Population-wide PSA screening: no reduction in deaths

Prostate cancer is exceedingly common, especially with age. It estimated from autopsy studies that one-third of men in their forties have prostate cancer, and by age 85, that figure increases to as high as 75%.1,2 However, most of these cases of prostate cancer are not actually life-threatening. U.S. The lifetime risk of a diagnosis is 15.9%, but the lifetime risk of death from prostate cancer is only 2.8%. Even without treatment, most prostate cancers are not deadly.2 Most men with prostate cancer die from other causes, not from prostate cancer.

Because of the low risk of death from prostate cancer, there is controversy regarding population-wide PSA screening of men without symptoms suggesting prostate cancer. There is no distinction by the PSA between disease that is likely or unlikely to progress to a life-threatening disease. So should all men be screened?

Blood in vials. Flickr: Kenny Holston 21

The most important question is this: Does screening reduce the risk of dying from prostate cancer?
The U.S. Preventive Services Task Force, an impartial agency that assesses scientific evidence on prevention and primary care, issued a statement in 2008 saying that they had found “insufficient evidence that screening for prostate cancer improved health outcomes” in men younger than 75. In men 75 or older, the USPSTF found that “the harms of screening and treatment outweigh any potential benefits.”3

New evidence that screening does not reduce death rates
A long-term study published in January 2012 has not found any decrease in prostate cancer deaths in men undergoing annual screening compared to a control group. The Prostate, Lung, Colorectal, and Ovarian cancer screening trial (PLCO trial) of over 76,000 men had published intermediate results after 10 years of follow up, and were not updating that study, extending to 13 years of follow up. The results were similar after 13 years: about 12% more cancers were diagnosed in the screening group, but death rates were not different between the two groups, suggesting that population-wide screening does not reduce the number of prostate cancer deaths.4

This report comes on the heels of a meta-analysis of PSA screening trials performed for the USPSTF in October 2011, which reported information from 5 trials (including the 10-year data from the PLCO trial). Collectively analyzing data from these trials, the authors concluded that PSA screening “results in small or no reduction in prostate cancer-specific mortality.”5

Could PSA screening be harmful?
Despite the above evidence, the idea of screening is still attractive – if you had prostate cancer, wouldn’t it be better to know it? Maybe not.

PSA screening is known to produce many false-positive results - about 70% of men who have elevated PSA levels do not actually have cancer.6 Certainly, psychological harms are inherent in false-positive results, although there is insufficient research to estimate the extent of this harm.5

Healthy men who undergo annual screening may expose themselves to unnecessary and potentially harmful treatments:

  • Prostate biopsy complications include fever, infection, bleeding, pain, and urinary difficulty in some men.
  • If an abnormal PSA followed by prostate biopsy does indeed detect cancer, 90% of men will be treated with surgery, radiation, or androgen deprivation therapy.
    • Up to 0.5% of men die within 1 month of prostate cancer surgery, and 0.6-3% have cardiovascular events. One to seven percent will have serious complications. Radiation and surgery have adverse effects including urinary continence and erectile dysfunction in 20-30% of men. Radiation is also associated with bowel dysfunction.2, 3
    • Androgen deprivation therapy for localized prostate cancer is associated with erectile dysfunction in about 40% of men. Additional serious harms have been reported in patients receiving androgen deprivation therapy for advanced prostate cancers, including increased risk of heart disease, diabetes and bone fractures.2,3,7

Since most cases of prostate cancer are not life-threatening, these procedures are often unnecessary.

The U.S. Preventive Services Task Force (USPSTF) is currently revising their screening recommendations.
As of now, a draft version of the new recommendations is available. In short:

“…the USPSTF now recommends against PSA-based screening for prostate cancer in all age groups.”2

For real protection against cancer, we must focus on prevention rather than relying on early detection. A diet based on beneficial plant foods with documented anti-cancer properties is much more reliable than PSA screening, and protects against heart disease, diabetes, and all cancers, not just prostate cancer. A healthful, plant-based diet is also effective at halting the progression of prostate cancer.8-11

To learn more about protecting yourself from prostate cancer, read my 10 strategies for preventing prostate cancer. Also, in my most recent book, Super Immunity, I discuss the latest scientific research on super foods that supercharge the immune system and fight cancer, and I explain how to put this knowledge into practice by following an anti-cancer eating style.

 

References:

 

1. Sakr WA, Haas GP, Cassin BF, et al: The frequency of carcinoma and intraepithelial neoplasia of the prostate in young male patients. J Urol 1993;150:379-385.
2. Screening for Prostate Cancer: U.S. Preventive Services Task Force Recommendation Statement DRAFT. U.S. Preventive Services Task Force; 2011.
3. Screening for Prostate Cancer: U.S. Preventive Services Task Force Recommendation Statement. 2008.
4. Andriole GL, Crawford ED, Grubb RL, 3rd, et al: Prostate Cancer Screening in the Randomized Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial: Mortality Results after 13 Years of Follow-up. J Natl Cancer Inst 2012;104:125-132.
5. Chou R, Croswell JM, Dana T, et al: Screening for prostate cancer: a review of the evidence for the U.S. Preventive Services Task Force. Ann Intern Med 2011;155:762-771.
6. Esserman L, Shieh Y, Thompson I: Rethinking Screening for Breast Cancer and Prostate Cancer. JAMA: The Journal of the American Medical Association 2009;302:1685-1692.
7. Robinson D, Garmo H, Lindahl B, et al: Ischemic heart disease and stroke before and during endocrine treatment for prostate cancer in PCBaSe Sweden. Int J Cancer 2012;130:478-487.
8. Frattaroli J, Weidner G, Dnistrian AM, et al: Clinical events in prostate cancer lifestyle trial: results from two years of follow-up. Urology 2008;72:1319-1323.
9. Fuhrman J: Dr. Joel Fuhrman Case Study Series: Prostate Cancer.
10. Ornish D, Magbanua MJ, Weidner G, et al: Changes in prostate gene expression in men undergoing an intensive nutrition and lifestyle intervention. Proc Natl Acad Sci U S A 2008;105:8369-8374.
11. Ornish D, Weidner G, Fair WR, et al: Intensive lifestyle changes may affect the progression of prostate cancer. J Urol 2005;174:1065-1069; discussion 1069-1070.

 

Pistachio nuts may improve erectile function

Pistachio nuts have a unique nutritional profile – they are especially rich in plant sterols, carotenoids, tocopherols (vitamin E), and arginine.  Plant sterols are structurally similar to cholesterol, and provide a cholesterol-lowering benefit.1 All nuts have cholesterol-lowering and other cardioprotective effects, but pistachios (in a tie with Mediterranean pine nuts) have the highest plant sterol content of all nuts.  Studies investigating the effects of pistachios on cardiovascular disease risk factors not only reported reduced cholesterol levels, but also decreased inflammatory markers, increased blood antioxidant levels and reduced oxidative stress.2-4 In addition to antioxidants and plant sterols, pistachios are also rich in arginine, an amino acid that is involved in nitric oxide production, which regulates relaxation of arterial smooth muscle and therefore blood flow.  In a previous study, pistachio supplementation resulted in enhanced endothelial cell function, which means that nitric oxide availability was increased.4

Pistachios. Flickr: theogeo

Erectile dysfunction (ED) is primarily a disorder of penile blood flow, most often accompanied by chronic conditions that affect the vasculature, such as diabetes, hypertension, and high cholesterol. Atherosclerosis in peripheral arteries is known to contribute to the impaired blood flow in this condition.  Atherosclerosis is usually preceded by endothelial dysfunction, which decreases nitric oxide bioavailability, leading to impaired blood flow regulation.  Since pistachios have confirmed cholesterol-lowering effects and are rich in arginine (which helps to produce nitric oxide), scientists tested whether pistachios could enhance erectile function in men with ED.

Subjects in the study consumed 100 grams of pistachio nuts (about 3 ounces) each day for three weeks. Erectile function was evaluated by subjects’ reports and also by blood flow measurement with ultrasound.  After three weeks of pistachio supplementation, both the erectile function scores based on subjects’ reports and the velocity of penile blood flow were improved.  The men’s cholesterol levels also improved.5

The health of the heart and blood vessels is crucial to the health of the entire body.  Eating to restore cardiovascular health will improve blood flow and nutrient delivery to all tissues, improving overall health. Like several other chronic diseases, erectile dysfunction shares the same risk factors with cardiovascular disease.  Antioxidants, plant sterols, and arginine promote blood vessel health and are provided in abundance by a high nutrient diet made up of whole plant foods.

 

References:

1. Ellegard LH, Andersson SW, Normen AL, et al: Dietary plant sterols and cholesterol metabolism. Nutr Rev 2007;65:39-45.

2. Kay CD, Gebauer SK, West SG, et al: Pistachios increase serum antioxidants and lower serum oxidized-LDL in hypercholesterolemic adults. J Nutr 2010;140:1093-1098.

3. Kocyigit A, Koylu AA, Keles H: Effects of pistachio nuts consumption on plasma lipid profile and oxidative status in healthy volunteers. Nutrition, metabolism, and cardiovascular diseases : NMCD 2006;16:202-209.

4. Sari I, Baltaci Y, Bagci C, et al: Effect of pistachio diet on lipid parameters, endothelial function, inflammation, and oxidative status: a prospective study. Nutrition 2010;26:399-404.

5. Aldemir M, Okulu E, Neselioglu S, et al: Pistachio diet improves erectile function parameters and serum lipid profiles in patients with erectile dysfunction. Int J Impot Res 2011;23:32-38.