Prostate Cancer

Prostate cancer is the most common cancer among men worldwide, after nonmelanoma skin cancer. It is the second most common cause of cancer death among men in the US, the UK and Australia. 

Anatomy of the Prostate 

The prostate is a small gland in the pelvis in men. It is part of the male reproductive system. A normal prostate is the size of a walnut. It is located below the bladder and just in front of the rectum. It surrounds the first part of the urethra—a tube that carries urine from the bladder to the penis. The main function of the prostate is to generate semen and protect sperm. Prostate cancer is an abnormal growth of cells in the prostate gland.

Risk Factors 

Some risk factors for prostate cancer include the following.

Age: The risk of prostate cancer increases with age. This cancer is less common among men younger than 45, and more common among men older than 65.

Family history: Research has shown that a man is 2.5 times more likely to develop prostate cancer if his father or brother has been diagnosed with it, compared to a man who has no relatives with prostate cancer. Five to 10% of all prostate cancers are linked to genes. Research has found that changes in two genes called ‘BRCA1’ and ‘BRCA2’ increase a woman’s chance of developing breast and ovarian cancer, and increase a man’s chance of developing prostate cancer.

Ethnicity: Prostate cancer is more common among black men than Caucasians or Hispanics.

Contrary to previous beliefs, researchers have found that vasectomies, tobacco use, alcoholism, sexually transmitted infections, obesity, lack of exercise and diets high in animal fat and meat do not increase the risk of prostate cancer.

 

Symptoms 

A patient may not experience any symptoms of prostate cancer; however, some symptoms of prostate cancer may include the following.

Urinary symptoms: 

  • inability to pass urine
  • waking frequently during the night to urinate
  • a sudden urge to urinate
  • difficulty urinating
  • mild discomfort when urinating
  • a slow flow of urine and difficulty stopping
  • blood in the urine or semen.

Sexual symptoms: 

  • a decreased sexual drive (low libido)
  • difficulty getting an erection
  • painful ejaculation.

Other symptoms are usually seen when the disease has spread to other parts of the body, such as the bones. These symptoms may include back pain, hip pain, fatigue and unexplained weight loss.

 

Diagnosis 

The diagnosis of prostate cancer is based on the patient’s history, including a family history of prostate cancer; a general physical examination; a DRE; a blood test for PSA and other tests.

DRE: In this examination, the doctor inserts a gloved finger into the anus and feels the parts of prostate. This is the best way to examine the prostate because it lies directly in front of the rectum. The doctor feels for any irregularities of the prostate, including enlargement, hardening, or any other lumps or bumps on the surface of the prostate. The patient may experience some discomfort or minor pain during this procedure. Some people may find it embarrassing. DRE is done by either a local doctor or surgeon.

PSA blood test: This test looks for the presence of a protein in the blood that is produced specifically by the prostate, called a ‘prostate-specific antigen’. The values of PSA increase with age. A very high value suggests prostate cancer. If the PSA is slightly elevated, the doctor will repeat the test at regular intervals to determine whether it changes.

Transrectal ultrasound and biopsy: If PSA is increased or the doctor finds abnormalities during DRE, the doctor will order a transrectal ultrasound. In this procedure, a probe is inserted into the rectum to check the prostate for abnormal areas. The ultrasound generates an image of the prostate on a computer screen and guides the doctor to insert needles into the abnormal areas to take a biopsy. The biopsy samples will be analysed by a pathologist.

If the biopsy shows cancer, the stage and grade of cancer will be determined.

The biopsy will probably show one of the following four likely results:

  • normal prostate tissue
  • atypia or dysplasia of the prostate—this means the prostate cells neither look normal nor cancerous
  • prostatic intraepithelial neoplasia—this is a transition stage between normal tissue and cancer of the prostate
  • prostate cancer.

 

Other tests: Other tests are mainly done to determine whether the cancer has spread to other parts of the body, such as the bones. These tests may include:

  • a chest X-ray
  • a CT scan  an MRI scan
  • a bone scan.

 

Grading and Staging 

The grading of prostate cancer is done by a pathologist after analysing the biopsy of the prostate. The system is called the Gleason Scoring System. The higher the score, the more aggressive the cancer.

Gleason score  Aggressiveness of cancer 

2–4 low

5–6 moderate

7 intermediate

8–10 high

 

The staging of prostate cancer following the TNM system is as follows.

Stage I: In this stage, the cancer is confined to the prostate only. It cannot be felt during DRE or seen on ultrasonography. The Gleason score is no higher than four.

Stage II: In this stage, the tumour still has not spread beyond the prostate, but it is more advanced than Stage I. It may be felt during a DRE or seen on an ultrasonography.

Stage III: In this stage, the tumour has extended beyond the prostate and may have invaded the seminal vesicles, but has not spread to the lymph nodes.

Stage IV: In this stage, the tumour may have spread to the bladder, rectum or nearby structures. It may also have spread to the lymph nodes, bones and other parts of the body.

 

Treatment 

In the majority of cancer cases, a general practitioner or family physician coordinates the diagnosis and treatment of prostate cancer, and refers patients to appropriate professionals as required. The treatment team may consist of:

  • surgeons
  • urologists
  • radiation oncologists
  • medical oncologists
  • palliative care physicians
  • palliative care surgeons
  • specialist nurses
  • psychologists
  • counsellors
  • social workers.

 

There are many options available to treat prostate cancer. The treatment options depend on the grade of the cancer and whether the cancer is contained within the prostate gland or has spread to other parts of the body. The choice of treatment may also depend on other factors, including the general health, age and personal preferences of the patient, and the progress of the cancer. The available treatment options include:

  • watchful waiting or active surveillance
  • surgery
  • radiation therapy
  • hormone therapy
  • chemotherapy

 

Watchful waiting or active surveillance 

This involves regular PSA tests, DRE and ultrasounds to see whether the cancer is growing. If these tests show that the cancer is growing or worsening, active treatment may be recommended. This type of approach is not a good option if the patient is young and healthy, or the cancer is fast growing, as evidenced by a high Gleason score. Active treatment is recommended in such cases.

 

Surgery 

There are many types of surgery for prostate cancer, with each type having its own benefits and risks. The patient needs to discuss each type of surgery in detail with a surgeon and choose the right one. Generally, surgery is a good option for Stage I and II prostate cancer. The following procedures may be used:

  • Radical prostatectomy: This surgery is intended to cure the prostate cancer by removing the entire prostate gland and the tissues around it, including the seminal vesicles.
  • Radical retropubic prostatectomy: In this operation, the surgeon makes a cut in the abdomen and removes the entire prostate.
  • Radical perineal prostatectomy: In this operation, the surgeon removes the entire prostate through a cut between the scrotum and the anus (perineum).
  • Laparoscopic radical prostatectomy: In this operation, the surgeon makes small cuts in the abdomen and, with the help of a laparoscope, removes the entire prostate through these cuts.
  • Robotic-assisted laparoscopic radical prostatectomy: This is similar to laparoscopic radical prostatectomy, but the surgeon uses a robot to help.
  • Transurethral resection of the prostate: This procedure is done for advanced prostate cancer to relieve symptoms only. Through the urethra, the surgeon inserts a long, thin scope that has a cutting tool at the end. The scope removes tissue from the inside of prostate that blocks the flow of urine, thereby relieving urinary blockage.

 

Complications of prostate surgery  

In addition to the common complications of surgery, such as pain, bleeding and infection of the operation sites, other complications of prostate operations include the following:

  • the catheter may need to be left in the urethra for one to two weeks or more
  • loss of control of urine (urinary incontinence)
  • impotence or the inability to have an erection because nerves can be damaged during surgery
  • if the prostate is removed, the patient will not produce semen and will have dry orgasms.

 

Radiation therapy 

Radiotherapy can be used during any stage of prostate cancer. Radiation therapy can be used instead of surgery, after surgery to treat remaining cancer, or in the advanced stage of cancer to relieve pain. The two types of radiotherapy are as follows.

External radiation: External beam radiotherapy is the traditional method of delivering radiation. Short pulses of tightly focused beams of X-rays are delivered from outside the body into the prostate for a few minutes each day. Treatment continues five days a week for about seven weeks. Image guided radiotherapy and intensity-modulated radiotherapy are two new techniques that allow the radiotherapy beams to best target the prostate and spare the surrounding normal tissues. These techniques provide cure rates almost equivalent to those of surgery and brachytherapy. The complications are minimal and the procedures suit both younger and older men. Treatments are given in a hospital or cancer clinic and usually last eight weeks.

Internal radiation or brachytherapy: In this procedure, the radiation comes from radioactive material contained in very small implants, called ‘seeds’. Dozens of seeds are placed inside needles, and the needles are inserted into the prostate. The needles are then removed, leaving the seeds behind. The seeds give off radiation for a few weeks or months. They do not need to be removed once the radiation is gone

 

Side effects of radiotherapy  

 

The side effects of radiotherapy may include:

  • tiredness
  • loss of appetite
  • diarrhoea
  • hair loss
  • red, dry and tender skin at the radiation site
  • urine incontinence
  • urinary frequency and urgency
  • the inability to have an erection (impotence).

 

Hormone therapy 

Male hormones (androgens) can cause prostate cancer to grow. Hormone therapy works by stopping the body producing testosterone or stopping testosterone reaching the prostate cancer cell. Hormone therapy can be given before, during or after radiation therapy. If the cancer has already spread to other organs or to the bone at the time of diagnosis, hormone therapy becomes the primary method of treatment. It is also used when the cancer returns after treatment. Hormone therapy does not cure prostate cancer, but can control the cancer for many months or years. The types of hormone therapy employ the following drugs:

  • LHRH agonists: These drugs can prevent the testicles from making testosterone. Examples include leuprorelin (lucrin) and goserelin (zoladex).
  • Anti-androgens: These tablets block the male hormone, testosterone, from reaching the cancer cells. Examples are bicalutaide (casodex) and cyproterone (androcur, cyprostat).
  • gonadotropin-releasing hormone (GnRH) antagonists: This type of drug is given by injection and only available in some hospitals. Currently, there is only one kind of GnRH antagonist called degarelix (firmagon).

Surgery to remove the testicles (orchidectomy) is sometimes done so that no testosterone can be produced after the operation.

 

Side effects of hormone therapy  

The side effects of hormone therapy can include:

  • low or no sexual desire
  • the inability to get an erection (impotence)
  • hot flushes
  • breast tenderness and the growth of breast tissue
  • loss of muscle mass
  • thinning of bones (osteoporosis)
  • weight gain
  • fatigue
  • forgetfulness and concentration problems  mood changes.

 

Chemotherapy 

Chemotherapy for prostate cancer is used if the cancer has spread outside the prostate gland or if hormone therapy does not work. It does not cure cancer, but may slow the cancer’s growth and reduce symptoms, resulting in better quality of life. Some anticancer drugs used in prostate cancer include docetaxel, cabazitaxel and mitoxantrone.

 

Some side effects of chemotherapy include: 

  • hair loss
  • mouth sores
  • loss of appetite
  • nausea and vomiting
  • infections due to low white blood cell counts
  • easy bruising or bleeding due to low blood platelets
  • fatigue due to low red blood cell levels.

 

HIFU 

HIFU is a new therapy for prostate cancer that uses intense heat applied through the rectum to destroy the prostate and the cancer within. This treatment is very useful for older patients who are unsuitable for or refuse surgery or radiotherapy. This therapy can also be used when radiotherapy fails. The side effects of HIFU may include difficulty passing urine, frequency and burning pain during urination, temporary incontinence and some risk of infection. These symptoms usually disappear after three months.

 

Follow Up 

The patient requires a regular check-up after treatment for prostate cancer. This will help the doctor monitor the general health of the patient, monitor any problems associated with treatment, and check for signs of the cancer returning. Initially, the check-up may be every four to six weeks, then every three to six months, then less often after that. Check-ups may include a DRE and PSA test. A rise in the PSA level can mean that the cancer has returned after treatment. The doctor may also order a biopsy, bone scan or CT scan if he or she suspects that the cancer may have returned.

 

Prognosis 

The prognosis depends on the type and stage of cancer and age and general health of patient at the time of diagnosis. Almost all patients with localised cancer will live beyond five years, while about 93% live beyond 10 years.

Prevention 

There is no proven measure to prevent prostate cancer. Thus, the focus should be on the early detection and treatment of cancer.

 

Screening 

At present, unfortunately, there is no universally accepted screening program for prostate cancer. The Cancer Council of Australia recommends that men should be given the chance to make an informed decision with their doctor about whether to be screened for prostate cancer or not. This decision should be made only after receiving information about the uncertainties, risks and potential benefits of prostate cancer screening, as well as discussing the treatment options and side effects. Discussions about screening should consider the age of the patient and other individual risk factors, such as a family history of prostate cancer. After this discussion, those men who wish to be screened should be tested with the PSA blood test and DRE.

 

New Developments in Prostate Cancer 

A new medication called sipuleucel-T (provenge) was approved to treat advanced prostate cancer by the US Food and Drug Administration in April 2010. This is a vaccine that works by activating the patient’s own immune system to attack prostate cancer cells. Compared to other prostate cancer treatments, provenge is very expensive and is not currently available in most parts of the world, including Australia, for prostate treatment.

 

Get your prostate examined!!

 

References: ‘Do I Have Cancer?’ Signs, Symptoms, Diagnosis, and Treatment of Fifty Common Cancers by Dr N Parajuli