Understanding Your Results
Treatment plans for prostate cancer patients are most effective when based on an individual’s specific grade and stage of cancer as determined by laboratory test results. At our institution, we combine many factors in addition to a patient’s PSA test results and Gleason score (determined by biopsy and pathological examination) to design and implement the best treatment available.
For the layperson, this information can at times be overwhelming. But we provide a comprehensive overview to help educate you about the various tools available for the diagnosis and treatment of prostate cancer. An understanding of these tools can be very helpful in making a decision about your treatment options.
1. The PSA and DRE tests
The PSA is a blood test that measures the amount of prostate specific antigen (PSA) present in the body. Produced almost exclusively by the prostate gland, PSA is an enzyme typically present in only minute quantities, secreted into the bloodstream from blood vessels inside the prostate. When prostate cancer is present, additional PSA is usually produced. This extra PSA can be detected and measured in the blood through a simple lab test.
Because cancerous cells readily leak PSA into the surrounding body tissue, an elevated PSA is a possible indicator of the presence of prostate cancer. However, other conditions can also cause an elevated PSA. The most common is benign prostatic hyperplasia (BPH), the enlargement of the prostate gland that often occurs with aging. Infections and traumas such as a biopsy or even an overly vigorous digital rectal exam can also sometimes increase PSA levels. Ejaculation (orgasm) can elevate PSA for as long as 48 hours.
Though the PSA test is far from perfect as an indicator of cancer, the American Cancer Society (ACS) suggests that starting at age 50, men should talk to their doctors about the pros and cons of testing so they can decide if testing is the right choice for them. The ACS guidelines also suggest testing may be advisable for men who are considered at higher risk (such as African-American males and those men with a family history of prostate cancer) starting at age 45. For men with even higher risk, such as those with several first-degree relatives who were diagnosed with prostate cancer at an early age, initial testing might be considered by age 40.
The PSA is presently the most sensitive tumor marker for the identification and monitoring of prostate cancer, but as a diagnostic tool, the PSA test has its limitations, and it is usually combined with the digital rectal examination (DRE). Some men with apparently normal PSA values turn out to have prostate cancer that may be detected with the DRE or by other lab tests.
The digital rectal exam is the simplest way to detect physical abnormalities in the prostate gland that may suggest the presence of cancer. To perform the rectal exam, the doctor feels the gland by placing a lubricated, gloved finger inside the rectum against the prostate. When done properly, the test is not as discomforting as it might sound. Most cancers are located in the back of the prostate, and some of these cancers that have grown at the edge of the gland can be felt as a lump or hard nodule. Unfortunately, the DRE is often not conclusive. Many prostate cancers do not protrude against the back of the gland; they are not palpable and cannot be detected with the DRE
The DRE is also used to estimate the volume of the prostate and the extent of the cancer. The DRE and PSA tests are part of the physician’s work-up, which involves a series of laboratory and radiographic tests that are used to determine how advanced and how aggressive the cancer is. The results of these tests, including the Gleason score, will be evaluated to determine the clinical stage of the cancer, and they are also used to decide which type of treatment is most appropriate for your particular cancer.
2. The Prostate Biopsy and Gleason score
A prostate biopsy is a procedure by which samples of tissue are removed from suspicious areas of the prostate gland for microscopic examination by a pathologist. A biopsy is absolutely necessary to confirm the presence of cancer and should be undertaken prior to any treatment of the disease. The biopsy also provides physicians with a wealth of information about the specific characteristics of the cancer. A pathologist will evaluate the biopsy samples under the microscope to determine the Gleason score.
The Gleason score is a widely used method for classifying the cellular differentiation of cancerous tissue in order to determine how aggressive the cancer is. The less the cancerous cells appear like normal cells to a pathologist, the more malignant the cancer is likely to be. Two grades of 1 to 5, which identify the two most common degrees of differentiation in biopsy tissue samples, are added together to produce the Gleason score, which can range from 2 to 10. Higher Gleason numbers indicate greater differentiation and more aggressive cancer.
3. The PAP test
At our center, a PAP (Prostatic Acid Phosphatase) blood test is also routinely performed, as this test has been demonstrated by our team and other researchers to be perhaps the most adverse feature associated with prostate cancer. An elevated PAP (3.0 or higher) in many patients suggests the cancer has spread outside the prostate. When cancer has spread outside the prostate, it is unlikely to be effectively treated by surgical removal of the gland, and is more readily eradicated by radiation therapy.
4. Identifying and treating cancer outside the prostate
In the field of nanotechnology, the USPIO (Ultra-Small Super-Paramagnetic Iron Oxide) imaging test involves an intravenous infusion of radioactive nanoparticles such as Ferumoxytol (Feraheme), which makes it possible for us to obtain a very revealing picture of exactly where active prostate cancer cells have traveled through the lymph system outside the prostate. We have been blazing a trail for lymphatic node identification and subsequent radiation therapy in partnership with radiologist Dr. Stephen Bravo and his colleagues at Sand Lake Imaging in Orlando, Florida.
This USPIO technique and other advanced imaging tests help us detect possible sites of metastatic and recurrent prostate cancer that more conventional tests can’t identify. Locating recurrent prostate cancer allows us to identify small, isolated deposits of cancer—both within and outside the prostate—that can be targeted for more effective treatment. This is indeed good news for those men who after primary treatment experience an otherwise unexplained rise in PSA that suggests recurrent cancer.
Our state-of-the-art imaging techniques can identify lymph node spread in patients initially treated for high-risk disease, and they are already allowing us to effectively treat patients with positive lymph nodes by utilizing DART (Dynamic Adaptive Radiotherapy). Our expectation is to further increase our cure rate in this group of patients by treating lymph nodes which may otherwise have not been detected and located with specificity without the benefit of the USPIO/MRI scanning and/or contrast-enhanced MRI and CT imaging. This is perhaps the most exciting research being performed at our center and we believe will result in a paradigm shift in how more advanced prostate cancer is treated.