Understanding Prostate Cancer
What is Cancer?
Cancer occurs when cells multiply out of control, rather like a factory with the production line switch jammed on. The cells do not know when to stop multiplying and as a result grow into other tissues and spread to other parts of the body. In the case of prostate cancer it is usually fuelled by the male hormone, testosterone and in fact for treatment for some prostate cancers the lowering of testosterone is the corner stone.
Causes of Prostate Cancer
Prostate cancer tends to run in families and if a man’s father has or has had a prostate cancer the likelihood of getting it can be increased by one and a half to two and a half times. The absolute risk is 12-20%. For two affected male relatives absolute risk is approximately 30%, three or more affected males relatives 35-45%. As men get older the risk of prostate cancer increases but it is possible that the risk of dying from prostate cancer may decrease. It is possible that men may therefore die of other causes, such as old age, heart disease, etc. There is no absolutely definite association with any particular type of diet and studies linking vasectomy with an increased risk of prostate cancer have not been confirmed. A man with Prostate Cancer who has intercourse will not “stir up” the cancer causing it to spread and will not pass it on to a partner.
Diagnosis of Prostate Cancer
When a man visits his doctor, the doctor will ask questions about symptoms which have led the patient to present. This is called a history. In some cases there may be no symptoms at all associated with prostate cancer and screening may be carried out in some men by the performance of a blood test which estimates the level of Prostate Specific Antigen, (PSA) in the blood stream.
PSA and testing for Prostate Cancer
PSA is a blood test, which measures the level of a substance in the blood stream which is only present in men. It is made in the prostate gland and leaks into the blood stream and is specific for prostate but not specific for prostate cancer.
There are two types of PSA. The PSA which is free within the circulation and that which is bound to a protein. A number of studies have shown that the ratio of free to bound PSA may result in a greater sensitivity in the possibility of being able to estimate the likelihood of a prostate cancer in an individual patient. Generally speaking, if the ratio is less that 10-15% the likelihood of a prostate cancer is increased.
The blood test may go up with things other than prostate cancer. It may go up if the prostate is enlarged, (benign or non-cancerous) which occurs as men get older or go up because of infection. Not all prostate cancers cause the blood test to go up but many do. Some patients have unsuspected prostate cancer diagnosed when the Pathologist examines the specimen after they have undergone Transurethral Resection of the Prostate (“rebore”) as treatment for obstructive urinary symptoms.
Survival
Eighty-five percent of all prostate cancers are discovered as low stages (localised). The 5-year relative survival rate for patients whose tumours are diagnosed at these stages are close to 100% cancer specific. Over the past 20 years, the 5-year survival rate for all stages combined has increased from 67% to 98%. According to the most recent data, relative 10-year survival is 84% and 15-year survival is 56%.
(Source: American Cancer Society, Cancer Facts and Figures 2004, page 17.)
Examination
In addition to the blood test, a digital rectal examination, (DRE) is carried out by the Doctor. For this examination the doctor inserts a gloved finger into the patient’s back passage in order to feel the prostate gland. The Doctor is feeling for the size, shape, consistency and any irregularity suggestive of cancer. If either the PSA or DRE is abnormal, the doctor may suggest a biopsy be taken.
Biopsy
A biopsy from the prostate is a small piece of tissue which is taken with a special needle. It is usually necessary for the prostate to be examined with a transrectal ultrasound, (TRUS) which is carried out without the need for anaesthetic. This examination is carried out by placing the Ultrasound probe in the back passage in a similar fashion to the DRE. The TRUS enables the prostate to be visualised looking for any abnormal areas, which may or may not be felt on the DRE. If abnormal areas are seen, the biopsy needle can be directed towards them. If no abnormalities are seen then it is usual to biopsy areas which are more likely to undergo a cancerous change. This usually means at least six to eight biopsies.
Pathology
The specimens taken are sent to the Pathologist for preparation and examination under the microscope. The only way any cancer can be diagnosed correctly is by the visualisation in the pathology specimen.
Gleason Score
A Gleason Score is a number given to the type of prostate cancer cells in an attempt by the Pathologist to say “how bad” the cancer might be. It is a method of grading the tumour. A Gleason Score is a number ranging from 2 to 10.
Gleason Scores of 2 are what is referred to as “well differentiated” tumours which are likely to respond to treatment better than a Gleason Score 10 which is usually described as “undifferentiated” in that it looks nothing like the normal non-cancerous prostate tissue at all.
Staging
After the tumour has been graded it is necessary to carry out staging. Staging means trying to find any evidence of spread outside the prostate. Often a CT Scan, Ultrasound or MRI, (Magnetic Resonance Imaging) is used to inspect the abdominal cavity in order to attempt to detect any spread to the internal lymph glands or lymph nodes.
The glands or lymph nodes are small, bean - sized areas within the body which are associated with the body’s immune system and tend to fight infection and cancer. For example if a patient has a sore throat, the glands in the neck are easily felt and often tender and swollen from the infection. If a patient has a cancer of the throat, the cancer may spread to the glands of the neck. In similar fashion a prostate cancer may spread to the glands inside the body.
The information gathered from the staging process determines the stage of the disease. It is important to know the stage in order to plan treatment.
As prostate cancer progresses from Stage I to Stage IV, the cancer cells grow within the prostate, through the outer layer of the prostate into nearby tissue, and then to lymph nodes or other parts of the body.
The following stages are used for prostate cancer:
In stage I, cancer is found in the prostate only. It cannot be felt during a digital rectal exam and is not visible by imaging. It is usually found accidentally during surgery for other reasons, such as benign prostatic hyperplasia. The Gleason score is low. Stage I prostate cancer may also be called stage A1 prostate cancer.
In stage II, cancer is more advanced than in stage I, but has not spread outside the prostate. The Gleason score can range from 2-10. Stage II prostate cancer may also be called stage A2, stage B1, or stage B2 prostate cancer.
In stage III, cancer has spread beyond the outer layer of the prostate to nearby tissues. Cancer may be found in the seminal vesicles. The Gleason score can range from 2-10. Stage III prostate cancer may also be called stage C prostate cancer.
In stage IV, cancer has metastasized (spread) to lymph nodes near or far from the prostate or to other parts of the body, such as the bladder, rectum, bones, liver, or lungs. Metastatic prostate cancer often spreads to the bones. The Gleason score can range from 2-10. Stage IV prostate cancer may also be called stage D1 or stage D2 prostate cancer.
(Source: National Cancer Institute)
Bone Scan
Prostate cancer has a tendency to spread to the bones of the body, chiefly to the back. A bone scan is a Nuclear Medicine imaging procedure which involves an injection of extremely low dose radio - nucleotide material into a vein, usually in the arm which then circulates through the body and is able to show up areas of spread of prostate cancer to bone.
Treatment of Prostate Cancer
The object of treatment of prostate cancer or any any other condition for that matter is such that the treatment should enable the patient to live longer and better than otherwise the patient would do without the treatment. The treatments which would be discussed for prostate cancer will depend on the following factors:
- Grade of cancer
- Stage of cancer
- Patient’s age
- Patient’s general state of health, other medical conditions
- Patient’s fears, anxieties and preferences
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