Welcome to Weekly Health Update

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

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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 visit our premier global health information website every month.  As always, we enjoy receiving your stimulating feedback and questions, and I will continue to try and personally answer as many of your inquiries as I possibly can.

Welcome to Weekly Health Update

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

SOY, CURCUMIN & PROSTATE CANCER RISK

Because chronic inflammation within the prostate gland is through to be an important risk factor for prostate cancer, anti-inflammatory dietary supplements and medications may be able to reduce the risk of prostate cancer by reducing inflammation.

Isoflavones from soy-based foods are known to act as a weak form of estrogen (the dominant female sex hormone).  Based upon this estrogen-like behavior, as well as potential anti-inflammatory properties, soy isoflavones are being studied as possible prevention and treatment agents for prostate cancer, and other types of cancer. 

Curcumin, which is present in the Indian curry spice turmeric, is also known to have potent anti-inflammatory properties, and has also been the subject of considerable cancer prevention and cancer treatment research.

A newly published prospective, randomized, blinded, placebo-controlled research study, published in the current issue of the journal Prostate, suggests that the combination of soy isoflavones and curcumin may have important potential prostate cancer prevention properties.

In the first part of this study, human prostate cancer cells were treated with a combination of soy isoflavones and curcumin.  Treatment of these human cancer cells with soy isoflavones and curcumin resulted in a significant reduction of prostate-specific antigen (PSA) production by these malignant cells (PSA is a marker of both prostate gland inflammation and prostate gland cancer).

As regular readers of this column are already aware, treatments performed in the laboratory that have beneficial effects on cancer cells, or on mice or rats, do not always have the same positive effects on living, breathing human beings.  Therefore, the findings of the second part of this study are of particular interest.  A total of 85 men with elevated PSA levels, but without prostate cancer (as confirmed by prostate biopsy), were enrolled in the second phase of this intriguing small study.  These 85 men were divided into two groups, and one group received daily supplements containing both soy isoflavones and curcumin, while the second (control) group of men received placebo (sugar) pills that were identical in appearance to the supplement pills (neither the 85 men, nor the nurses who dispensed the supplement pills and placebo pills, were aware of which pills each study volunteer was receiving until after the research study had been completed).

PSA blood levels were tested at the beginning of the clinical portion of this study, and once again 6 months later.  As was observed in the prostate cancer cells during the first part of this study, men with a PSA level of 10, or higher, experienced a significant reduction in their blood PSA levels 6 months after starting daily supplementation with soy isoflavones and curcumin.

Although this brief study cannot definitively confirm that soy isoflavone and curcumin supplements reduce the risk of prostate cancer, their ability to reduce elevated PSA levels in men with chronic prostate inflammation, but without evidence of prostate cancer, at least suggests a potential role in the prevention of prostate cancer (presumably through a reduction in prostate gland inflammation).

While there are multiple human research studies underway that are evaluating the effectiveness of soy isoflavones as cancer prevention agents, currently, there are no major human studies looking at the effects of curcumin on prostate cancer risk.  Based upon the findings of this small, interesting study of soy isoflavones and curcumin, which suggest a potential additive effect on PSA reduction when both of these dietary supplements are taken together, human research trials should be developed to look at the long-term impact, if any, of combined soy isoflavone and curcumin supplementation on prostate cancer risk.

For additional research information on soy isoflavones and curcumin in cancer prevention and cancer treatment, please review the following previous columns:

Soy Foods & Stomach Cancer Risk

Cruciferous Vegetables, Soy & Breast Cancer Risk

Soy Isoflavones & Recurrent Prostate Cancer

Soy Isoflavones Decrease Breast Cancer Recurrence Risk

Genistein (Soy Isoflavone) & Prostate Cancer

Diet, Soy & Breast Cancer Risk

Viagra & Sexual Function in Women; Patient-Reported Adverse Hospital Events; Curcumin & Pancreatic Cancer

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

Dr. Wascher is an oncologic surgeon, a professor of surgery, a cancer researcher, an oncology consultant, and a widely published author  

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

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 visit our premier global health information website every month.  As always, we enjoy receiving your stimulating feedback and questions, and I will continue to try and personally answer as many of your inquiries as I possibly can.

Welcome to Weekly Health Update

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

SOY FOODS & STOMACH CANCER RISK

There is a great deal of interest regarding the potential effects of soy-based foods (like tofu and soy beverages) on cancer risk.  As discussed in my forthcoming book (“A Cancer Prevention Guide for the Human Race”), there is a growing body of laboratory and human research data suggesting that dietary soy isoflavones might be able to reduce the risk of prostate and breast cancer.

Now, a newly published clinical research study from Korea suggests that high levels of soy isoflavones in the blood may also be linked to a reduced risk of stomach cancer, as well.  (Korea has one of the highest incidences of stomach cancer in the world.)  This study appears in the current issue of the journal Cancer Epidemiology, Biomarkers & Prevention.

As most of the published research in the area of cancer prevention is based upon the subjective recall of patient volunteers regarding their diet (and other habits), the authors of this study chose, instead, to directly measure the levels of soy isoflavones in the blood of patient volunteers.  This study included 131 patients with recently diagnosed stomach cancer, and 393 “control” patients who did not have stomach (gastric) cancer.  Blood levels of the two major dietary soy isoflavones (genistein and daidzein) were directly measured in all 524 of these research volunteers, and these results were compared between the patients with stomach cancer and the “control” patients without gastric cancer.

Study volunteers with the highest levels of genistein in their blood, when compared with those with the lowest levels, were found to be 46 percent less likely to be diagnosed with stomach cancer.  Even more impressive was the finding that study volunteers with the highest daidzein blood levels were 79 percent less likely to be diagnosed with stomach cancer when compared to the volunteers with the lowest levels of daidzen in their blood

While there may be other health-related factors at work among the study volunteers with high levels of soy isoflavones in their blood that could explain the much lower stomach cancer risk observed in these same patients, this study’s results are nonetheless intriguing enough to justify a large scale, prospective, randomized, placebo-controlled soy isoflavone clinical research study to confirm the findings of this relatively small Korean public health study.

To learn more about the role of soy isoflavones as potential cancer prevention nutrients, look for the publication of my new landmark evidence-based book, “A Cancer Prevention Guide for the Human Race,” in the summer of this year.

Welcome to Weekly Health Update

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

CRUCIFEROUS VEGETABLES, SOY & BREAST CANCER RISK

The role of soybean-derived isoflavones in cancer prevention is not entirely clear at this time.  However, there has been intense interest in tofu, and other soy-derived foods, as potential breast cancer prevention agents.  At the same time, because genistein, and other soy isoflavones, are known to variably act as both inhibitors and mimics of estrogen (the primary female sex hormone), cancer experts remain divided regarding the safety of regularly consuming soy isoflavones by women who are at an increased risk of developing breast cancer (chronic estrogen stimulation of the breast is a known risk factor for breast cancer).  Meanwhile, the high level of tofu consumption among women in the Far East, coupled with the much lower incidence of breast cancer in those countries when compared to the United States and other western countries, has fuelled speculation that tofu and other soy-derived foods may actually be associated with a reduced risk of breast cancer. 

In addition to soy isoflavones, there is also research data available suggesting that the frequent consumption of cruciferous vegetables, like broccoli and cauliflower, may also be associated with a decreased risk of at least some types of cancer, including breast cancer.

A newly published public health study from Singapore evaluated the impact of the regular intake of vegetables, fruit, and soy-derived foods on the risk of breast cancer within the large Chinese population in that country.  This enormous prospective epidemiological study, which began in 1993, and which appears in the current issue of the American Journal of Clinical Nutrition, included more than 34,000 women volunteers.  All of the 34,018 women in this study underwent detailed evaluation of their diets when they entered into this prospective public health study.  Among this very large group of women, 629 new cases of breast cancer were diagnosed during the course of this ongoing study. 

Based upon their self-reported dietary patterns, the women participating in this large epidemiological study were divided into two groups.  The first group consisted of women who regularly consumed cruciferous vegetables, fruit, and tofu.  The second group of women generally favored meat and starchy foods (such as dim sum), and consumed far fewer portions of vegetables, fruit, and tofu when compared to the first group.

The results of this study indicated that increasing levels of vegetable, fruit and tofu intake were associated with a significant decrease in breast cancer risk in postmenopausal women.   Among the women reporting the highest levels of intake of these foods, there was, on average, a 30 percent reduction in the risk of breast cancer when compared to the women who rarely ate these healthy foods.  Moreover, among the postmenopausal women who frequently consumed vegetables, fruit, and tofu, and who were observed for 5 or more years in this study, the apparent reduction in the risk of breast cancer grew even stronger, and these women were found to be 43 percent less likely to develop breast cancer when compared to women who rarely consumed vegetables, fruit, and tofu in their diets.

Therefore, in this large diet survey-based, prospective public health study,  a diet rich in vegetables (and cruciferous vegetables, such as broccoli and cauliflower, in particular), fruit, and tofu was strongly associated with a significant reduction in breast cancer risk in postmenopausal Chinese women living in Singapore.

Although there remains some concern that soy isoflavones may, under some conditions, actually stimulate the growth of either new or previous breast cancers (or cancers of the ovary or uterus), this public health study’s favorable findings are additive to a growing body of research data suggesting that both cruciferous vegetables and soy-derived isoflavones may be associated with a substantial decrease in the risk of breast cancer in women. 

To learn more about the potential role of cruciferous vegetables and soy isoflavones as part of a cancer prevention lifestyle, look for the publication of my new landmark evidence-based book, “A Cancer Prevention Guide for the Human Race,” in the summer of this year.

Dr. Wascher is an oncologic surgeon, a professor of surgery, a cancer researcher, an oncology consultant, and a widely published author

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Welcome to Weekly Health Update

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

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Welcome to Weekly Health Update

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

SOY ISOFLAVONES REDUCE BREAST CANCER

RECURRENCE RISK

Regular readers of this column are already aware of the controversy surrounding soy isoflavone intake and breast cancer risk.  As happens frequently in clinical research (unfortunately), contradictory research findings have made it difficult to understand the true relationship between dietary soy intake and breast cancer risk (if one exists).  There is, for example, both laboratory and clinical data suggesting that a diet rich in soybean-derived products may be associated with a lower risk of developing breast cancer.  At the same time, because genistein and other dietary isoflavones are known to weakly mimic the effects of estrogen, there has been some concern that a diet rich in isoflavone “phytoestrogens” may increase both the risk of developing a new breast cancer and the risk of developing a recurrence of a previous breast cancer.  (In fact, there is data from laboratory research studies showing that genistein can indeed fuel the growth of human breast cancer cells growing in culture dishes, when exposed to high concentrations of this soy-derived isoflavone.)

A growing body of public health research, primarily from Asian countries where tofu and other soy-based foods are frequently consumed, appears to link increased soy consumption with a decreased lifetime breast cancer risk, particularly when soy-based foods are consumed during adolescence, during the time when development of the female breast is most active (Soy & Breast Cancer Risk).  (Interestingly, there is also recent research suggesting that soy products might also reduce the risk of prostate cancer, which is another hormonally driven cancer:   Genistein & Prostate Cancer Cells, Dietary Soy & Prostate Cancer Risk.)

Although epidemiological research is, increasingly, suggesting that a diet rich in soybean-derived foods might lower a woman’s lifetime risk of developing breast cancer, many breast cancer experts have remained apprehensive regarding dietary isoflavone intake in women with a prior history of breast cancer, in view of the estrogen-like effects of these “phytoestrogens.”  As I have already noted, there is considerable research data available to suggest that soy-derived isoflavones can, at least under certain laboratory conditions, stimulate estrogen-sensitive breast cancer cells to grow and divide.  These research findings have left many oncologists feeling uncomfortable in recommending soy-based foods to their breast cancer patients.  Now, a newly publish public health study in the Journal of the American Medical Association suggests that soy-based foods may actually reduce the risk of breast cancer recurrence, and death due to any cause, in women who have previously been diagnosed with this very common form of cancer.

In this study, which was performed in Shanghai, China, 5,042 female breast cancer survivors (ages 20 to 75 years) were followed for an average of almost 4 years.  All of these patient volunteers underwent detailed surveys regarding their lifestyle habits, including their diets.  These patients, who were originally diagnosed with breast cancer between 2002 and 2006, were surveyed at 6, 18, 36 and 60 months following their original diagnosis with breast cancer.  

The results of this study indicate that the breast cancer survivors who consumed the greatest amount of soy-based foods in their daily diets were 32 percent less likely to experience a recurrence of their breast cancer when compared to the women who consumed the least amount of soy-based isoflavones.  Moreover, the women who consumed the greatest amount of soy were also 29 percent less likely to die, from any cause, when compared to the women who consumed the least amount of soy-derived foods.

A particularly interesting and unexpected finding of this study was that both women with estrogen sensitive breast cancers and women with tumors that were not sensitive to estrogen appeared to experience a significantly decreased risk of breast cancer recurrence if they frequently consumed soy products.  Another important finding of this study was that women who were taking the estrogen-blocking cancer treatment drug tamoxifen also appeared to enjoy a reduced risk of breast cancer recurrence with higher levels of dietary soy intake.  Additionally, the researchers noted that high levels of soy intake appeared to be about as effective in reducing the risk of breast cancer recurrence as the breast cancer prevention drug tamoxifen, alone.

The results of this very important study mirror the findings of the only other prospective clinical study that has looked at the impact of soy-based foods on breast cancer recurrence (the “Life After Cancer Epidemiology,” or “LACE,” study).  The LACE study, which was performed in the United States, followed nearly 2,000 breast cancer survivors for, on average, more than 6 years.  In the LACE study, women who were taking tamoxifen, and who also consumed the highest amount of soy-based dietary isoflavones, were 50 percent less likely to develop a recurrence of their breast cancer when compared to women who reported the lowest consumption of soy-derived foods.

As I have pointed out previously, epidemiological research studies based upon dietary surveys are susceptible to several types of bias which, in turn, can cause researchers to draw the wrong conclusions.  In this case, however, there are now two large prospective cohort studies that have reached essentially the same conclusions (albeit with a rather limited duration of patient follow-up).  Both studies strongly suggest that high levels of soy-based isoflavones in the diet may be able to significantly reduce the risk of breast cancer recurrence.  Based upon the findings of this large Chinese study, the apparent cancer risk reduction effect associated with high levels of soy intake also appears to benefit premenopausal and postmenopausal women, as well as women who are taking the estrogen-blocking drug tamoxifen, women with estrogen-sensitive tumors, and women with (counter-intuitively) estrogen-resistant tumors.

In view of the limited duration of patient follow-up in both of these clinical breast cancer studies, as well as the limitations of survey-based epidemiological research in general, I would like to see updated data from both of these studies after at least 10 years of patient observation before I would be willing to tell my breast cancer patients that they should significantly increase their dietary soy intake.  On the other hand, the rather compelling data presented by both of these clinical research studies will also make me less anxious when any of my breast cancer patients decide, of their own accord, to increase their intake of soy-derived isoflavones.

Note:  Weekly Health Update is currently undergoing an extensive upgrade to better serve its tens of thousands of health-conscious readers around the world.  Beginning in January 2010, newly archived columns will be available by selecting the “Archives” tab on the right side of your screen (all archived columns prior to January 2010 will continue to be available by selecting the “Archives 2007-2009” tab at the top of the screen.)

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

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