Prostate Cancer Statistics: Anything You Want Them To Be—Commentary
A recent study in Prostate Cancer and Prostatic Diseases from Northwestern University and the University of Chicago suggested that after many years of improving survival, the number of cases of metastatic prostate cancer was on the rise. The researchers reviewed data from 2004 to 2013 in the National Cancer Database, a repository of data from over 1000 US hospitals, and concluded that there was an increase of 7% per year in metastatic prostate cancer over the last few years. The conclusion strongly intimated that the recommendations of the U.S. Preventive Services Task Force (USPSTF) not to screen for prostate cancer were at least in part the cause of this increase. Others, including a medical director from the American Cancer Society, entered the conversation in newspaper interviews and said that the data presented did not allow anyone to conclude that metastatic prostate cancer is on the rise. But, just a few weeks later, epidemiologists from the American Cancer Society published another paper that suggested a “disturbing trend” that early stage prostate cancer diagnosis was decreasing likely due to less PSA based screening over the last few years.
Prostate cancer is the leading solid tumor in men and the second leading cause of death in American males. Its prominence, however, has made prostate cancer one of the most controversial diseases. As a common cancer in older men, the costs of screening and treatment can be enormous. With an average age at diagnosis of around 68 years, most men diagnosed with prostate cancer are thus Medicare beneficiaries with the government covering the cost of a large proportion of men. A peculiarity of prostate cancer is the concept of over diagnosis and overtreatment due to the fact that if a man lives long enough he will develop histologic diagnosis of prostate cancer. Over 70% of men 70 to 79 years of age will harbor prostate cancer. Most older men will die “with” prostate cancer rather than “of” prostate cancer. Many men diagnosed and treated for this disease would never have known or suffered any consequences of these so called “autopsy cancers”.
Another classic example of the controversies that surround prostate cancer are the two simultaneously released 2009 publications on two prospective randomized prostate cancer screening trials. The US based PLCO (Prostate, Lung, Colorectal, and Ovarian) Cancer Screening Trial study of 76,000 men failed to demonstrate a reduction in prostate cancer deaths with screening. However, the ERSPC (European Randomized Study of Screening for Prostate Cancer) based in Europe demonstrated a 20% reduction in prostate cancer death in a group of 182,000 participants. If you wanted to believe in prostate cancer screening, you adopted the ERSPC paper. If you were against screening, you became a fan of the PLCO study. However, as time has gone on, the ERSPC trial screening group continued to show improved outcomes with further long term follow up. . Alas, the PLCO has been hit with widespread criticism since further analysis demonstrated that the majority of men in the “non-screened” control arm in fact had PSA testing at their community health fairs or had the testing done by their primary care providers. The control arm was essentially non-existent for the prostate cancer population of the PLCO study.
The controversial USPSTF recommendation not to screen for prostate cancer was circulated for comment in 2011 and officially published in 2012. The group relied heavily on the PLCO data that was cited as central reason for the original USPSTF “do not screen” recommendation. That final “D” recommendation is currently being reevaluated by the USPSTF. These anti prostate cancer screening guidelines have been widely adopted by primary care providers who have reduced their efforts to detect prostate cancer through PSA based screening. The “Choosing Wisely” campaign led primarily by the American College of Physicians has also influenced patients and providers alike to limit PSA based prostate cancer screening. Other groups such as the American Cancer Society, American Urologic Association and others believe in shared decision making.
Whether these decreases in screening will lead to increases in death due to prostate cancer in the coming years remains to be determined. With prostate cancer’s slow growth characteristics, the impact (good or bad) of any change in screening or treatment takes years to demonstrate.
What cannot be debated is the dramatic progress in survival, with prostate cancer death rate falling on average 3.5% each year from 2004 through 2013. The five year survival now approaches 99%. While the use of PSA screening has been credited by many authorities to these historic survival improvements, advances in the treatment of localized and advanced disease have also contributed.
Going forward, research into optimizing prostate cancer diagnosis and treatment will continue—and the debate over these controversies will also persist. New biopsy techniques such as MRI fusion biopsy, molecular and genomic studies that more accurately risk-stratify men and predict the behavior of a man’s prostate cancer, and the increase in active surveillance are successfully addressing many of these challenges. Realistic assessment of all this prostate cancer data must continue to be debated in academic and public forums. Ultimately all of these data that are subject to interpretation must be individualized in the real world of patient care.