By Dr Robin Roberts, Urology Consultant, Director
UWI School of Clinical Medicine & Research, The Bahamas
Dr Roberts continues the discussion on the controversial recommendation by the US Preventative Services Task Force (USPTF) for patients to stop taking the routine prostate specific antigen (PSA) exam, which looks for signs of prostate cancer.
So why has PSA testing become such a controversial issue?
The initial use of PSA was to determine the recurrence of prostate cancer after the cancer has been treated. This use of the PSA test remains without question.
PSA is extremely accurate in detecting if and when the prostate cancer recurs. PSA can detect the recurrence of the cancer in very small or microscopic amounts, months to years before the cancer reveals itself at detectable levels by X-rays or before the person experiences symptoms or signs of the cancer reappearance.
When PSA was discovered initially, it was used purely for this purpose. The use of PSA for detecting the first presence of prostate cancer, i.e. in diagnosing it, is where and when the controversy began.
The logic for a wider use of PSA test was quite simple: PSA was great for detecting very small and early recurrences - why not use it for diagnosing the cancer from the earliest onset. The cancer would be detected early before it spreads outside the prostate, destroyed completely and the patient would be cured. In this way, prostate cancer detection and treatment planning was identical to breast and cervical cancers in females - the PSA test being equivalent to the mammogram or the PAP test.
So why the PSA test controversy? The spotlight is on screening: It is imperative to understand "screening" in the context of diagnosing a cancer. A screening program is introduced to detect a disease that is very common, producing significant suffering (or morbidity) and is a major cause of death (or mortality) in a community. The assumption is that if the condition is detected early, it can be treated effectively to reduce suffering and its cancer related deaths. Screening is the process whereby the health care providers reach out into the community, summon and test the healthy residents (i.e. without symptoms), with the intent to detect the early occurrence of the cancer and thus treat and eradicate the cancer in this early stage. In a successful screening program, less people will die because the cancer is detected early and treated effectively. (Despite the same outcome, technically screening is quite different from the individual who seeks to have his prostate test during his annual physical examination. One presumes that the individual is healthy at this office visit for the annual routine physical examination. PSA testing on this occasion would be termed an early detection test; the term screening should be reserved for testing a population of people at one time.)
The Task Force based its recommendations on the results of two large clinical research studies reported in 2009. The United States PLCO (Prostate, Lung, Colon and Ovarian) Cancer Screening Trial which assigned randomly 76,685 men ages 55 to 74 years into two groups, one to receive annual screening for 6 years and the other the "usual care", i.e. no routine PSA testing. The ERSPC (European Randomized Study of Screening for Prostate Cancer) similarly assigned randomly 162,243 men aged 55 to 69 years into two groups, one to receive PSA screening once every 4 years and the other to an un-screened control group. The Task Force reviewed the results of these two major screening programs on the healthy males and made their conclusions. The American study showed that the group that was screened and tested regularly, showed no decrease in the death rates when compared to the "usual care" group that had no regular screening or PSA testing. In the European screening program there was evidence confirming a reduction in death rates of the group that had regular PSA testing, but the Task Force was not satisfied that the difference was large enough.
The Task Force had great concerns on several other issues emanating from PSA testing:
Treatment complications: Those who were proven to have prostate cancer and were treated, incurred complications that impacted significantly and adversely on the man's quality of life. If they had surgery to treat the cancer, 29 out every 1000 were sexually impotent afterwards, 18 of every 1000 were incontinent of urine and 1 of 3000 died. Those who had the alternative treatment, i.e. radiation, had complications noted as well.
Undue psychological stress: An elevated PSA is not conclusive for prostate cancer. Any prostate disease or disorder can cause an elevated PSA. If the PSA test is elevated, the man must have a prostate biopsy to determine if it is due to prostate cancer or to some other non-cancerous prostate condition. About 10% of men screened will have an elevated PSA and overall about 2% of them will be proven positive for the cancer. The Task Force determined that the men with a negative biopsy, thus false positive for prostate cancer, suffer significant psychological trauma awaiting the result of the biopsy.
Biopsy complications: Men are also at risk for complications of the biopsy such as discomfort, infections and bleeding.
Unnecessary treatment: The biology of prostate cancer growth still eludes physicians and researchers. While some prostate cancers result in death due to their rapid uncontrolled growth, many cancers are very slow growing, in fact, never progress at all. Most men die with prostate cancer rather than because of it. Those against PSA testing suggest that the cancer is detected too early, and would have never grown to cause any cancer problems or death. If left alone, these men would never have succumbed to the complications of a biopsy, or worst still, the treatment.
The opponents targeted every facet of the Task Force's recommendations.
The Task Force is predominantly a group of family medicine physicians with expertise in preventive medicine and screening. There are no urologists or cancer specialists in their membership. It is of interest to note that this is the same entity that issued a statement against mammography screening several years ago; the statement was challenged and was subsequently withdrawn.
Prostate cancer experts have expressed their strong opinions that the Task Force conclusions were based on flaws in the methods in the two trials. In the PLCO trial, more than 50% of the men who were not to have been screened (the control group), were screened before. The study was contaminated; comparing men who were partly screened out already with those were being screened. Moreover, two thirds of those with abnormal screening tests did not have prompt biopsy. Those who oppose the Task Force's recommendations, concluded that the PLCO trial was not a true trial.
In the European trial, there was very little contamination and the men were biopsied more frequently. More importantly when they concentrated on one subset that actually stuck to screening protocols and were biopsied on time, PSA screening reduced the risk for dying of prostate cancer by as much as 31%.
- It is commonly stated that most men diagnosed with prostate cancer die with it, not because of it. This does not negate the fact that many men do die because of it. In the Bahamas, one prostate cancer victim dies every two weeks; an estimated 32,000 die per year in the United States and 250,000 people worldwide.
Prostate cancer is slow growing, at least in its initial stages. What triggers the rapid growth phase is yet to be determined. (Genetically, hereditary transmission and African ancestry have been identified; environmentally, only a high fat diet intake has statistical significance.)
The Task Force recommendation opposes PSA testing regardless of age. While the expected life span for a man aged 75 years is approximately 10 years, it extends to 30 years for men at age 45 to 50 years. While it is plausible that many men aged 75 years or older will die of other causes before developing metastatic prostate cancer (because of its slow growth), one cannot or should not use this sweeping statement for men aged 40 to 50 years.
The Task Force ignores the evidence of PSA testing on saving lives: The evidence shows that since PSA testing, the death rates from prostate cancer have decreased by 40% over the past 10 plus years. There are also excellent studies showing that men who have been treated for early prostate cancer diagnosed initially by PSA testing and 15 years later almost 40 % of them have remained free of prostate cancer.
The Task Force ignores the evidence of PSA testing on decreasing pain and suffering from prostate cancer associated with advanced disease: Since the introduction of PSA testing, the number of men who present for the first time with metastatic prostate cancer has decreased by 75%. This is a universal phenomenon. While several studies suggest there are exceptions in certain populations where a decrease in the death rates has not occurred, the number of men presenting with advanced disease conditions has fallen definitely. The Task Force focused primarily on cancer deaths, failing to acknowledge that men who are not screened for prostate cancer are more likely to present with advanced disease with substantial illness and more likely to die from it.
The Task Force ignored the major financial implications of a "D" grade rating: The "D" rating is a red light for the insurance industry. Tests with a "D" rating are not required to be reimbursed. Third-party insurers have been given the green light not to pay. This could affect the health and lives of men at high risk for life-threatening disease. As noted by Dr. William Catalona, internationally renowned urologist, in his reply to the Task Force in the Annals of Internal Medicine Journal, We believe that elimination of re-imbursement for PSA testing would take us back to an era when prostate cancer was often discovered at advanced and incurable stages.
And it is a matter of cost: A "D" grade denotes that PSA testing is not recommended for healthy men. From a cost perspective, the insurance companies and governments that fund health care will have major savings. Prior studies in the USA as early as 1990, suggest that the estimated cost resulting from the first year of screening men 50 to 70 years was $27.9 billion using PSA testing, as opposed to 3.8 billion if only digital rectal examinations were used. Screening with PSA testing alone was projected to be 5% of the total US health care budget. Again, what great savings if PSA testing could be deemed unnecessary.
While the concerns of over-detection and over-treating prostate cancer and the potential complications of treatment are well recognized, like my urological colleagues and numerous prostate cancer advocacy and support groups, we believe that the benefits of early detection, the ability to project risk for prostate cancer, and the opportunity for successful treatment, far outweigh the shortcomings. The Task Force has taken a "don't ask, don't tell" sweeping approach for all ages, we must oppose this and not throw out the baby with the bath water.
While this article focused heavily on men of African origin, no Bahamian male, be he black or white should delude himself that Prostate cancer does not effect all groups. This cancer remains the leading cause of death for both black and white men alike, including Bahamians.
On behalf of the Cancer Society of the Bahamas, I continue to recommend and urge all Bahamian men between the ages of 40 to 70 years, to have their annual rectal digital examination and PSA blood test for the early detection of prostate cancer. The life you save from this cancer's painful illness and death, may be your own.