For a newly-diagnosed prostate cancer patient, the three most important initial parameters are the blood levels of prostate-specific antigen (PSA) and its rate of increase, the biopsy-based Gleason score that ranks a tumor’s aggressiveness, and the clinical stage of the tumor based on its physical appearance. In the early 1990’s, Dr. Alan Partin, currently director of Urology at the Johns Hopkins Hospital in Baltimore, MD, formulated the Partin Tables using data comprised of the three parameters above as a statistical modeling tool to predict the stage of cancer spread at the time of performing a radical prostatectomy and to assess the chance of a surgical cure. These tables were based primarily on data from men treated in the 1980’s who often were diagnosed with later-stage cancers. The tables have recently been updated with data from over 5,000 men treated at Johns Hopkins between 20o6-2011 and published in the British Journal of Urology International. The revised study found that men treated during this period were more likely to be diagnosed before their PSA had risen significantly and were more likely to have a Gleason score greater than six (6) at the time of biopsy. According to Dr. Partin and his colleagues, the updated Partin Tables show that “surgical cure may be possible for a greater percentage of men especially those whose Gleason scores (such as 8) put them at the high end of intermediate risk.” The updated tables also found that the majority of men who are diagnosed prior to surgery with intermediate Gleason scores of 6 or 7 had a very low (less than 2%) risk of having prostate cancer spread to surrounding lymph nodes. These terms are defined and discussed in more detail in an article published in the January 2013 issue of NewsPulse from the Prostate Cancer Foundation.
The Johns Hopkins Prostate Disorders Health Alerts recently published (Feb. 14th, 2013) a short article defining the terms used in the TNM (tumor, nodes, metastasis) staging system used to define a cancer’s clinical stage or how far it has spread. The TNM prostate cancer staging system is a predictor of the extent of the disease and is useful in choosing the best course of treatment.
A related study describing the effects of exercise on prostate cancer survival was recently published in the Journal of ClinicalOncology and summarized in the January 24th issue of the Johns Hopkins Prostate Disorders Health Alerts. Data was received from 2,705 men followed for a period of 18 years. The study concluded that any type of regular exercise improved overall prostate cancer survival regardless of the intensity of the exercise. However, men who took part in vigorous activity, defined as at least three hours of intensive exercise per week, had a significantly lower (61%) risk of dying from prostate cancer.
Active Surveillance (AS) is a monitoring program with possible application for patients diagnosed with low-risk prostate cancer. It is gaining popularity as a means to avoid overtreatment of indolent, slow-growing prostate cancers. The likelihood of harboring small bits of prostate cancer in a man is about equal to his age as a percentage. For example, in men age 50-70 (the key age group for diagnosing prostate cancer), around 60 percent of men will have small bits of prostate cancer. An example of a good candidate for AS would be a man with a mildly elevated PSA (less than 10) whose biopsy shows a relatively small amount of Gleason 6 prostate cancer. During active surveillance, prostate cancer is carefully monitored for signs of progression using a PSA blood test, a digital rectal exam (DRE) and a repeat biopsy of the prostate at one year and then at specific intervals thereafter. Subsequent treatment might be initiated if symptoms develop, or if tests indicate the cancer is growing. Recently, multiparametric magnetic resonance imaging (MRI) has also emerged as a tool in monitoring patients on AS. A new retrospective study published in the Journal of Urology (and summarized in the Jan. 23, 2013 issue of the Prostate Cancer Foundation NewsPulse) looked at a group of 262 men who were placed on a program of active surveillance in order to determine the rate of disease progression and time frames the men remained on active surveillance before moving to active treatments such as surgery, radiation or cryotherapy. During the follow-up period (a median of 29 months), 16 percent of the patients in the study ultimately received active treatment for their cancers. The authors found that the two-year probability of the men to remain on active surveillance was 91 percent; at 5 years, 75 percent. This study “provides short-term evidence that for highly-select patients, AS appears to be safe, durable and associated with low but finite risk of disease progression.” Larger and longer-term studies are needed and on-going. In an important comment, study author Dr. Peter Scardino strongly urged for a “mandatory” restaging, or repeat biopsy prior to men enrolling in an AS program. The researchers base this on their finding that a repeat biopsy prior to the initiation of active surveillance deceased the percentage of men deemed to be low-risk by approximately 30 percent.
Another very interesting review article on AS has also been published in the Feb. 2013 issue of the Prostate Cancer Research Institute (PCRI) insights.One specific note from this article describes on-going research on the effects of capsaicin, the micro nutrient found in hot chili peppers. There is a specific receptor (TRPV-6) for capsaicin in prostate cancer cells which when activated results in inhibition of cell proliferation and invasion. Studies are on-going in mice and humans. The same review of active surveillance also describes a method of specifically killing prostate cancer cells in men using MRI-guided thermal ablation (targeted ultrasound waves which are converted to heat in the prostate tissue).
Finally, it should be noted that the terms “active surveillance” and “watchful waiting” differ as applied to prostate cancer. AS is a disease management strategy that delays curative treatment until it is warranted based on defined indicators of disease progression. In contrast, the strategy of “watchful waiting” foregoes curative treatment and initiates intervention only when symptoms arise.
I don’t usually write about the implications of diet on prostate cancer. But a former scientific colleague recently sent me an article from Genetic Engineering and Biotechnology News which cited research findings from the well-respected Fred Hutchinson Cancer Research Center. Researchers there found that men who reported eating French fries, fried chicken, fried fish, and/or doughnuts at least once a week had an increased risk of prostate cancer that ranged from 30–37% as compared to men who said they ate such foods less than once a month. Weekly consumption of these foods was also associated with a slightly greater risk of more aggressive prostate cancer. The effect also appears to be slightly stronger with regard to more aggressive forms of the disease defined by elevated PSA levels or Gleason scores. “For the study, the investigators analyzed data from two prior population-based case-control studies involving a total of 1,549 men diagnosed with prostate cancer and 1,492 age-matched healthy controls. The men were Caucasian and African-American Seattle-area residents and ranged in age from 35 to 74 years.” Further explanation is provided in the linked article. It may be that “we are what we eat.”