Prostate cancer terminology

Dr Shivona Moodley expands on the common terminology that is used in the diagnosis and treatment of prostate cancer.

Prostate cancer (PC) is the second most common cancer in men with 1,4 million new cases being diagnosed in 2020, according to GLOBOCAN statistics. Southern Africa had the third highest worldwide mortality rates from PC. In South Africa, the National Cancer Registry 2014 report confirms that PC is the most common histologically-diagnosed malignancy in non-Caucasians, and the second most common cancer in Caucasians. 

Routes of spread 

PC starts in the cells of the prostate gland and the most common type of cancer found here is adenocarcinoma. It’s usually a slow-growing disease and stays in the prostate gland. The routes of spread are categorised by:

Localised: when prostate cancer cells remain within the prostate gland.

Regional: if the cells migrate out of the prostate gland to the nearby lymph nodes.

Metastatic: If the cells migrate beyond the prostate or regional lymph nodes to other areas.

PC can spread through the lymphatic channels to the lymph nodes, or via the blood to the lungs, liver, bone and other organs.

Testing 

Prostate specific antigen (PSA) is a protein that is produced by the prostate. A PSA test measures the amount of PSA in a blood sample. Men with PC have elevated levels of PSA; however, a high level doesn’t necessarily mean there is cancer. There are many causes of elevated PSA levels, including benign prostatic hyperplasia (BPH), infection (prostatitis), sexual activity, and trauma (bicycle riding). Avoid ejaculation or long bike rides for at least 48 hours prior to taking your blood test to have more accurate results. 

A digital rectal exam (DRE) is performed by a medical professional and entails the insertion of a lubricated gloved finger into the rectum to allow for clinical assessment of the prostate gland. This examination is used for screening purposes, staging and to assess response to treatment. 

A prostate biopsy is a procedure where a sample of tissue is removed from the prostate and looked at under the microscope to assess for cancer cells. The urologist may use a trans-rectal ultrasound or an MRI to guide the biopsy. 

Gleason score

This describes how aggressive the cancer cells behave on a microscopic level. The biopsy specimen is looked at under a microscope by a pathologist. The cells are graded from 1 to 5, with 1 resembling normal prostate tissue and 5 representing highly abnormal cells. The higher the grade, the more abnormal the cells look with most PC being Grade 3 or more. 

A major score is assigned to the predominant proportion of the specimen and a minor score is assigned to the second most predominant part of the specimen. For example, a Gleason score of 5 (major score) + 4 (minor score) = 9 (total score) means that majority of the specimen was made up of highly abnormal cells and represents high-grade disease. 

A Gleason score of less than or equal to 6 represents low-grade disease. A score of 7 represents intermediate-grade disease and a score of 8 to 10 represents high-grade disease. The Gleason score assesses the cancer at a microscopic level while the macroscopic disease is represented by the areas of the body that are involved like the prostate gland, regional nodes and distant sites. 

Risk groups

Patients that have localised PC that is confined to the prostate gland can be placed in various risk groups and treatment options are based on these risk groups. A patient is placed in a risk group based on: 

• A TNM stage 
• Gleason score 
• Initial PSA value
• Biopsy results

The risk groups are as follows: 

• Very low-risk
• Low-risk
• Intermediate-risk favourable
• Intermediate-risk unfavourable
• High-risk
• Very high-risk

The treatment options for each risk group varies and you should ask your oncologist which risk group you belong to so that you can understand the options that are available to you. 

Treatment options

1.   Active surveillance

• This is a strategy that was implemented to decrease the overtreatment of low-risk PC. 
• It’s defined as actively monitoring the course of the disease with six monthly PSA tests and yearly DREs, prostate biopsies and imaging.
• The intention is to initiate curative therapy at time of progression. 
• The benefit is allowing men to maintain a relatively normal lifestyle and quality of life when compared to other therapeutic options, especially in younger men with low-risk disease.

2. Radical prostatectomy

• This is a curative procedure for men with localised PC. 
• It usually requires removal of the prostate gland, seminal vesicles, and surrounding tissues. Pelvic lymph nodes may also be removed. 
• There are different techniques that can be used, including an open prostatectomy, a laparoscopic- or a robot-assisted laparoscopic approach.

3. External beam radiation therapy 

• Radiation uses high energy X-rays that are produced by a machine which enter the body through the skin surface and are targeted at the prostate, seminal vesicles and lymph nodes to kill cancer cells.
• It can be used as the main treatment instead of surgery, after surgery if the PSA begins to rise, or in the metastatic setting for palliation.
• It’s a highly conformal, well-tolerated and effective form of treatment when used alone or in combination with hormone therapy, brachytherapy or both. 

4. Brachytherapy

• This is when radiation is placed inside or next to the tumour. This form of radiation travels very short distances and allows sparing of normal surrounding tissue from radiation.

• High-dose rate (HDR) brachytherapy is the temporary placement of radioactivity within the prostate gland using thin needles and catheters. The radioactive source temporarily moves through the catheters, emits a dose of radiation within the prostate gland and moves out again.

• Low-dose rate (LDR) brachy is when multiple radioactive seeds, the size of a grain of rice, are placed through the perineum into the prostate gland. These seeds stay in the prostate and emit a low dose of radiation over a few months. Over time, the seeds become dormant but will remain in your body.

• Brachy can be used alone in very low- to intermediate-risk favourable disease or in combination with external beam and hormonal therapy with higher risk disease. It can also be used in the salvage setting in patients with a recurrence following prior treatment with external beam radiation.

5. Hormonal therapy

• This is medical treatment that adds, blocks or removes hormones from the body. Testosterone is the main male sex hormone that is produced by the kidneys and adrenal glands. Testosterone can act as fuel to PC cells and cause them to grow.
• Androgen deprivation therapy is another name for hormonal therapy that blocks the production of testosterone in the body. 
• Is usually given for limited periods of time to reduce the risk of side effects which may include loss of libido, erectile dysfunction, weakening of the bone, hot flushes, diabetes and heart disease. 

6. Systemic therapy

• Includes chemotherapy, immunotherapy and bone-targeted therapy which can be useful in the advanced or metastatic setting. 

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