Prostate cancer is a type of cancer that occurs in males. In fact, it is the third most common cancer in Singaporean men1.
The prostate gland is a small gland located below the bladder near the base of the penis. It produces white-coloured fluid that mixes with sperm to form semen.
Image from American Cancer Society
Prostate cancer occurs when there is an abnormal growth of prostate gland cells. Almost all prostate cancers are adenocarcinomas (cancers that start from cells that line glands, which in this case is the prostate gland).
The biggest risk factor for prostate cancer is increasing age. Prostate cancer usually occurs after the age of 50 and is most common in those over 70 years of age.
Only 4.3% of prostate cancer cases were diagnosed in patients aged <55, while 24.6% of cases were diagnosed in the age group of 55-64, and 71.1% of cases were diagnosed amongst those >641.
A small proportion of prostate cancers are due to genetic predisposition. Patients who carry germline mutations in their DNA-repair genes are more likely to develop prostate cancer, regardless of whether they have a family history of prostate cancer. These mutations are built into the genes, and hence can be passed down to children.
4.6% of patients with localised prostate cancer have these genetic mutations, while 11.8% of patients with metastatic prostate cancer have the mutations.2 Localised prostate cancer means the cancer is confined to the prostate gland, whilst metastatic cancer means that the cancer has spread beyond the prostate gland.
Those with a positive family history for prostate cancer are at higher chance of contracting cancer. Having a first-degree relative (such as a father or brother) with prostate cancer increases a man’s risk of having prostate cancer in the future.
A diet high in lycopene (tomato-based) or cruciferous vegetables (broccoli and cauliflower) is linked to a less lethal form of prostate cancer. This can be helpful as some prostate cancers can be slow-growing and do not cause issues. On the other hand, other types of supplements such as Vitamin E and Selenium, have not been shown to help cancer.
There are two main screening tests used to test for prostate cancer. The first is a PSA test, and the second is a digital rectal exam.
Since abnormal PSA levels could indicate the presence of prostate cancer, PSA tests might be used as a preliminary screening test for prostate cancer. This test is sometimes included in comprehensive health or cancer screening packages for males.
A PSA test is a blood test that measures the amount of PSA in your blood.
While abnormal PSA levels can indicate cancer, PSA levels can also be elevated because of
On the other hand, PSA levels can also be suppressed by other factors such as taking certain medications.
Due to the limitations of the test, PSA screening for prostate cancer is a very controversial area. There is a variation in the recommendation for PSA screening from major bodies such as the American Cancer Society, United States Preventive Services Task force (USPTF) and United Kingdom National Screening Committee.
The benefits to screening need to be weighed against the potential for:
Based on the 2018 USPTF recommendation, PSA testing can be considered for average-risk (no family history) males aged between 55 to 69, who have a life expectancy in excess of 10 years after discussion with a physician on the pros and cons of the screening.
The decision to screen is considered individually for each patient, especially for higher-risk (positive family history) males.
If the prostate gland has cancer, it can result in abnormal bumps or hard areas on the prostate gland. Thus, such abnormalities might indicate the presence of prostate cancer.
A Digital Rectal Examination (DRE) is a simple screening test to check for prostate cancer. During this test, the doctor inserts a gloved finger into the rectum to feel the prostate. This allows them to judge if the prostate has abnormal bumps or hardness.
Image from National Cancer Institute
PSA test and Digital Rectal Exam do not conclusively diagnose prostate cancer. Having abnormal test results does not mean you have cancer. The physician might recommend a prostate biopsy to diagnose cancer.
It is advisable to first confirm the presence of raised PSA levels through a repeat PSA test. If the results are abnormal, the doctor may recommend a prostate biopsy to confirm if the presence of cancer.
Prostate biopsy is a diagnostic test for prostate cancer. The biopsy allows the doctor to remove a small amount of prostate cells that are suspected to be cancerous. The sample of cells will be analysed under the microscope to determine if they are cancerous.
Prostate biopsy is generally safe with a small risk of infection and rarely inflammation of the prostate or urinary retention.
It is usually performed via an ultrasound-guided procedure through the rectum (also known as a TRUS biopsy).
It is less commonly done through the perineum. Occasionally, MRI-directed prostate biopsy is used in patients who have rising PSA but prior negative prostate biopsy.
An MRI scan of the prostate gland may provide information on high risk features such as spread of cancer to regional lymph nodes or extension of prostate cancer beyond the prostatic capsule. A bone scan and CT scan may be done to exclude distant metastasis (when cancer is spread to other parts of the body). The physician may discuss your suitability for sensitive novel imaging techniques such as PSMA-based PET and whole-body MRI on a case-by-case basis.
While prostate cancer is the sixth most common cause of death among Singaporean men who have cancer, not all men with prostate cancer die of this condition. The treatment and the outcomes will depend on the extent (staging) of cancer at the point of diagnosis.
The treatment options for prostate cancer depend on the patient’s age and general health, PSA level, Gleason score (a grade of how aggressive prostate cancer cells look), and the stage of the cancer.
Localised (confined to the prostate) prostate cancer is treated with either active surveillance, surgery, or radiotherapy. Your doctor will select treatment options for you based on a risk stratification scale that is determined by looking at your:
• Gleason score
• PSA level
• local extent
• percentage of prostate biopsy cores that are positive for cancer
Metastatic (spread beyond the prostate) prostate cancer is treated with androgen-deprivation therapy (ADT) and/or chemotherapy and novel antiandrogen.
Patients with small, low Gleason score prostate cancers which are at low risk of progressing or spreading.
Active Surveillance is not a “treatment”. Instead, the physician will monitor the prostate cancer via regular PSA blood tests, digital rectal exams, as well as prostate biopsies.
The goal of surveillance is to avoid treatment-related complications in men who are at low risk of prostate cancer progression. That is because prostate cancer can be slow-growing, and might not cause medical problems.
Thus, no medical treatment will be administered unless there is signs or risk of progression of cancer. Curative-intent (Intent to cure) treatment will be delivered if there is clinical progression.
Radical prostatectomy (removal of the prostate gland) can be performed either via a minimally invasive surgery (robotic or laparoscopic/key-hole) or an open surgery. All prostate tissue is removed during surgery, and the experience of the surgeon is important for the best surgical outcome.
Potential complications of surgery include urinary incontinence and erectile dysfunction.
Laparoscopic/key-hole surgery is done through a small incision (cut). Then, a camera or scope is inserted in the incision. It allows the surgeon to see and remove prostate gland tissues. Robotic surgery includes the use of robotic arms to help the surgeon make more precise movements.
On the other hand, an open surgery is traditionally done with a long incision across the abdomen. As the cut is large, this type of surgery has a longer recovery time and more bleeding and pain compared to robotic or laparoscopic surgery.
Radiotherapy uses radiation to kill cancer cells. There are two types of radiotherapy that can be used in treatment:
Image from Cancer Research UK
Image from Prostate Cancer Foundation of Australia
Potential Complications
Metastatic prostate cancer typically involves the bones. The cornerstone of treatment is androgen-deprivation therapy (ADT), either in the form of surgical castration or medical castration using gonadotrophin-releasing hormone agonist or antagonist. By depriving prostate cancer cells of testosterone stimulation, the majority of the cancerous cells will regress. In some situations, novel antiandrogen or chemotherapy may be added to ADT right at the start of treatment, if the patients have metastatic disease at presentation.
If the cancer progresses after ADT, other treatment options include the use of novel antiandrogen, chemotherapy, bone targeting alpha-emitting radioisotope or PSMA radioligand.
There is still ongoing research in terms of:
The physician will work closely with the patient to determine the ideal treatment plan that suits the patient’s needs.
Book an appointment with our doctors at The Cancer Centre for a prostate cancer screening or treatment today.
Updated on 3 January 2019
DR WONG SENG WENG
Medical Director & Consultant
MBBS (Singapore), MRCP (UK), FAMS (Medical Oncology)