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Chicken skin and eggs increases prostate cancer recurrence:

Jacob Schor ND, FABNO

May 15, 2010

 

An interesting study was published in March of this year that adds to our understanding of factors that affect prostate cancer recurrence and progression.  Conducted by Erin Richman and colleagues at Harvard, it was published in the arch issue of Clinical Nutrition.  These same Harvard researchers have given us other useful information in past years.  This current paper by Richman was a prospective trial in which consumption of processed and unprocessed red meat, fish, poultry, and eggs was examined to see if eating any of these foods affected the risk of prostate cancer recurrence or progression.

 

Reference: Richman EL, Stampfer MJ, Paciorek A, Broering JM, Carroll PR, Chan JM.  Intakes of meat, fish, poultry, and eggs and risk of prostate cancer progression.  Am J Clin Nutr. 2010 Mar;91(3):712-21.

 

Data was collected from 1,294 men, already diagnosed with prostate cancer and participating in the Cancer of the Prostate Strategic Urologic Research Endeavor, who had not had recurrence or progression as of 2004-2005.  These men were followed for an average of 2 years.

During the two years of the study, 127 events were observed.  Events were defined as prostate cancer death, metastases, elevated prostate-specific antigen or secondary treatment.

The most important finding was that greater consumption of eggs or poultry with skin on it was associated with 2-fold increases in risk when a comparison was made between those who ate the most with the least of either eggs or chicken with skin.  Men with higher prognostic risk at diagnosis, that is had a higher Gleason score, and a high poultry intake, had a 4-fold increased risk of recurrence or progression compared with men with low/intermediate prognostic risk and a low poultry intake (P for interaction = 0.003).  This study did not find a connection between eating processed or unprocessed red meat, fish, or skinless poultry after prostate cancer diagnosis with prostate cancer recurrence or progression.

These data may, at least for the time being, change what we tell men with prostate cancer.  I write, “for the time being” as these kinds of studies are famous for ‘changing their minds’ as new data accumulate. 

 

[My esteemed colleague, Steve Austin’s response after reading these findings was, “I've grown leery over the years in putting too much stock in observational reports.  Often the findings fall apart when intervention trials are run.”  Yet he wisely adds, “However, when it comes to stuff like this, a prospective observation is probably the best we'll ever do.”]

 

Of the approximately 192,280 cases of prostate cancer diagnosed in 2009, over 90%, are still in the localized or regional stages for which 5-year survival is almost 100%.   In cases of distant metastases, 5-year survival drops to only 32%.  

 

Identifying factors, which patients can change, that may affect progression of prostate cancer for the better is important.  Certain foods are associated with increasing or decreasing risk of getting prostate cancer.  Researchers in the past have suggested that a, “… diet low in fat, high in vegetables and fruits, and avoiding high energy intake, excessive meat, excessive dairy products and calcium intake, is possibly effective in preventing PC.”

These studies generally assume that the same factors that increase the risk of getting prostate cancer in the first place, will affect existing cancer similarly.  The truth is that we know a lot less about dietary factors that may affect recurrence and progression.

A 2006 study reported that eating a lot of fish or tomato sauce after diagnosis decreased the risks of recurrence and progression: “Men in the highest versus lowest quartile of post-diagnostic fish consumption had a multivariate hazard ratio (HR) of progression of 0.73 … the comparable HR for tomato sauce was 0.56 …”    In other words, the guys who ate the most fish had a 27% lower risk while those who ate the most tomato sauce  had a 44% lower risk of recurrence or progression.

The Richman et al., the authors of the current study, had expected that eating processed meat or red meat, because of their high saturated fat content, would increase risk of progression.  They also assumed that poultry and eggs, because they contained lower levels of saturated fat and because they contained more omega-3 fats, would lower risk.  They were wrong on all counts. 

They found, “… no evidence of an association between processed red meat, unprocessed red meat, or fish with prostate cancer progression.”  They did find “… an increased risk of prostate cancer progression associated with higher poultry intake that was not statistically significant.”  There was a, “… significant 2-fold increased risk of prostate cancer progression among men in the highest quartile of egg intake compared with the lowest quartile.”  Translated that means that those eating an average of five and a half eggs a week were twice as likely to have their cancer return or progress compared to the guys that ate less than a single egg in a two-week period.

It was when the poultry data was broken down to compare the data from men who ate their birds skinless with men who preferred their birds with skin attached, that striking results occurred.   Eating skinless poultry did not increase risk of cancer recurrence or progression, but eating poultry with skin, more than doubled the risk.

How much of this should we believe?  Admittedly this study wasn’t perfect; the short follow-up time produced a relatively small number of cases of recurrence or progression from which to analyze and compare data.  Information on what the men ate before they got prostate cancer was not collected.  Eating skinless poultry may have been a marker for those men attempting to make more aggressive dietary changes.  Thus the skinless eaters may have made other changes in their life styles that could explain the effect.

A 2004 review found no association between eggs or poultry and the risk of initially getting prostate cancer.   In 2007, researchers suggested that there could be different factors that promote prostate cancer after diagnosis than may have initially triggered the cancer.   Still other factors may be responsible for determining how aggressive the cancer will be.

As a side note, this last study from 2007 reported that increased levels of alpha-linolenic acid in the diet were associated with higher risks of prostate cancer, a troubling piece of information.  The prime source of this fatty acid is flax seed oil.  Many men with prostate cancer, under the impression that flax oil fights prostate cancer, consume large quantities of flax oil.  This study suggests they may be making matters worse. 

This is not the first time poultry has been linked with prostate cancer.  The American Institute of Cancer Research suggested a possible association between total poultry and prostate cancer in their 2007 report.    A 2001 study reported an association between poultry skin and risk of metastatic prostate cancer.

The authors of this current study, Richman et al., had thought that levels of saturated fat in foods would be the main predictor of risk.  Because their results do not support this idea, they have proposed an alternative explanation for their findings.  Eating poultry skins may cause enough of an increase in heterocyclic amines as to change the risk of cancer recurrence.

This idea isn’t new.  “Others [have] suggested [an] association with higher meat intake, possibly due to heterocyclic amines and polycyclic aromatic hydrocarbons, produced during grilling or frying…” with prostate cancer.

Poultry contains more heterocyclic amines than any other type of meat.  This has led to some interesting theories as heterocyclic amine,

“… intakes were estimated to be greatest for African American males, who were estimated to consume approximately 2- and approximately 3-fold more [heterocyclic amines] than white males …. This difference … may at least partly explain why prostate cancer (PC) kills approximately 2-fold more African American than white men ….”

This current study adds to our knowledge of specific dietary advice we might give to men who have been diagnosed with prostate cancer.

It does something else though.  It gives us a very different angle from which to approach this cancer.  Rather than just focusing on treatments and supplements that kill cancer cells we can also seek ways to lower heterocyclic amines.  Food can be prepared in different ways to lower production of these unwanted chemicals.  Bowel flora can be changed to increase break down of these chemicals before they are absorbed.  Even something as simple as eating yogurt or drinking beer with meals may help. The liver can be stimulated to speed their elimination.  There’s more that we can do to control exposure and levels of heterocyclic amines than simply avoiding chicken skin.

Related newsletters:

Sleep Duration and risk of Breast or Prostate Cancer:

Sleeping less than 7 hours a night incresaes risk of hormone triggered cancers.

http://denvernaturopathic.com/sleepdurationCancer.htm

Vitamin D update, good for prostate etchttp://denvernaturopathic.com/news/PCUpdate609.html

Board Meetings and Iced Tea Recipe: Both Green tea and pomegranate juice have been shown to be protective against prostate cancer.  Why not mix them together? http://denvernaturopathic.com/boardmeetingsandicedtea.htm

Metabolic Syndrome, Vitamin D and Prostate Cancer

If you are a fat guy with high blood pressure and low HDL cholesterol, you had better spend plenty of time in the sun.  Low vitamin D levels will increse your risk of prostate cancer by a factor of 8.

http://denvernaturopathic.com/news/metabolicsyndromeVitaminD.html

Prostate Cancer and Pomegranate Juice

Pomegranate juice triples PSA doubling time in trial of men with metastatic prostate cancer. http://denvernaturopathic.com/news/PomandPC.html

Aleve makes vitamin D more effective against prostate cancer: http://denvernaturopathic.com/news/DandAleve.html

Barbecue and Cherries:  Tricks to reduce heterocyclic amines in food: http://denvernaturopathic.com/barbecueandCherries.htm

Am J Clin Nutr. 2010 Mar;91(3):712-21. Epub 2009 Dec 30.

Intakes of meat, fish, poultry, and eggs and risk of prostate cancer progression.

Richman EL, Stampfer MJ, Paciorek A, Broering JM, Carroll PR, Chan JM.

Department of Epidemiology, Harvard School of Public Health, Boston, MA, USA. erichman@hsph.harvard.edu

Abstract

BACKGROUND: Processed meat and fish have been shown to be associated with the risk of advanced prostate cancer, but few studies have examined diet after prostate cancer diagnosis and risk of its progression. OBJECTIVE: We examined the association between postdiagnostic consumption of processed and unprocessed red meat, fish, poultry, and eggs and the risk of prostate cancer recurrence or progression. DESIGN: We conducted a prospective study in 1294 men with prostate cancer, without recurrence or progression as of 2004-2005, who were participating in the Cancer of the Prostate Strategic Urologic Research Endeavor and who were followed for an average of 2 y. RESULTS: We observed 127 events (prostate cancer death or metastases, elevated prostate-specific antigen concentration, or secondary treatment) during 2610 person-years. Intakes of processed and unprocessed red meat, fish, total poultry, and skinless poultry were not associated with prostate cancer recurrence or progression. Greater consumption of eggs and poultry with skin was associated with 2-fold increases in risk in a comparison of extreme quantiles: eggs [hazard ratio (HR): 2.02; 95% CI: 1.10, 3.72; P for trend = 0.05] and poultry with skin (HR: 2.26; 95% CI: 1.36, 3.76; P for trend = 0.003). An interaction was observed between prognostic risk at diagnosis and poultry. Men with high prognostic risk and a high poultry intake had a 4-fold increased risk of recurrence or progression compared with men with low/intermediate prognostic risk and a low poultry intake (P for interaction = 0.003). CONCLUSIONS: Our results suggest that the postdiagnostic consumption of processed or unprocessed red meat, fish, or skinless poultry is not associated with prostate cancer recurrence or progression, whereas consumption of eggs and poultry with skin may increase the risk.

PMID: 20042525 [PubMed - indexed for MEDLINE]

http://www.cancer.gov/cancertopics/types/prostate

Cancer Statistics Review SEER. 1975-2005 in: RiesL, Melbert D, Krapcho M, et al. eds. Bethesda, MD: National Cancer Institute 2007. http://seer.cancer.gov/csr/1975_2005/

J Hum Nutr Diet. 2009 Jun;22(3):187-99; quiz 200-2. Epub 2009 Apr 1.

A systematic review of the effect of diet in prostate cancer prevention and treatment.

Ma RW, Chapman K.

Faculty of Medicine, University of New South Wales, Sydney, NSW, Australia. robertm_scholl@hotmail.com

Abstract

Dietary therapy has been proposed as a cost effective and noninvasive means of reducing the risk of prostate cancer (PC) and its progression. There is a large volume of published studies describing the role of diet in the prevention and treatment of PC. This article systematically reviews the data for dietary-based therapy in the prevention of PC, as well as in the management of patients with PC, aiming to provide clarity surrounding the role of diet in preventing and treating PC. Although conclusive evidence is limited, the current data are indicative that a diet low in fat, high in vegetables and fruits, and avoiding high energy intake, excessive meat, excessive dairy products and calcium intake, is possibly effective in preventing PC. However, caution must be taken to ensure that members of the public do not take excessive amounts of dietary supplements because there may be adverse affects associated with their over consumption. The dietary recommendations for patients diagnosed with PC are similar to those aiming to reduce their risk of PC.

Cancer Causes Control. 2006 Mar;17(2):199-208.

Diet after diagnosis and the risk of prostate cancer progression, recurrence, and death (United States).

Chan JM, Holick CN, Leitzmann MF, Rimm EB, Willett WC, Stampfer MJ, Giovannucci EL.

Department of Epidemiology, University of California, Room A622, San Francisco, CA, 94143-1695, USA. june@uorg.ucsf.edu

Abstract

OBJECTIVES: We examined post-diagnostic diet and risk of cancer progression in a cohort of men with prostate cancer from the Health Professionals Follow-up Study. METHODS: We observed 392 progression outcomes among 1,202 men diagnosed with incident localized/regional prostate cancer between 1986 and 1996. Men completed prospective dietary surveys before and after diagnosis and were followed through 2000. We examined post-diagnostic consumption of red meat, grains, vegetables, fruits, milk, tomatoes, tomato sauce, and fish as predictors of progression using Cox proportional hazard regression models adjusted for total energy, age, clinical factors, and pre-diagnostic diet. RESULTS: Men in the highest versus lowest quartile of post-diagnostic fish consumption had a multivariate hazard ratio (HR) of progression of 0.73 (95% CI 0.52-1.02); the comparable HR for tomato sauce was 0.56 (95% CI 0.38-0.82). We observed inverse linear relationships for fish and tomato sauce and risk of progression (HR = 0.83, p-value = 0.006 and HR = 0.80, p-value = 0.04 for a two serving/week increase of fish and tomato sauce, respectively). Milk and fresh tomato consumption were associated with small elevations in risk. CONCLUSIONS: These data suggest that diet after diagnosis may influence the clinical course of prostate cancer, and fish and tomato sauce may offer some protection against disease progression.

Dagnelie PC, Schuurman AG, Goldbohm RA, Van den Brandt PA. Diet, anthropometric measures and prostate cancer risk: a review of prospective cohort and intervention studies. BJU Int. 2004 May;93(8):1139-50.

Giovannucci E, Liu Y, Platz EA, Stampfer MJ, Willett WC. Risk factors for prostate cancer incidence and progression in the health professionals follow-up study.  Int J Cancer. 2007 Oct 1;121(7):1571-8.

World Cancer Research Fund.  American Institute of Cancer Research. Food, nutrtition, physical activity and the prevention of cancer: a global perspective.  Washington, DC. 2007.

Michaud DS, Augustsson K, Rimm EB, Stampfer MJ, Willet WC, Giovannucci E. A prospective study on intake of animal products and risk of prostate cancer. Cancer Causes Control. 2001 Aug;12(6):557-67.

Stacewicz-Sapuntzakis M, Borthakur G, Burns JL, Bowen PE. Correlations of dietary patterns with prostate health.  Mol Nutr Food Res. 2008 Jan;52(1):114-30.

Bogen KT, Keating GA. U.S. dietary exposures to heterocyclic amines.  J Expo Anal Environ Epidemiol. 2001 May-Jun;11(3):155-68.