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“A critical weekly review of important new research findings for health-conscious readers” 

AVODART (DUTASTERIDE) & PROSTATE CANCER PREVENTION

Because most prostate cancers, like breast cancer, are fueled by sex hormones, the prevention of prostate cancer through the use of hormone-blocking medications is an attractive potential strategy.

Two medications, finasteride (Proscar) and dutasteride (Avodart), are FDA-approved to treat the benign enlargement of the prostate that commonly occurs with increasing age (also known as benign prostatic hypertrophy, or BPH).  Both of these medications have recently been evaluated in prospective, randomized, placebo-controlled clinical research trials as potential prostate cancer prevention agents.  Finasteride and dutasteride are 5-alpha-reductase inhibitors, and function by blocking the conversion of testosterone into dihydrotestosterone by this enzyme (dihydrotestosterone is the biologically active male sex hormone within the prostate gland).  Finasteride inhibits one of the two known forms of 5-alpha-reductase, while dutasteride (Avodart) inhibits both forms.

Finasteride (Proscar) has previously been evaluated in the Prostate Cancer Prevention Trial, which enrolled nearly 19,000 men (55 years of age and older) who were without any clinical evidence of prostate cancer at the time they entered the study.  These men were randomly assigned to receive either finasteride or an identical placebo pill, and the entire cohort of men was then followed for a period of 7 years.  After 7 years of follow-up, 18 percent of the men who had been secretly randomized to receive finasteride were diagnosed with prostate cancer, while 24 percent of the men who had received the placebo pill (unknown to them at the time) developed prostate cancer.  Thus, taking finasteride for 7 years was associated with a 25 percent reduction in the relative risk of prostate cancer during the relatively brief course of this clinical study.  However, a potentially significant downside was also observed in this study, as the men who received finasteride, and who still went on to develop prostate cancer, tended to have more aggressive tumors when compared to the men in the placebo group (37 percent versus 22 percent, respectively).  Moreover, and not surprisingly, since finasteride blocks the active metabolite of testosterone, sexual dysfunction and breast enlargement were more common among the men taking finasteride when compared to the men in the placebo group. 

Following the intriguing results with finasteride (Proscar) in the Prostate Cancer Prevention Trial, there has been a great deal of anticipation building for results of the recently completed dutasteride (Avodart) prostate cancer prevention trial.  Now, the results of this important cancer prevention study have just been published in the New England Journal of Medicine.  This prospective, randomized, blinded, placebo-controlled study lasted for 4 years, and included 6,729 men at high risk of developing prostate cancer.  These men, all of whom were between 50 and 75 years of age, were secretly randomized to receive either 0.5 mg of dutasteride (Avodart) per day or an identical placebo pill.  As part of this research study’s protocol, all of these men underwent needle biopsies of the prostate gland at 2 years and 4 years after entering the study.  By the end of the study, 20 percent of the men who had received dutasteride (Avodart) had developed prostate cancer, while 25 percent of the men in the placebo (control) group were diagnosed with prostate cancer.  Thus, there was an observed 25 percent decrease in the relative risk of prostate cancer among the group of men that was randomized to receive dutasteride (Avodart) for 4 years (and a 5 percent absolute reduction in prostate cancer risk with Avodart).  As was observed in the finasteride (Proscar) study, however, there was also a higher incidence of more aggressive (i.e., higher grade) tumors observed among the men who took dutasteride (Avodart) when compared to the men in the placebo group, although only a very small number of these high grade tumors were identified in either group of men.  Finally, and not surprisingly, the symptoms of benign prostatic hypertrophy (BPH), including difficulties in passing urine, were much improved among the men randomized to take dutasteride (Avodart).

Because it is still too soon to determine whether or not finasteride or dutasteride are able to significantly reduce the risk of death due to prostate cancer, there is no consensus at this time, among most prostate cancer experts, regarding the use of these hormone-blocking agents as prostate cancer prevention agents.  However, for men with significant prostate cancer risk factors, it may be prudent to consider the use of Proscar or Avodart.

To learn more about the potential role of 5-alpha-reductase inhibitors in cancer risk reduction, look for the publication of my new landmark book, “A Cancer Prevention Guide for the Human Race,” in the spring/summer of this year.

http://www.youtube.com/watch?v=7-Tdv7XW0qg

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http://www.imcworldwide.org/haiti

Welcome to Weekly Health Update

“A critical weekly review of important new research findings for health-conscious readers” 

SOY ISOFLAVONES & RECURRENT PROSTATE CANCER

The interest level in natural and complementary treatments for cancer has never been higher in the medical and scientific communities than it is now.  For decades, now, this area of research was often relegated to the fringes of the clinical research community, while most mainstream academic research centers and Big Pharma companies focused on the design and testing of new biochemical therapies with improved therapeutic and safety profiles.  With the 5-year overall survival rate among all patients with cancer approaching a record 65 percent, we have, unquestionably, made enormous improvement in our ability to cure many of the cancers that, not too long ago, were associated with a very high risk of death.  Cancer physicians also have far more effective medications available now to control the noxious side effects of many of our “front-line” cancer therapies, which have had the beneficial effect of further reducing suffering and morbidity among thousands of cancer patients as they undergo their daily treatments. 

Despite the  admirable (and ongoing) progress that has been achieved over the past four decades in cancer care, however, nearly 600,000 cancer patients will still succumb to their disease this year in the United States, alone.  Thus, more effective cancer prevention strategies are necessary to reduce the number of new cases of cancer, and more effective (and less toxic) cancer therapies must be identified.  Moreover, with the annual cost of many new cancer therapies now running into the hundreds-of-thousands of dollars per patient, per year, our already unsustainable (and still rising) health care costs demand that the cancer care community rigorously evaluate less costly approaches to cancer prevention and treatment.

Because so-called “natural products” are relatively inexpensive, widely available, and generally non-toxic, there is a growing interest in studying these agents using the same high-level prospective, randomized clinical trials that are routinely used by pharmaceutical companies and academic medical centers to evaluate promising new drug therapies.  Because of their great complexity and high cost, however, randomized clinical trials are best reserved for studying novel therapies for which there is at least some laboratory (“preclinical”) or early-phase clinical data available that suggests some potential benefit to humans.  Until recently, however, and most likely due to inherent biases against natural products by the mainstream clinical research community in the past, very little high-level clinical research has been performed to definitively evaluate natural products as disease prevention and treatment agents.  Fortunately, and despite shrinking research funding over the past decade, there has been a recent surge in the number of large randomized, prospective, controlled clinical research trials reporting their findings of the effects of natural products on disease prevention and treatment.

As the vast majority of natural products and lifestyle-related research in the past has been based upon low-powered research methods, it should come as no surprise that recent high-level prospective clinical research studies have, more often than not, found little or no benefit associated with the use of many of these supplements and products.  (Moreover, in some cases, several very popular and highly recommended vitamins and dietary supplements have actually been found to be potentially harmful.)   However, a great deal of promising high-level clinical research has yet to be done in order to fully and accurately assess the, literally, hundreds of natural products for which there is at least some preclinical data supporting potentially beneficial health effects.  (In my forthcoming book, “A Cancer Prevention Guide for the Human Race,” I will be comprehensively reviewing and analyzing the available laboratory and clinical research data on natural products and lifestyle strategies as an integral approach to a cancer prevention lifestyle.  The publication of this groundbreaking and authoritative evidence-based cancer prevention guide is tentatively scheduled for May of this year.)

In many respects, prostate cancer is the male counterpart of breast cancer in women.  Analogous to breast cancer in women, prostate cancer is the most common cancer that occurs in men (excluding minor skin cancers), and the second most common cause of cancer death.  In 2009, an estimated 192,000 new cases of prostate cancer were diagnosed in the United States alone, and approximately 27,000 American men died of this disease in the same year.  In most industrialized nations, prostate cancer accounts for approximately 25 percent of all cancer diagnoses in men (similar to the percentage of breast cancer cases among all cancer cases diagnosed in women).

A newly published prospective, early-phase, clinical pilot study from Canada evaluated the effects of a soy beverage (“soy milk”) on the progression of recurrent prostate cancer in 29 men following radiation therapy for their cancers.  This study, which has just been published in the journal Nutrition and Cancer, was not a placebo-controlled randomized study, however, this small phase II clinical study prospectively followed these patient volunteers for 6 months, during which time serial measurements of the level of prostate-specific antigen (PSA) in their blood was performed (PSA is the primary prostate tumor marker that is measured both to detect early prostate cancer and to identify recurrences of this type of cancer.)

The time interval during which the level of PSA in the blood doubles is an important indicator of the rate of progression of recurrent prostate cancer.  In this small prospective clinical pilot study, the consumption of approximately 500 ml of soy beverage per day, for 6 months, was associated with an actual decline in PSA levels in 4 (14 percent) of these patient volunteers, while another 8 (28 percent) of these recurrent prostate cancer patients experienced a greater than 100 percent increase in their PSA doubling times.  However, another 5 patients (17 percent) experienced a 50 percent or greater decrease in their PSA doubling times during the 6 month duration of this study, which was an unfavorable development.  Thus, during the brief duration of this intriguing small pilot study, 42 percent of men with early recurrence of their prostate cancer experienced either a decrease in the biochemical extent of their recurrent cancers or a significant biochemical slowing of the progression of their recurrent disease.

Whether or not longer durations of soy intake will be able to sustain the impressive results of this study is not clear at this time.  More importantly, whether or not these observed favorable effects of daily soy intake on PSA levels and PSA doubling times will actually translate into prolonged survival (or not) is also unknown at this time.  It will require several larger and longer-term randomized, placebo-controlled, blinded, prospective clinical trials of soy foods and soy isoflavone supplements to answer these critical questions (several of which are already underway).  Meanwhile, the overall safety profile for moderate amounts of soy intake in men appears to be quite favorable, and so many prostate cancer experts are cautiously recommending soy-derived foods for men with prostate cancer, and for men who are at an increased risk of developing prostate cancer, pending the completion of these larger prostate cancer research studies.

For a much more detailed and comprehensive evaluation of the role of soy foods, and other dietary supplements and lifestyle modifications, in the prevention of prostate cancer (and other cancers), look for the publication of “A Cancer Prevention Guide for the Human Race” in the spring of this year.

I and the staff of Weekly Health Update would like to take this opportunity to thank the more than 100,000 new and returning readers who have visited our premier global health information website this month, alone.  As always, we enjoy receiving your feedback and questions, and I continue to try to personally answer as many of your inquiries as I possibly can.

In view of the extreme devastation and human misery brought about in Haiti and Chile by the recent earthquakes, Weekly Health Update asks our tens of thousands of caring readers to give generously to established charities that are currently working in that country to assist the injured, the ill, and the homeless there.  There are many such legitimate charities, including the following two:

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Welcome to Weekly Health Update

“A critical weekly review of important new research findings for health-conscious readers”

EXERCISE & PROSTATE CANCER RISK

There is an increasing body of research evidence to suggest that many cases of cancer can be prevented through lifestyle and diet modifications.  Indeed, even conservative estimates suggest that more than 60 percent of new cancer cases could be prevented simply by abstaining from unhealthy lifestyle and dietary habits.  (More enthusiastic cancer prevention experts have suggested that 80 percent of cancer cases, or more, might be preventable with rigorous lifestyle and diet changes.)   Given that, in the best case, modern cancer treatment results in the long-term survival of only about 60 percent of all cancer patients, and that the survival rate for many of the most lethal cancers still remains far more dismal, an ounce of cancer prevention is certainly worth much more than a pound of cancer cure.  (This simple yet profound realization is the central theme of my new book, “A Cancer Prevention Guide for the Human Race,” which will be published in the spring of 2010.) 
 
As a practicing comprehensive Surgical Oncologist, I routinely treat patients with highly lethal cancers, many of which are, sadly, incurable by the time they are diagnosed.  While not every case of cancer can be prevented through lifestyle and diet modification, many of the terrible, and ultimately fatal, cancer cases that I routinely see might have been prevented with reasonably moderate alterations in the way that people choose to live their daily lives.
 
Prostate cancer is the most common non-skin cancer that occurs in men, and the second most common cause of cancer death in men.  In 2009, an estimated 192,000 new cases of prostate cancer will be diagnosed, and approximately 27,000 men will die of this disease.  Prostate cancer currently afflicts 1 out of every 6 American men during their lifetimes, and accounts for 25 percent of all cancer diagnoses in men (similar, I might add, to the percentage of breast cancer cases among all cancer cases diagnosed in women).  Most prostate cancers are stimulated to grow and spread by testosterone and other androgens produced by the testes, and by other tissues in the body. 
 
The relationship between prostate cancer risk and exercise has not been entirely clear, thus far, as various clinical studies have produced contradictory findings.  Some of these studies have suggested that high levels of daily physical activity may reduce the risk of prostate cancer, while other studies have not confirmed a link between prostate cancer risk and physical activity levels.
 
A new prospective public health study, just published in the British Journal of Cancer, adds further important evidence that increased levels of physical activity may indeed reduce the risk of developing prostate cancer.  In this newly published study, nearly 46,000 men between the ages of 45 and 70 years were prospectively followed between 1998 and 2007.  All of these male volunteers completed extensive questionnaires regarding their daily levels of physical activities at 30 years of age and at 50 years of age, as well as at the time or their entry into this clinical study.  These questionnaires specifically included questions regarding walking or bicycling; current waist, hip and height measurements; education level; cigarette smoking; alcohol consumption; diabetes; family history of prostate cancer; and other lifestyle factors.  Six predefined activity levels for occupational activity (from “mostly sitting down” to “heavy manual labor”), and additional predefined categories for time spent on different activities, were specifically included in the questionnaire, such as walking or bicycling (“hardly ever” to “more than 90 min per day”), home or household work (“less than 1 hour per day” to “more than 8 hours per day”), inactive leisure time (“from 2 hours per day or less” to “5 hours per day or more”), and active leisure-time exercising (“from less than 1 hour per week” to “more than 5 hours per week”).  The patient volunteers were also queried regarding the average number of hours per day they spent sleeping. 
 
Importantly, the researchers conducting this study took the extra step of conducting 7-day physical activity evaluations to verify that the study’s participants actually engaged in the levels of physically activity that they claimed on the questionnaires.  (This additional validation step confirmed the accuracy of the questionnaire information supplied by the study’s volunteers.)  The incidence of prostate cancer, and the death rate associated with prostate cancer, among these 45,887 middle-aged and elderly men were then analyzed at the conclusion of this very large prospective epidemiological study. 
 
When the men who engaged in physical activity at the highest levels were compared with those at the lowest levels, some very important differences in prostate cancer risk emerged.  Overall, very high levels of physical activity were associated with a 16 percent reduction in the risk of developing prostate cancer.  Additionally, among the men who spent at least half of their work days being physically active, the risk of prostate cancer was 20 percent lower when compared to men who spent most of their work day sitting down.  Specifically, and very importantly, there appeared to be a linear and progressive decrease in prostate cancer risk with each additional 30 minutes of walking or bicycling per day over the course of the adult lifetimes of these men (this linear relationship was noted within a range of 30 to 120 minutes of walking or bicycling per day).  Additionally, the risk of developing advanced prostate cancer appeared to be further lessened by regular daily physical activity. 
 
The results of this study mirror those of other high-quality cancer prevention studies for other types of cancer (including, most notably, breast cancer).  While clinical research studies such as this one are prone to various forms of bias, and in particular, biases that arise from patients “self-reporting” their personal health and lifestyle information on study questionnaires, the authors of this study appear to have taken very significant and effective steps to reduce the risk of including such biases in the data that they collected from these nearly 46,000 men.  Therefore, although a small degree of residual error cannot be completely excluded from the results of this impressive epidemiological study, its findings that progressively higher levels of daily physical activity (and, it must be stressed, throughout one’s lifetime) are associated with a decreasing level of prostate cancer risk are very likely to be valid even in the presence of small errors in the study’s data (if they exist).
 
Cardiovascular disease remains the most common cause of premature death in most societies.  Cancer is the number two cause of premature death when including people of all ages, and the number one cause of premature death below the age of 80 in the United States.  Regular exercise, including relatively moderate activities such as brisk walking or bicycling, have been shown to significantly reduce the risk of death due to cardiovascular disease, as well as, increasingly, the risk of developing or dying from multiple different types of cancer.  Based upon the results of this well designed and well executed prospective clinical research study, it would appear that prostate cancer can be added to the list of life-threatening illnesses for which the risk can be decreased through regular and frequent physical activity (and both at work and at home).

Disclaimer: As always, my advice to readers is to seek the advice of your physician before making any significant changes in medications, diet, or level of physical activity