually to all men 50 years and older with a life expectancy of at least 10 years”
- USPSTF: “Evidence is insufficient to recommend for or against routine PSA or DRE screening; screening is unlikely to benefit men older than 75 years of age”
Since prostate cancer is a relatively slow growing cancer, many question the need for screening or treatment in the first place: several studies have shown unneeded biopsies are performed because of PSA screening, and many claim this drives up costs, increases rates of complications, and causes anxiety in the men affected. On the opposite side of the debate are those who point out that we cannot accurately predict whether a cancer will be a slow growing or aggressive type in specific people, and men with aggressive cancer types are being condemned to die by not performing biopsies.
Advances in Prostate Cancer Tests
Today’s reality is that doing a biopsy and not doing a biopsy both present risks: it is clear that we need better diagnostic tools for prostate cancer, and thankfully that work is already underway. One interesting study currently being conducted is the PRECISE study, which is trying to figure out if an MRI can be used to distinguish more aggressive cancer forms from more slow-moving ones. Initial data suggests that it may prevent approximately 250,000 men from undergoing unnecessary biopsies. PET scanning is also being investigating as a potential way to detect whether an individual’s cancer is likely to spread. As with many other diseases, genetic testing is also being studied.
Where Doctors & Patients Are Today
While the results of current research look promising, doctors on the frontlines are still left with conflicting diagnostic and treatment recommendations. We try to make the best of the available science, but in the meantime, we also bear the brunt of the blame for consequences – especially the cost incurred by our patients for tests that a significant portion of the scientific community believe should not be done.
Who, or what, determines whether a test is necessary or not? If a test is done and the results show cancer, it was clearly needed. If a test is done and it rules out cancer, it was ultimately not needed to begin a course of treatment for prostate cancer – but isn’t a negative outcome also valuable information that informs our care of patients? Until we can better tell which cancers are likely to behave in which ways, we can only practice the standard of care as it now exists. I see patients struggling with these questions regularly and at this point, I believe the cost of doing a biopsy (financial, emotional and otherwise) is still probably worth it – what do you think?
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About the Author
Linda Girgis MD, FAAFP is a family physician practicing in South River, New Jersey and Clinical Assistant Professor at Rutgers Robert Wood Johnson Medical School. She was voted one of the top 5 healthcare bloggers in 2016. Follow her on twitter @DrLindaMD.