Prostate cancer occurs in the prostate, a gland in the male reproductive system. Read more about prostate cancer here.
Diagnostic tests are performed on the patient to confirm the stage and type of the cancer. These tests also give complete information of the patient’s medical condition which helps the doctors prescribe the best treatment to cure prostate cancer.
The factors that are considered in order to choose the best diagnostic tests are:
- Medical history of the patient
- Signs and symptoms
- Age
- Suspected type of cancer
Read more about signs and symptoms of prostate cancer here.
The following diagnostic tests are performed to diagnose prostate cancer grouped based on their stage of diagnosis:
Preliminary tests:
PSA test:
This test are done to check the levels of prostate specific antigen (PSA) which are released by the prostate tissues. Abnormal levels of the PSA indicates prostate cancer, BPH or inflammation of the prostate. Doctors monitor the levels of PSA value and go for a biopsy based on the relation between the growth of PSA and the the size of the prostate, which is known as PSA velocity.
Free PSA:
This is a type of PSA test that is performed to measure the free PSA in the bloodstream. The free PSA is not bound to proteins. This test gives the ratio of free PSA to total PSA, which helps in finding out if prostate cancer is the cause of higher PSA levels in the body.
Digital rectal examination (DRE):
Digital rectal examination is carried out by the doctor feeling the prostate area using a finger. This test does not give accurate results though and early stages of prostate cancer cannot be detected through DRE.
Biomarker tests:
Biomarkers are substances that the tumours make in the blood, urine or tissues. A score of 4K of the biomarker tests indicate higher risks of the patient developing prostate cancer.
Confirmation of diagnosis of prostate cancer:
On observing any abnormalities in the PSA or DRE, the cancer is confirmed after performing the following diagnostic tests:
PCA3:
The prostate cancer gene 3 check for the PCA3 gene in a man’s urine. The urine test alone helps the doctors find out about the presence of this gene in the body. It is often performed along with a PSA test. Based on these diagnostic results, a decision regarding prostate biopsy is taken.
Transrectal ultrasound (TRUS):
This test is often done along with biopsy. It is carried out by inserting a probe into the rectum which takes a picture of the prostate using sound waves.
Biopsy:
A biopsy is recommended to confirm the presence of malignant cells in the prostate. It is performed by removing a small amount of tissue of the prostate and examine it under a microscope to check the presence of malignant cells. The tissue samples are removed using a TRUS and a biopsy tool. Small incisions are made in the prostate region and twelve to fourteen pieces of tissue from different regions of the prostate are removed to increase the precisity of the diagnostic result.
MRI fusion biopsy:
This is the most commonly used diagnostic test in order to confirm biopsy. The MRI fusion biopsy is a combination of MRI scan and TRUS. Patients receive MRI scan which gives a clear picture of the exact location of the tumours or cancer cells.
Checking for metastasis:
The results of the above tests can confirm the presence of prostate cancer, but they cannot relay how far the cancer has spread in the body. The following tests are performed to check the extent of spreading of prostate cancer:
Whole-body bone scan:
This scan uses Technetium-99, a radioactive tracer to check the inside of the bones. It is given intravenously and collects in areas of the bone where metabolic activity has occurred. The scan shows gray color for healthy cells and dark for malignant cancer cells.
Computed tomography (CT) scan:
This scan uses X-rays that are projected on the patient’s body in different angles. It combines these images in a precise, cross sectional to produce a 3D picture of the inside of the body. A CT scan is also used to measure the size and abnormalities of the tumours. Often contrast medium is prescribed to the patient before the scan. It is a special dye, which is given intravenously or orally, that can increase the precisity of the images that are depicted.
PSMA-Positron emission tomography (PET) scan:
This scan is carried out by injecting a small amount of radioactive substance in the body. These substances are absorbed by cells that tend to be more active. This accumulation and absorption are monitored by a doctor during the scanning.
Magnetic resonance imaging (MRI):
This test uses magnetic rays to determine the size of the tumour. Before the scan, the patient is intravenously or orally given a contrast medium which helps in giving clearer images of the inside of the body.
Staging of prostate cancer:
Staging of prostate cancer helps the doctors figure out how much the cancer has spread in the prostate gland and determine its best treatment. Staging also helps calculate survival statistics. The lower the number of the stage, the less is the cancer has spread, with early stages being 1 and the most advanced stage being 4. Read more about treatment options for prostate cancer here.
How is prostate cancer staged?
Cancer types that form tumours are usually staged using TNM system and the same method is used for prostate cancer too. The size of the primary tumour (T), the presence of cancerous lymph nodes (N) and how far the prostate cancer has spread to a different part of the body (M) can be described using the TNM system. Additionally, PSA levels and grade of tumour is also taken into consideration for prostate cancer. The stage of the cancer determines the extent to which the cancer has metastasized.
Tumour (T):
The stages are divided based on the size and extent of the cancer tumour in the primary location and the stages are Tis (T0) to T4.
TX stage: The primary tumour cannot be evaluated or staged.
T0 stage: The tumour shows no signs or evidence.
T1 stage: The tumour cannot be felt during a DRE or seen in imaging tests, but can be found during other surgical procedures.
T2 stage: The tumour is confined to the prostate and is large enough to be felt during a DRE.
T3 stage: The tumour has grown through the prostate and into the tissue outside on one side of the prostate gland or to the seminal vesicles.
T4 stage: The tumour has grown out of the prostate gland into nearby structures such as the external sphincter, the rectum, the bladder, the levator muscles or to the pelvic walls.
In addition to the tumour staging, a prefix can be attached before the stage to show if the tumour has been staged clinically or pathologically (c for clinical and p for pathological).
Node (N):
The node describes whether the cancer has spread to the lymph nodes or not.
N0 stage: Shows that there are no lymph nodes containing cancer.
N1 stage: There is a presence of 1 to 3 cancerous lymph nodes.
N2 stage: 4 or more lymph nodes contain cancerous lymph nodes, which means that the cancer can further spread in the body.
Metastasis (M):
This gives information about the cancer spreading to other parts of the body.
M0 stage: The cancer has not spread to other distant parts of the body.
M1 stage: The cancer has spread to other body parts also.
PSA level:
The prostate gland produces a protein known as Prostate specific antigen or PSA. It is present in small quantities in men with healthy prostates but is elevated in the presence of prostate related disorders or prostate cancer. The PSA tests can be used to measure the levels of this protein in the patient and can be used to stage the cancer. Read more about PSA here.
Grade:
Grade is a parameter used to describe how closely the cancerous cells represent normal cells of organ, in this case, the prostate gland. In prostate cancer, Gleason score is the grading system used to determine the grade of cancer and hence its aggressiveness. The Gleason score ranges from 2 to 10. A normal range of Gleason score is from 1 to 5 with cancers with cancer usually having Gleason scores of 3 or higher.
The overall Gleason score of the tumour is determined based on the two major regions of cancer growth and the Gleason sum of those regions. The Gleason sum 3+4=7 signifies that the largest tumour growth has a Gleason score of 3 and the next largest, 4. If there is a single tumour or uniform growth of cancer, the Gleason score is doubled to get the overall score.
Grade groups are determined based on the overall Gleason scores.The following are the grade groups based on the Gleason scores of the cancer.
- Grade Group 1: Gleason 6 or less
- Grade Group 2: Gleason 3+4=7
- Grade Group 3: Gleason 4+3=7
- Grade Group 4: Gleason 8
- Grade Group 5: Gleason 9 or 10
The Grade groups are further classified into three categories on the basis of differentiation.
- Gleason 6 or lower: Well differentiated
- Gleason 7: Moderately differentiated
- Gleason 8 to 10: Poorly differentiated or undifferentiated cells
What are the stages of prostate cancer?
There are four stages of prostate cancer, the exact stages and their features will be discussed in the further articles along with their treatment options for each stage.
- Stage I prostate cancer and its treatment
- Stage II prostate cancer and its treatment
- Stage III prostate cancer and its treatment
- Stage IV prostate cancer and its treatment