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Should You Get Screened for Prostate Cancer?

PROSTATE_CANCER

Part of my annual physicals with patients is reviewing a health maintenance checklist.  I verify that they are up-to date with age-appropriate vaccines, cancer screening tests, and other preventative measures.  For men over age 50, we discuss whether to screen for prostate cancer.  At first, it may seem like a no-brainer to screen for any kind of cancer.  But with prostate cancer, the decision whether or not to screen is not so straightforward.  In this post, I’ll provide some basic information about prostate cancer that I hope will be helpful.

What is the prostate?

It is a gland that sits below the bladder and in front of the rectum.  It forms a ring around the urethra, the tube takes urine out of the body.   The prostate gland’s function is to secrete fluid that takes sperm out of the body.

What is prostate cancer?

In prostate cancer, the cells of the prostate become abnormal and grow out of control.  Prostate cancer can spread to other parts of the body and ultimately cause death.

When should I be concerned that I might have prostate cancer?

It becomes more common as men age, most prevalent in men over age 50. Some symptoms of prostate cancer are needing to urinate more frequently and having a urine stream that is slower than usual.  However, these symptoms can be from other health conditions such as having an enlarged prostate.

How do doctors test for prostate cancer.

There are two initial tests. The first is the rectal exam in which the doctor puts their finger in the rectum and presses on the rectal wall to feel for abnormal areas on the prostate. The second is the PSA blood test. PSA can be high for other reasons besides prostate cancer.  For example, having a big prostate, having a prostate infection, and having recently had sex can all make the PSA high.  So if the PSA is high, it is usually repeated to see if it stays high.

If the PSA or rectal exam suggests cancer, what comes next?

Usually a urologist performs a biopsy of the prostate in which they get tissue from the prostate to be examined under the microscope.

What are reasons why I should get screened for prostate cancer?

One large European study showed that after 9 years, men who had done PSA testing had a 20% lower chance of dying of prostate cancer.  34,000 men die each year of prostate cancer and it can be a painful death.  It is second only to lung cancer in causing cancer-related deaths in men.  For men with aggressive prostate cancer, the best way of curing it and preventing death is catching it early by doing the PSA test.  If prostate cancer is caught early, the cure rate is nearly 100%

So why wouldn’t you want to get tested for prostate cancer?

Many prostate cancers detected with screening are unlikely to cause death.  These cancers would never have spread beyond the prostate and have harmed the man.  One European trial says that you have to treat 50 men with prostate cancer that was never going to bother them in order to prevent one death from prostate cancer.  Treating non-aggressive prostate cancers can cause frequently serious problems like impotence and incontinence.  In fact, roughly half of all men who receive radiation or surgery have incontinence and impotence.  So many men are receiving a harmful treatment for little benefit.

Once a prostate biopsy is done, can doctors predict if they prostate cancer will be aggressive and life-threatening?

The PSA score, the way the prostate cancer looks under the microscope (Gleason score), and how far is has spread help predict how threatening the cancer will be.

Bottom Line

Men must weight the potential benefits of screening against the potential harms.  One strategy is to screen for prostate cancer only in men with an increased risk of aggressive prostate cancer, such as men of African ancestry and those with a family history of prostate cancer.  Another approach is to broadly screen for prostate cancer, but closely monitor, rather than treat men with prostate cancer that is not aggressive.  In my conversations with patients, we discuss the pros and cons of prostate cancer screening and do our best to arrive at a decision together.

 
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Posted by on August 20, 2013 in prostate cancer

 

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Do Omega-3 fatty acids cause prostate cancer?

Do Omega-3 fatty acids cause prostate cancer?

Omega-3 fatty acids have long been one of the most commonly used medical supplements.  In the 1970s, researchers studying the Greenland Intuit Tribe noted that while they consumed large amounts of fat from fish, they displayed virtually no cardiovascular disease.  This finding was attributed to the high amount of omega-3 fatty acids in their fish-rich diet.

The main reason I prescribe omega-3 fatty acids is to lower triglycerides, a type of bad cholesterol that can inflame the pancreas if their level in the blood gets too high.  But omega-3s are taken to treat many other conditions, including dry eyes, depression, and attention deficit disorder (ADD).  The evidence of their efficacy for these other indications is not robust.  But since Omega-3s occur in nature and are not thought to have many serious side effects (aside from possibly fishy breath!), many doctors and patients ask themselves “why not try them?”  Many people take Omega-3s not for any specific reason, but as a general measure to maintain good health.  Such an attitude seemed validated by a 2010 study published in the Journal of the American Medical Association (JAMA) which showed that people with a higher concentration of omega-fatty acids in their blood seemed to be aging slower. The ends of chromosomes, called telomeres, are shortened with aging.  The telomeres in people with higher serum levels of omega-3s were shortening at a slower rate than others.’

With all this omega-enthusiasm, it came as a surprise when a recent study in the Journal of the National Cancer Institute suggested a possible downside to the fishy pills.  Studying men over age 50, it found that those with the highest levels of omega-3 fatty acids in the serum had a 43% higher risk of developing prostate cancer, and a 71% higher chance of developing high-grade prostate cancer, which is more likely to be fatal.  The study did not examine whether the men with higher omega-3 levels had them due to supplements or their diet.

Does this mean Omega-3s cause prostate cancer?  Not necessarily.  We would need a different kind of study to answer this question.  One possible partial explanation for the association between prostate cancer and higher omega- 3 levels is that men who ingest more omega-3 fatty acids may be the kind of guys who get regular check-ups and are screened for prostate cancer.  More prostate cancer was detected in men with higher omega-3 levels, but maybe men with lower levels had prostate cancer that was never screened for and detected. A similar kind of study bias accounts for why taking hormone replacement therapy was long associated with a reduced risk of coronary artery disease in women after menopause.  It turned out that women receiving hormone replacement therapy were more likely to being seeing their doctor and taking other steps (exercising, eating healthy, controlling blood pressure) that reduce heart disease risk.  It was not until a later prospective, interventional trial (the Women’s Health Initiative) that we came to see that taking hormone replacement therapy actually increases the risk of coronary artery disease.   We would need a similar type of study to see if ingesting more omega-3 fatty acids really increases men’s risk of developing prostate cancer.

One important take-away from this study is that nutritional supplements are not always as safe as they seem.  It is wise to have a specific reason for taking a supplement that is supported by strong scientific evidence.

 
 
 
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