Effective cancer screening methods are used to detect or identify the presence of a specific cancer before the individual displays any symptoms of cancer. Early detection of a cancer through screening can save the life of a person who may have died without screening detection. Early detection of cancer can also provide a less costly and more effective treatment than if the cancer progresses requiring more advanced or drastic treatment. Screenings tests for the more common cancers such as breast, colon, prostate or cervical can be non-invasive or only slightly invasive. The majority of screening procedures are non-invasive which is more cost effective, patient convenient, and does not require any patient aftercare. Screening tests usually have a recommended age and frequency. As people age there is a higher risk of cancer and more screening is recommended. There are some considerations on whether to screen or not to screen such as; is the cancer common or fatal, are there detectable symptoms, and how reliable are the test results.
There are currently two slightly invasive screening tests used to detect prostate cancer. They are the digital rectal exam (DRE) and the prostate-specific antigen blood test (PSA). The DRE is a quick exam that can check the prostates health. A doctor inserts a gloved and lubricated finger into the rectum to feel the back portion of the prostate for size, irregularity or abnormal areas (www.cancer.gov, 2012). DRE is the only method in which a physician can physically examine the prostate gland. If a doctor does find an irregularity the conclusion is not necessarily prostate cancer, but a reason to pursue diagnosis.
“Prostate-specific antigen (PSA) is a protein produced by cells of the prostate gland” (National Cancer Institute, 2009). A laboratory will perform a PSA test to measure the amount of PSA in a patient provided blood sample. PSA levels can be compared against prior PSA test levels for changes. The PSA test is an excellent screening tool because it is highly sensitive, reasonably priced, and well-tolerated by patients. A PSA level alone is doesn’t distinguish what could be benign prostate conditions or cancer. A doctor considers PSA test when deciding whether to check further for signs of prostate cancer (National Cancer Institute, 2009).
There are difficulties and controversy associated with the current screening methods for prostate cancer. The PSA test for prostate cancer has become controversial as it is “not yet known for certain if this test actually does saves lives. It is not clear if the benefits of PSA screening outweigh the risks of diagnostic tests and cancer treatments” (National Cancer Institute, 2009). According to NCI, a PSA test may detect a small amount of cancer that may never become life threatening. This is referred to as over diagnosis and this can put men at risk of complications from any additional and unnecessary treatment (National Cancer Institute, 2009).
A study at the Washington University found 25 to 35 percent of men who had a lower than normal PSA level and underwent a prostate biopsy were found to have prostate cancer. That means that 65 to 75 percent of the remaining men did not have prostate cancer. This concludes that there is no exact specific normal or abnormal PSA levels (National Cancer Institute, 2009).
A DRE screening may be done as part of a routine medical examination or if there are symptoms like rectal bleeding, urethral bleeding or discharge, bowel habit changes, or changes in the urinary stream. In the early stages of prostate cancer a tumor may be non-palpable, which means the tumor is not detected by touch. This may be due to the tumor being small and in the early stage of prostate cancer or it can be located in areas where a doctor’s finger can’t touch or reach. Although the DRE is a useful test, it isn’t foolproof. The test accuracy is dependent on the skills of a physician to conduct and interpret the test. Therefore the DRE test alone to screen for prostate cancer can sometimes miss the small and treatable tumors (National Cancer Institute, 2009).
One future cancer screening test for prostate cancer is called EPCA -2 testing. “EPCA (early prostate cancer antigen) is a protein that is present in the blood in higher amounts in men who have prostate cancer than in men without cancer” (Prostate.net, n.d.). A 2007 article, according to Prostate.net, published in the journal Urology provided evidence that EPCA-2 testing was more cancer specific than PSA. If this is true, the test “could reduce unnecessary biopsies and the over diagnosis and over treatment of prostate cancer” (Prostate.net, n.d.). As of 2009 EPCA-2 research is continuing (Prostate.net, n.d.).
The PCA3 assay prostate cancer test is being conducted in Europe. This test detects the amount of a gene called PCA3 in urine. Research show that this gene could be an indicator for prostate cancer as it is “highly evident in most men who have prostate cancer” (Prostate.net, n.d.). In preliminary data according to Prostate.net, the PCA3 test has shown to be more specific in detecting prostate cancer than the PSA test. PCA3 assay is still being tested in the United States and as of May 2010 the FDA has not granted marketing approval (Prostate.net, n.d.).
Future cancer screening includes a blood test currently being studied in several facilities, including the Dana-Farber Cancer Institute in Boston, which can identify among a billion healthy cells one single cancer cell. “The blood test uses a microchip that looks like a lab slide covered in 78,000 minute posts coated with antibodies that bind to tumor cells. When blood passes across the chip, cancer cells stick and stains make them glow for easy detection” (Prostate.net, n.d.). This blood test could possibly eliminate tissue sampling and imaging scans (Prostate.net, n.d.). EN2 is a new prostate cancer test measuring the EN2 protein in urine. “The study found that testing for the protein could accurately identify 66% of men with prostate cancer, and correctly rule out the disease in almost 90% of men without the disease” (National Health Service, 2011). The cases of prostate cancer were confirmed with a biopsy. The University of Surrey, UK studies confirmed that “even if the EN2 test performs well in larger scale testing, the test would not necessarily replace PSA testing” (National Health Service, 2011) but could be used with PSA (National Health Service, 2011)