A prostate biopsy is the only definitive way for your doctor to confirm whether you have prostate cancer. Once you and your doctor have decided that a prostate biopsy should be performed, a post-biopsy follow-up clinic visit will be scheduled to discuss the results. If there is no cancer, your doctor will talk with you about follow-up appointments. These include follow-up PSA blood tests and possibly prostate MRI imaging. If there is prostate cancer on the biopsy, your doctor may recommend treatment. Treatment recommendations may include a radical prostatectomy (surgery to remove the prostate gland), radiation therapy, or active monitoring (also called active surveillance).
Your doctor’s recommendation will depend on many factors including PSA at the time of biopsy, Gleason score, and your overall health. In certain situations, it may be helpful to understand more about your prostate cancer to help guide treatment strategies.
One such strategy is the use of biomarkers in the post-prostate biopsy setting. Biomarkers are special molecules found in blood or tissue that can help your doctor find out if you have cancer or not. They help to further clarify risk. The risks may include:
- Prostate cancer in the prostate gland even after a negative biopsy
- Tumor aggressiveness
- Recurrence after treatment, etc.
In prostate cancer, biomarkers in the post-biopsy setting are tests that are done on the prostate tissue removed during the biopsy, and in some situations on the whole prostate gland after a radical prostatectomy. The following list represents the available biomarkers that may be used to guide further monitoring and/or treatment after a prostate biopsy has been performed:
- ConfirmMDx: For men who have previously had a negative (no cancer) prostate biopsy, this biomarker can test the tissue from the first biopsy to check for changes that may suggest prostate cancer in other areas of the prostate that were not biopsied. This process is called “epigenetic changes,” which assesses for hypermethylation of GSPT1, APC, and RASSF1.
- Prolaris: This test measures tumor biology (providing a cell-cycle progression score) that improves the accuracy of risk stratification for men that have been diagnosed with localized prostate cancer. Specifically, this test combines the RNA (part of your genetic material) expression levels of 31 genes involved in prostate cancer progression + 15 other “housekeeping” genes to generate the Prolaris Score. The Prolaris test has been used to guide doctors and patients as to who may be an appropriate candidate for active surveillance, as well as those that should receive definitive treatment.
- Oncotype Dx: Also known as the OncotypeDx Genomic Prostate Score , OncotypeDx improves risk stratification in men with newly diagnosed prostate cancer. This test utilizes RNA expression levels of 12 prostate cancer genes and 5 reference genes to generate the GPS (scale of 0 to 100). Additionally, when this test is used on the whole prostate gland after a radical prostatectomy, OncotypeDx provides a risk of biochemical recurrence (PSA increasing in the blood) after the prostate is removed among men with low and intermediate-risk prostate cancer.
- ProMark: Among men with Gleason 3 + 3 and Gleason 3 + 4 prostate cancer on a prostate biopsy, this biomarker is a protein-based test that predicts the aggressiveness of a patient’s cancer. ProMark uses a “signature” of 8 proteins to provide a score of 0 to 1. It also predicts the risk of adverse pathology (high-risk disease) at the time of radical prostatectomy.
- Decipher: Arguably the biomarker with the most robust evidence is the Decipher genomic classifier, which measures RNA expression of 22 different genes. Similar to OncotypeDx and ProMark, Decipher is available for testing on prostate biopsy tissue and radical prostatectomy whole prostate specimens. Of note, Decipher is specifically mentioned in the National Cancer Comprehensive Network (NCCN) guidelines as an approved biomarker for risk stratification. In addition to being useful for local therapy planning for newly diagnosed localized prostate cancer patients, Decipher provides several important pieces of information among patients who have had a radical prostatectomy:
- Likelihood/timing of post-radical prostatectomy salvage radiation therapy
- Predicting clinical metastases (disease spreading outside of the prostate bed after surgery) for patients with biochemical recurrence after surgery
- Likelihood of clinical metastases within 5 and 10 years after radical prostatectomy for men with high-risk pathology after surgery
Deciding whether to utilize one or more of these biomarkers after a prostate biopsy (or after a radical prostatectomy) to help determine surveillance intensity and other treatment decisions should be discussed in a shared decision-making approach between you and your doctor. In many cases, biomarkers will not be needed to make the right decisions. However, in some cases, this additional information may be valuable. There may be enough evidence that primary therapy (after a prostate biopsy) or salvage therapy (after primary therapy has failed) is needed even without a biomarker test. It is important to realize that all of these biomarkers may not be available at your doctor’s institution or may not be covered by your insurance, leading to out-of-pocket costs.