Prostate Cancer, Digital Rectal Exams, PSA and Screening

The PSA blood test, to detect prostate cancer, clearly has saved lives according to numerous studies. The United States Preventive Task Force (USPTF) recognizes this but has decided that screening for prostate cancer is not a great idea in men aged 55-69. They point out the PSA can be elevated from an enlarged prostate, an inflamed or infected prostate, a recent orgasm while having sex and other causes.

Elevated PSAs led to trans-rectal ultrasound views of the prostate and biopsies of the prostate. These biopsies were uncomfortable, even painful, and often followed by inflammation and infection of the prostate. Many times the prostate biopsy was benign with no cancer detected. The USPTF felt the cost, worry, and potential side effects were a risk far outweighing the benefits of screening. They consequently came out against screening men in this age group.  Naturally this position produced a tidal wave of criticism from urologists and other.

So, the USPTF has produced new recommendations calling for patient education and making a shared decision whether or not to obtain a PSA measurement before you send it out. This is a bit confusing because we always discuss the pros and cons of a PSA before we draw it. Adult men are entitled to hear the pros and cons so they can make their own informed decision.

To complicate matters, a study out of McMaster University in Canada reveals physicians are poorly trained in performing a digital rectal exam. They cite the lack of experience coming out of school and going into training and cite numerous research studies showing a rectal exam is a low yield way to detect prostate cancer. They do not recommend performing digital rectal exams for prostate cancer screening.

This received much media hype and the blur between the efficiency of detecting prostate cancer via a rectal exam and the use of the rectal exam to detect rectal and colon disease has been lost. We perform digital rectal exams to detect prostate cancer and look at the perirectal area for disease. We test the strength and performance of the anal sphincter muscle. We feel for rectal polyps and growths and, in certain situations, test the stool for the presence of blood.

During my internal medicine training my teachers always required a digital rectal exam, stool blood test and slide of the stool as part of the exam. As trainees, we realized the invasiveness of the exam and did our best to be polite, gentle and caring. I always asked for permission first, and still do. How can you tell if something is abnormal if you haven’t performed normal exams?

Last but not least, Finesteride, a medicine used to shrink an enlarged prostate by inhibiting male hormones, has finally been shown to be protective against developing prostate cancer. A study published in the journal of the National Cancer Institute found that men taking it for 16 years had a 21 % lower incidence of prostate cancer.

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MRI Use in the Detection of Prostate Cancer

As men live longer the likelihood of them developing prostate cancer increases. Some experts estimate that if we biopsied the prostate of every male 80 years old or older, we probably would find prostate cancer present in almost all of them.

The PSA test has been shown to be less valuable than previously thought when discovered because it does not distinguish between an elevated level due to normal prostatic enlargement, infection or the presence of cancer.  When it is elevated due to cancer it cannot predict which tumors are aggressive and require aggressive treatment and which tumors are non-aggressive or indolent and can just be watched.  For this reason, CMS or Medicare and the United States Preventive Task Force are opposed to PSA use as a screening test.

To deal with these issues, Robert K. Nam MD, MSc, chairperson of genitourinary oncology and professor of surgery at Sunnybrook-Health Sciences Centre in Toronto, Canada has published a small preliminary study in the Journal of Urology on the use of MRI (magnetic resonance imaging) to predict the presence of and the aggressive status of prostate cancer disease.

They recruited men who knew they would be undergoing a PSA test, a MRI of the prostate and a prostate biopsy. Their preliminary results show that the MRI was a better predictor of the presence of prostate cancer than the PSA.  It was also felt to identify how aggressive the disease was which influenced treatment options offered. It was additionally felt to be very accurate in identifying when no prostate cancer was present.

Small numbers of patients were entered in this pilot study. A larger randomized controlled study is now in the planning stages to further clarify these initial findings.  At the same time in our community some of the urologists are now ordering MRI scans to elucidate what is causing an elevated PSA in individuals who have a non-diagnostic digital rectal exam and an elevating PSA.

Prostate Cancer: Progress in Detection and Treatment

Until recently, prostate cancer was considered by many to be a disease of “old men” only.  As a result, science for the detection and treatment of prostate cancer was lagging decades behind that of breast cancer.  In fact, it was commonly believed that if doctors performed a biopsy on the prostate of all men eighty years old or older, at the time of their death from non-prostate related issues, we could expect to find evidence of undetected prostate cancer in close to 100% of those patients.

The discovery and use of the PSA (Prostate Specific Antigen) led to detection of prostate cancer in younger men. The PSA test was fairly inexact and could become elevated as a result of any of several non-cancerous conditions. It led to numerous biopsies in men who had no clinical findings consistent with prostate cancer but who turned out to have the disease. These young men were treated aggressively, and at times the treatment was as bad if not worse than the disease. The problem was that when we found a prostate cancer we had no idea if it was destined to be aggressive or whether it was going to lie quietly and be indolent for decades.

Different treatment strategies emerged in Europe and the United States.  In Europe the PCA3 test was employed to detect genetic markers of men with elevated PSA’s and normal prostate gland examination who should be biopsied. This test is now gaining acceptance in the USA.

In a February 2011 article published in Nature magazine, researchers announced that they had found a genetic test for prostate cancer  samples that predicted whether the disease would be aggressive (and spread) or not. This new test, coupled with the existing Gleason scoring system, accurately predicted who needed to be treated aggressively and who could be watched instead. A commercial version of this genetic test should be available within two years.  At the same time, another article showed that in patients with minimal prostate cancerous disease, it is safe to observe them rather than aggressively operate on them immediately.

Health experts recommend all men 40 and over have a digital rectal exam on an annual basis. The decision to obtain a PSA is based on history, family history of prostate disease and clinical exam of the prostate. There are no current recommendations by the US Public Health Task Force on Preventive care for screening for prostate cancer with a PSA level. Despite this, I generally obtain a PSA annually on men over 50 after explaining to them the pros and cons of following the current guidelines.

If the new genetic test to predict prostate cancer aggressiveness turns out to be as accurate as suspected, we are finally on the road to being able to treat those who need aggressive treatment and spare others who don’t.