How is prostate cancer diagnosed?
Prostate cancer is diagnosed with a TRUS-guided biopsy. A TRUS-guided biopsy is triggered when patients have a positive screening test (usually an elevated PSA or abnormal digital rectal examination). This is further discussed on the Screening for Prostate Cancer page. In rare circumstances, prostate cancer is detected in men who are experiencing symptoms of prostate cancer or incidentally after a Transurethral Resection of the Prostate for Benign Prostatic Hyperplasia (BPH).
What are symptoms of prostate cancer?
Prostate cancer can rarely present with urinary symptoms related to its local effect in the prostate gland. Rarely, prostate cancer can also present with symptoms from metastases (tumor that has spread to other parts of the body). Symptoms of metastatic prostate cancer include fatigue, bone pain, fractures, and neurologic symptoms.
What is a TRUS-guided Biopsy?
TRUS-guided biopsy stands for transrectal ultrasound guided biopsy. This is the usual technique by which prostate cancer is confirmed.
A TRUS-guided biopsy involves the use of a transrectal ultrasound probe to systematically biopsy the prostate gland. The basic procedure is as follows:
- Patients on blood thinners have to discuss a plan for these blood thinners around the time of the biopsy procedure with Dr. Matsumoto and/or relevant specialists. The process of stopping certain blood thinners may begin a week or more before the procedure.
- Patients begin their antibiotic regimen the day before the procedure–usually 3-days worth of antibiotics are prescribed for the day prior, the day of, and the day following, the biopsy.
- Patients should perform an enema 6-12 hours before the biopsy procedure. This clears the rectum of stool and can aid in visualization during the procedure.
- The biopsy itself is performed in the radiology suite. For biopsies at St. Joseph’s Hospital, this is on Level 0 of the Juravinski tower.
- Patients are instructed to lie on their side and flex their knees and hips.
- A rectal examination is performed, following which a small lubricated ultrasound probe is inserted into the rectum. This process is similar to having a digital rectal examination.
- Ultrasound images are acquired of the prostate gland, and local anesthetic is injected into the region of the nerves surrounding the prostate.
- 10-14 biopsy cores are taken from the prostate with a biopsy gun. Most patients do not feel much of the biopsy process due to the local anesthetic. The biopsy gun clicks loudly as it fires which may be startling.
- Another rectal examination is performed and the procedure is terminated.
What are the complications related to a TRUS-guided biopsy?
While most patients will tolerate a TRUS-guided biopsy well, a minority will develop complications related to the procedure. These include:
- Discomfort. Most patients tolerate the procedure well but some may have significant discomfort from the probe and/or biopsy procedure itself.
- Infection. Developing a serious infection requiring hospitalization may arise in 2-4% of patients. Patients are advised to seek medical attention promptly if they have fevers or feel unwell after their biopsy procedure.
- Bleeding. Blood in the stool, semen, and urine is common after the procedure. This usually resolves in the days to weeks following the biopsy. Blood in the semen can last for months and is not harmful.
Other rare complications have been reported but discomfort, infection and bleeding are the main ones to be aware of.
What is staging?
Staging is a description of the extent of prostate cancer present in the body. A lesser stage of cancer suggests that less disease is present and has a better prognosis. Staging helps physicians to decide on the best treatment for each individual patient, balancing the chance the therapy would have to cure prostate cancer at that stage with its impact on quality of life.
Several broad staging categories are possible:
Localized prostate cancer – a prostate cancer that is contained within the prostate. Options for managing localized prostate cancer include active surveillance, surgery, and radiation therapy. In more technical terms, localized prostate cancer includes T1-2 tumors or clinical stage I-II.
Locally-advanced prostate cancer – a prostate cancer that is still within the region of the prostate but is starting to invade the tissues surrounding the prostate. This usually involves invasion of areas of fat around the prostate, but can also include involvement of the seminal vesicles, bladder, rectum, and pelvic floor muscles. Options for managing locally-advanced prostate cancer include surgery or radiation therapy. Locally-advanced prostate cancer is curable in some patients. In more technical terms, locally-advanced prostate cancer includes T3-T4 tumors or clinical stage III and some clinical stage IV patients.
Metastatic prostate cancer – prostate cancer that has spread away from the local area of the prostate. Usual sites of spread include the lymph nodes or bones. Prostate cancer can rarely also spread to other organs. Metastatic prostate cancer is initially managed with hormonal therapy. Chemotherapy is also given to some patients. Metastatic prostate cancer is not curable, but can be controlled for long periods of time in most patients. In more technical terms, metastatic prostate cancer includes N1 or M1 patients and most patients with clinical stage IV.
What is the Gleason score?
The Gleason score refers to an impression of how aggressive the prostate cancer looks under the microscope. A lower Gleason score correlates with a lesser stage and better prognosis. In combination with the cancer’s stage and PSA level, the Gleason score is an important part of deciding what treatment is most appropriate for individual patients.
Gleason scores usually range from 6 to 10.
Gleason 6 – This is the lowest score usually assigned. Many patients with a small amount of Gleason 6 disease can be safely watched in an active surveillance protocol. A good proportion of patients with a low volume of Gleason 6 cancer will never be bothered by this tumor which tends not to be aggressive. Patients with Gleason 6 disease that do not undergo treatment do need to be followed with a surveillance protocol because, over time, some patients will have tumor growth and/or progress to a higher Gleason score and eventually require treatment. Patients that have a high volume of Gleason 6 cancer may be at higher risk from their disease and benefit from treatment.
Gleason 7 – This is an intermediate score. Some elderly patients with low-volume Gleason 7 disease can be watched. Younger patients with higher-volume disease will see benefits from treatment.
Gleason 8-10 – This is a high Gleason score and is associated with higher stage. Patients with high Gleason score benefit from treatment.
What are my options if prostate cancer is suspected but my biopsy is negative?
A TRUS-guided biopsy aims to systematically sample the areas of the prostate which might harbor cancer, but is still only removing a small amount of tissue for analysis. It is not uncommon for a TRUS-guided biopsy to be negative while a cancer is still present. The degree of suspicion for prostate cancer that remains after a negative biopsy depends on how likely it is the patient had prostate cancer prior to the biopsy. This risk estimation is based on various factors including age, PSA, family history, ethnicity, etc. A prostate cancer calculator can help estimate this risk.
When a patient is suspected of having prostate cancer despite a negative biopsy, a number of options are available:
PSA surveillance – following PSA values for a while to see if they go up or down is an approach often employed after a negative biopsy. A rising PSA after a negative biopsy is often a trigger for a biopsy to be considered, while a declining PSA is reassuring. Some patients undergoing PSA survaillance may never need a repeat biopsy.
Repeat biopsy – repeating a TRUS-guided biopsy after one negative biopsy is common, particularly when there is a high suspicion of prostate cancer. It is common to find cancer on a repeat TRUS-guided biopsy after an initial negative biopsy. After 2 negative biopsies, each additional biopsy is unlikely to find prostate cancer. A repeat biopsy usually follows a period of PSA surveillance.
MRI – performing a MRI of the prostate gland can provide additional information about how likely a patient is to have prostate cancer. A negative MRI is reassuring, and patients with a negative MRI are unlikely to have prostate cancer. A MRI can sometimes directly indicate the location of a tumor, thereby guiding future biopsies to this visualized tumor.
PCA-3 – this is a urine test that may further aid in figuring out which patients who are still likely to have prostate cancer despite a negative biopsy. This test is not covered by OHIP and costs $385. More information is available on the PCA-3 website.
Other options sometimes employed in this setting include use of 5-alpha reductase inhibitors, genomic scores, transurethral resection of the prostate, and watchful waiting.
What further tests do I need after a biopsy?
Patients with a high Gleason score, locally-advanced disease, or a high PSA (usually 20 ng/ml or more) should have a workup to look for metastatic disease. This involves a computed tomography (CT) scan of the abdomen and pelvis and a bone scan. This will look for lymph node and bone metastases respectively. There are rare situations when additional investigations are warranted.
Patients without a high Gleason score, locally-advanced disease, or a high PSA, usually do not need any additional staging investigations.