28 May Prostate Cancer Controversy
Prostate Cancer Controversy
By Dr. Lannis Hall
Controversy and confusion regarding screening for prostate cancer have accelerated since the latest proposal from the U.S. Preventive Services Task Force was issued, recommending that healthy men, high-risk individuals (including African-Americans and men with a family history) not receive PSA screening for prostate cancer.
The task force concluded that there was little evidence establishing that PSA screening reduced mortality and that there are quality of life issues associated with treatment.
Prostate cancer is the most common non-skin malignancy diagnosed in men yearly, with approximately 238,500 diagnosed in 2013. It is the second leading cause of cancer death in men, preceded only by lung cancer with 29,700 deaths in 2010. One in six men will be diagnosed with prostate cancer and one in 36 will die of it.
African-American men have the highest incidence of prostate cancer and the highest mortality rate of any ethnic group. One in five African American men will be diagnosed and one out of 20 will die from the disease.
Prostate Specific Antigen (PSA) screening has been in routine use since the late 1980s and is responsible for the increased diagnosis and treatment of prostate cancer. PSA is an enzyme secreted by benign and malignant prostate tissue; thus, PSA is specific for the prostate gland and not prostate cancer.
Other, benign processes can cause an elevation in the PSA. This may lead to unnecessary biopsies, which were cited by the task force as a major reason for not recommending PSA screening.
However, most screening tools, such as screening mammography, have false positives, and there are several other tests available for physicians to determine if a PSA elevation is related to a benign or malignant process before proceeding to biopsy.
There have been five randomized controlled trials throughout North America and Europe assessing the value of PSA as a screening tool. Three of the trials were considered of poor quality.
The task force concentrated on the two remaining screening trials, the Prostate Lung Colorectal and Ovarian Cancer Study (PLCO) and the European Randomized Study of Prostate Cancer (ERSPC). These two studies produced conflicting results, with the PLCO study indicating no survival advantage for men who underwent PSA screening compared with men who underwent usual care. The major flaw of the PLCO study was that over 50 percent of men assigned to usual care had been screened by PSA.
The ERSPC recruited a total of 162,243 participants throughout the 1990s in seven western European countries. Men were assigned to PSA screening at an average of once every four years or to a control group that did not receive screening. Prostate cancer death was reduced by 20 percent in men screened with PSA as compared to the unscreened men 55-69 years of age.
Both of these studies indicate that thousands of men diagnosed with prostate cancer have a slow-growing disease that may not require treatment. These prostate cancers typically present with a low PSA and a small amount of slow-growing prostate cancer found at the time of biopsy.
PSA has increased the likelihood of finding prostate cancer, and it has become imperative that health care professionals explain the importance of active surveillance in low-risk prostate cancers. The concept of delayed treatment or no treatment is not new for oncologists. Other malignancies, such as slow-growing lymphomas, have been managed in this manner for years.
The conflicting results of the American and European studies and the concern for overtreatment of slow-growing prostate cancers have caused confusion for organizations attempting to provide screening recommendations.
The task force, unfortunately, recommends no screening during any man’s lifetime, regardless of prostate cancer being the second leading cause of cancer death in men and regardless of the obvious improvement in prostate cancer mortality rates in the past 20 years.
Surveillance Epidemiology and End Results (SEER) reports a five-year survival of 100 percent for men presenting with localized disease and five-year survival for 30 percent of men presenting with metastatic disease (prostate cancer that has spread to distant organs). The Center for Prostate Disease Research has reported that the percentage of men presenting with metastatic disease in the U.S. has declined from 19.8 percent in 1989 to 3.3 percent in 1998.
Prostate cancer death rates continue to fall at a rate of 4.1 percent per year annually. The improvement in survival directly parallels PSA screening and is attributable, in part, to diagnosis at an earlier stage. This decrease in mortality is greater than that seen annually in breast or colorectal carcinoma.
There is no debate among oncologists and urologists that prostate cancer is incurable when the disease has spread to distant organs. There is no other screening test to help identify the basic health of the prostate gland and alert health care providers to potential prostate issues.
The task force raises an additional concern by including African-American men and men with family history of prostate cancer in these new recommendations. The PSA screening studies have insignificant numbers of high-risk men to make a statistically valid assessment of the harms or benefits of screening this population.
Thus no special analysis has been presented on the effectiveness of screening high-risk men. This is particularly alarming when African-American men have an earlier onset of prostate cancer and a mortality rate that is 2.5 times greater than white men.
This task force just two years ago advised against mammography screenings in women age 40-49 years of age. There was a public outcry against that recommendation, stressing that mammography did indeed save lives and no woman wanted to be on the wrong side of a risk-benefit ratio.
Now we are being presented with a recommendation against screening in a man’s lifetime when there is no replacement-screening paradigm. Unfortunately, there are no early signs and symptoms for prostate cancer, so for many men there would be no fire alarm until the house is in flames.
Discussion with health care providers regarding the benefits and risks of screening for prostate cancer is essential. These discussions must be informed by statistics regarding the increased lethality of prostate cancer and the earlier onset of disease in African-American men and men with family history.
Prostate cancer can progress slowly or proceed with devastating lethality. Despite the limitations in PSA screening, it is the best tool currently available. Deciding to have a PSA test should remain an important option for every man. Knowledge is power.
Lannis Hall, MD MPH, is director of Radiation Oncology at the Alvin J. Siteman Cancer Center, Barnes St. Peters, and clinical trials leader in the Program to Eliminate Cancer Disparities at the Washington University School of Medicine.