The PSA blood test and Digital Rectal Exam (DRE) can be used to detect the presence of prostate cancer when no symptoms are present. They can help catch the disease at an early stage when treatment is thought to be more effective and potentially has fewer side effects.
During a DRE, the physician inserts a gloved, lubricated finger into the rectum and examines the prostate for any irregularities in size, shape, and texture.
During a PSA test, a small amount of blood is drawn from the arm, and the level of PSA, a protein produced by the prostate, is measured. PSA levels under 3 ng/mL are usually considered “normal”. A normal PSA however must take into account a patients age, their prostate size, and other conditions present such as BPH or prostatitis.
It is important to note that some men with prostate cancer can have “low” levels of PSA naturally, and some medicines can artificially lower your PSA such as finasteride, dutesteride, or even saw palmetto.
Making the Diagnosis
Although a high PSA make increase a Doctor’s suspicion for prostate cancer, an elevated PSA alone does not confirm a true diagnosis of prostate cancer. The way prostate cancer is diagnosed is with a prostate biopsy. There are three main ways men are diagnosed with prostate cancer:
- TRUS-guided biopsy: This is a trans-rectal ultrasound guided biopsy. An ultrasound in placed in the rectum to allow visualization of the prostate and then 6-14 needs are placed into specific areas of the prostate to sample for cancer. This is the most common way prostate cancer is diagnosed.
- Trans-perineal biopsy: In select men who can’t have a trans-rectal biopsy, they can be biopsied by placing needle through the skin called your perineum (skin between the scrotum and anus).
- Incidentally: Some men are diagnosed accidently as they were having an unrelated procedure done to their prostate (a TURP) or bladder, and prostate cancer was found.
Regardless of how the diagnosis is made, the prostate tissue obtained is then examined under a microscope by a pathologist to confirm the presence or absence of prostate cancer.
Research is ongoing with using targeted or fusion-biopsies using an MRI in addition to the ultrasound to better visualize the prostate and tumors within the prostate to help guide the biopsy needles.
Staging your Disease
There are 4 main components to staging prostate cancer:
- Your PSA level
- Doing a biopsy to find out the “grade” of your cancer
- Determining if the prostate cancer is contained completely within the prostate
- For select men, getting imaging to determine if the cancer has spread to lymph nodes or bones.
PSA: Is simply a standard blood test. Your Doctor should have your most recent PSA tests, and if outdated, they may order a fresh one.
Grade: How aggressive the cancer looks under the microscope.
- During a trans-rectal biopsy, needles are inserted into the prostate to take small samples of tissue (usually 6-14 biopsies). If prostate cancer is found when looking at the biopsied tissue under the microscope, the pathologist assigns a grade to the cancer.
- The grading system used to be called the Gleason score, which had a scale of 2-10. If you had cancer you were given a Gleason score of 6-10; 6 was low grade, 7 was intermediate grade, and 8-10 was high grade.
- The Gleason score has recently been replaced by a simpler system simply called “grade groups”. There are 5 grade groups on a scale of 1 to 5. Low grade is 1, and very high grade is 5.
Tumor stage (or T-stage): Staging determines the extent of prostate cancer and provides an idea of how the cancer should be treated. To tumor the extent of the cancer within the prostate this is imperfectly done with the digital rectal exam (DRE). In select cases your Doctor may order a prostate MRI to help determine if the cancer is confined to the prostate.
- T1- The tumor was found solely because of an elevated PSA or incidentally during a procedure on the prostate or bladder.
- T2- The Doctor could feel a nodule(s) on your prostate during the rectal exam.
- T3- The tumor extends out of the prostate capsule
- T4- The tumor invades into the rectum or bladder. This is uncommon and very advanced.
Evaluating for metastatic disease: In men with aggressive features (e.g. PSA >20, high grade or tumor that may be extending out of the prostate) usually warrant imaging to rule out the presence of metastatic disease. This is most commonly with a CT scan and a bone scan. Prostate cancer when it is advanced can spread to lymph nodes and/or bones, and this important for your Doctor to know as this will impact their treatment recommendations.