Updates on Active Surveillance (AS) for 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.

 

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