The finger exam, also known as a prostate exam or, more formally, the digital rectal exam (DRE) is a worry of men over the age of 50 going in to see their primary care doctor.  But do patients need to be afraid?  For many years, this exam has been a mainstay in a doctor’s arsenal for detecting nodules that may indicate prostate cancer; but is it accurate?  

In one UK study, patients with a normal prostate exam still had a 16% risk that a cancer was still present.   In one meta-analysis, DRE performed by primary care clinicians had an estimated sensitivity and specificity near 50%.  This means that approximately half of all abnormal rectal exams were “false positives.”  A false positive is a result that erroneously suggests disease.  False-positive results could lead to anxiety, needless biopsies and more with potential complications such as bleeding, infection, incontinence and erectile dysfunction.  What is the solution?

The digital rectal exam in primary care has largely been replaced by a test for prostate specific antigen or PSA.  This is a protein in the blood that is produced by prostate tissue and is elevated by the presence of cancer.  This is also an imperfect test as there is no specific PSA level that diagnoses prostate cancer.  It is only known that very high PSA values suggest the cancer’s presence.  Unfortunately, PSA levels can also be increased by prostatic infection or even mild trauma, and such “false” high readings can cause unnecessary concern about cancer and even unnecessary surgery.  

A more appropriate testing platform would be to identify at-risk patients and then establish a baseline for each patient on which to evaluate the marker over time.  Large increases compared to previous numbers are more worrisome than high results alone.  

Who are the at-risk patients?  Age is the most important factor with the highest incidence being in men over 80 years old though PSA screening is discouraged for men with less than a 10-15 year life expectancy.  African American men are also at increased risk.  Those with first degree relatives diagnosed with prostate cancer or relatives with mutations of the BRCA1/2 genes are also at an elevated risk.  

Certain symptoms in a patient can also guide a physician’s thoughts about an individual patient’s need for DRE or PSA screening.  These include low back pain, blood in urine, weakness in the legs, incontinence or the inability to void.

So is the “finger exam” out?  Not necessarily; it is useful in patients with bloody stool or other rectal problems.  Further, an abnormal DRE might catch a prostate cancer that otherwise might have been missed, so what’s the answer?  The United States Preventative Service Task force recommends an individualized approach to screening where the risks and benefits of screening, DRE and PSA, are discussed with each patient considering their age, race, genetics, and other factors.  This means it is between the patient and his doctor to decide the best approach for that patient.  At any suggestion of the presence of cancer, the primary care physician will refer the patient for further evaluation and treatment.