Prostate Cancer

written by Dr George Lee Eng Geap on 19 October 2011

Prostate Cancer

Prostate cancer is the third-leading cause of cancer deaths among men in the Western world. Early stage prostate cancer can be treated and cured.
 
What is the prostate cancer?
 
The prostate gland is a small, walnut-sized gland in men. It is located between the bladder (which stores urine) and urethra (which drains urine within the penis). The prostate gland lies in front of the rectum, and this allows the gland to be assessed by rectal examination. The prostate secretes fluid that makes up part of the semen and facilitates the transfer of sperm for reproduction. 
 
The three commonest problems of prostate are benign prostatic hyperplasia (BPH), prostatitis and cancer.
 
Prostate cancer is the most common in older men. The presence of certain prostate cancer in elderly men may be silent and will not cause symptoms or progress beyond the prostate gland during their lifetime. Even in younger men, prostate cancer may be small, slow growing and present limited risk to the patient. Clinically important prostate cancers can be defined as those that threaten the well-being or life span of a man.
 
What are the causes and risks associated with prostate cancer?
 
Age is one of the major risk factors in getting prostate cancer. The diagnosis of prostate cancer is rare before age 40 but increases dramatically thereafter. It is estimated that one in 55 men between the ages of 40 and 59 will be diagnosed with prostate cancer. 
 
This incidence climbs almost to one in six for men between ages 60 and 79. This association is also reflected in mortality as prostate cancer accounts for about 10 percent of cancer-related deaths in men between the ages of 60 and 79 and nearly 25 percent in those over the age of 80.
 
Genetic predisposition, diet and environmental factors are the other risk factors in getting prostate cancer. Worldwide, prostate cancer ranks third in cancer incidence and sixth in cancer mortality among men. The incidence is low in Asian countries like Japan but the incidence is slowly rising. The incidence is higher in North America and Northern Europe. 
 
There are also ethnic determinants of risk. Blacks are in the highest risk group. The incidence in Caucasian and Asian men is slightly more than half that of blacks. Men with a family history of prostate cancer are at an increased risk of developing the disease. 
 
The risk correlates with the number of first-degree relatives (father, brother or uncle)
affected by prostate cancer and the age at onset. Men with a family history of disease may have a risk of developing prostate cancer 2 to 11 times greater than men without a family history of prostate cancer.
 
Can dietary intake influence the risk of prostate cancer?
 
There is evidence demonstrating that prostate cancer is more common in men with a high intake of fat in their diets. The worldwide difference in prostate cancer incidence may be associated with dietary intake of soy proteins. 
 
In Asian countries such as Japan and the Republic of Korea where prostate cancer incidence and mortality are just a fraction of that in North America, soy consumption in the form of tofu, soymilk and miso is up to 90 times higher than that consumed in the United States. There are some suggestions that the worldwide differences in prostate cancer incidence may also be explained by the high intake of green tea by residents of Asia. 
 
The intake of other certain dietary factors may also reduce the risk of developing prostate cancer. Such substances include lycopene and selenium. Cooked tomatoes are rich sources of lycopene. Researchers found that men ingesting two or more servings of tomato sauce per week had a 36 percent reduction in cancer risk compared to those who did not. 
 
Selenium intake has also been reported to lower prostate cancer risk. Men who took Selenium had a 63 percent reduction in prostate cancer incidence.
 
Can prostate cancer be prevented?
 
There is controversy about true prevention. Some physicians believe that antiandrogen drugs, such as finasteride and dutasteride, can prevent prostate cancer. 
 
However, others are skeptical, and some believe that antiandrogens can only slow the progression of well-differentiated elements but may allow higher-grade elements to emerge as the dominant elements in the tumor. 
 
Some physicians believe that general health measures might reduce the risk of prostate cancer, such as eating a healthy diet, being physically active and visiting the doctor on a regular basis. 
 
Clinical studies are ongoing which are testing the ability of some antioxidants, such as vitamin E and selenium to prevent prostate cancer.
 
Can vasectomy cause prostate cancer?
 
The correlation of vasectomy and prostate cancer risk remains controversial. Although some studies have suggested that men who have undergone a vasectomy are at an increased risk of developing prostate cancer, many other studies have failed to show such a correlation.
 
What are the symptoms of prostate cancer?
 
Early prostate cancer often causes no symptoms. When symptoms do occur, they may be associated with difficulties initiating urination, poor urinary flow, straining, pain when passing urine, frequency and urgency of urination. 
 
Occasionally, patients may also have blood in the urine or semen; painful ejaculation; general pain in the lower back, hips or upper thighs; loss of appetite and/or weight; and persistent bone pain.
 
How is prostate cancer diagnosed?
 
Digital rectal examination (DRE) and prostate specific antigen (PSA) are used for prostate cancer detection. In most western countries, it is recommended for healthy men over the age of 50 to consider prostate cancer screening with a DRE and PSA test. 
 
The rectal examination is performed with the man lying on his side or with his knees drawn up to his chest on the examining table. The physician inserts a gloved finger into the rectum and examines the prostate gland. 
 
The PSA test is usually performed in addition to DRE and increases the likelihood of prostate cancer detection. PSA is a blood test which can be performed in a clinical laboratory, hospital or physician's office and requires no special preparation on the part of the patient. Ideally, the test should be taken with the patient abstaining from sexual activity for two days prior to having a PSA test.
 
What is PSA?
 
Small amount of PSA escapes from a healthy prostate into the bloodstream, but larger amounts of PSA to leak into the blood in prostatitis and prostate cancer. Non-cancerous enlargement of the prostate, otherwise known as BPH is the commonest cause of elevation of PSA.
 
 Inflammation of the prostate, called prostatitis, is another common cause of PSA elevation. Some refinements have been made in the PSA blood test in an attempt to determine more accurately who has prostate cancer and who has false positive PSA elevations caused by other conditions like BPH. 
 
These refinements include PSA density, PSA velocity, PSA age-specific reference ranges and use of free-to-total PSA ratios. Such refinements may increase the ability to detect cancer and these should be discussed with your physician. 
 
It has been shown that only 18 to 30 percent of men with PSA values between 4 and 10 ng/ml have prostate cancer. This number rises to approximately 42 to 70 percent for those men whose PSA values exceeding 10 ng/ml.
 
What is prostate biopsy?
 
Prostate biopsy is necessary to determine whether the PSA elevation is due to cancer. It is best performed under transrectal ultrasound guidance using a spring-loaded biopsy device. 
 
The patient is prepared with an enema and an antibiotic. The lubricated ultrasound probe is inserted into the rectum.
 
Patients are positioned on their side for this procedure. The physician will first image the prostate using ultrasound noting the prostate glands size. Local anaesthesia is injected through a long fine needle that is passed through the probe to reduce pain. 
 
The physician performs multiple biopsies of the prostate gland. Generally, 10 to 12 (or more, depending upon the size of the prostate gland and the prior PSA and biopsy history of the patient) biopsies will be performed.
 
The entire procedure takes 20 to 30 minutes. The biopsy tissue taken will then be examined by a pathologist (a physician who specializes in examining human tissue to determine whether it is normal or diseased).
 
The transrectal ultrasound guided prostate biopsy is usually well tolerated. Blood in the ejaculate (hematospermia) and blood in the urine occur in most patients which is self limiting. 
 
High fever is rare, occurring in only 1 to 2 percent of patients. The antibiotic is continued for at least 48 hours after the biopsy procedure.
 
How is prostate cancer graded?
 
The grade indicates the tumor's degree of aggressiveness—how quickly it is likely to grow and spread.
 
The Gleason grading system is the most widely used system. In this system, the majority tumor pattern is assigned a score from 1 to 5 and the minority pattern is similarly assigned a score, using the same scale. 
 
The majority and minority scores are added together to give a Gleason sum ranging between 2 and 10. 
 
Scores of 2 to 4 designate low aggressiveness, 5 to 6 mildly aggressive, 7 moderately aggressive and scores of 8 to 10 highly aggressive.
 
Why is prostate cancer staged?
 
Once prostate cancer has been diagnosed by a prostate biopsy, the physician must stage the disease to determine the extent of the cancer (i.e., the "T" stage) and whether it has spread beyond the prostate gland to the surrounding tissues, the seminal vesicles, the lymph nodes and/or the bones.
 
This is determined by imaging techniques such as CT scan, MRI and bone scan.
 
Are all prostate cancers the same?
 
Prostate cancer represents a spectrum of disease. Although some cancers may grow so slowly that treatment may not be needed, others are a threat to life. 
 
The need for treatment should be based on the stage and grade of the cancer as well as the age and health of the patient. By combining many types of information such as PSA level, clinical stage and Gleason score, patients can be advised of the likely aggressiveness of their cancer and the need for and types of treatment available. 
 
However, the longer the patient's life expectancy, the more uncertain the prediction becomes, as most prostate cancers progress with time.
 
What are the current treatment options for men with localized prostate cancer?
 
Watchful Wait or Expectant Management
 
Prostate cancer is often a slowly progressive disease, and many men with prostate cancer will die from causes other than prostate cancer.
 
 In general, older men with a limited life expectancy and those with low-grade, small-volume disease may benefit from expectant management, and a therapeutic intervention should be reserved for those demonstrating clinical progression.
 
Surgery (Radical Prostatectomy)
 
Surgery remains the primary option for many men with localized prostate cancer. Compared to other treatment methods such as radiotherapy and cryotherapy, a radical prostatectomy has an advantage of providing accurate local staging as well as assessment of pelvic lymph nodes through a detailed pathologic analysis. 
 
For patients with prostate cancer pathologically confined to the prostate, the chance of cure with surgery alone at 10 years (undetectable PSA) is more than 90 percent. 
 
The risk of cancer progression in men with extracapsular disease (cancer beyond the capsule of the prostate gland) and/or positive surgical margins is much higher ranging from 30 to 50 percent, and these patients may benefit from additional therapy such as external radiotherapy or hormonal treatment. 
 
The main complications of radical prostatectomy are urinary incontinence and erectile dysfunction.
 
 
Open Radical Prostatectomy: In radical prostatectomy, the entire prostate gland is removed as a unit with the seminal vesicles. 
 
There are several different surgical techniques in performing a radical prostatectomy. The retropubic approach utilizes a midline incision below the umbilicus and allows
simultaneous access to the prostate and pelvic lymph nodes. The retropubic approach remains the most popular technique used by practicing urologists.
 
 The radical surgery can also be done in a perineal approach. The prostate is removed through a small semi-lunar incision in the perineum.
 
 This approach is associated with less blood loss and a shorter hospital stay and faster overall recovery.
 
Robotic Assisted Laparoscopic Radical Prostatectomy: With recent advances in minimally invasive surgery and computer technology, the prostate gland can now be removed through a small one-to-two-inch incision in the patient's abdomen.
 
 Introduced in 2001, robotic prostatectomy utilizes a surgical robotic system—named the da Vinci Robot (Intuitive Surgical, Inc., Sunnyvale, CA)—to remove the prostate gland through laparoscopic access in which surgeons make keyhole openings rather than a single 6 to 8-inch midline incision. 
 
The small skin incisions result in less pain, less blood
loss, faster catheter removal and a shorter hospital stay, with some patients returning to work as early as two weeks after the procedure.
 
Radiotherapy
 
Traditionally, radiotherapy has been reserved for an elderly population (over 70 years), men with locally advanced prostate cancer, and those with a short life expectancy (less than 15 years).
 
Recent retrospective studies have shown that radiotherapy and surgery can offer comparable long-term outcomes up to 10 years. 
 
Radiotherapy for prostate cancer can be divided into two modalities: external
beam radiation (EBRT) and brachytherapy (PB). 
 
In external beam radiotherapy, a small amount of radiation is delivered incrementally to the prostate over a course of 6 to 7 weeks. The total radiation dose received is usually over 70 Gy. 
 
Currently, three-dimensional conformal radiotherapy (3DCRT) or
intensity-modulated radiotherapy (IMRT) is used to deliver high-dose radiation to the prostate while minimizing toxicity to the surrounding normal structures such as the bladder and rectum.
 
Prostate brachytherapy is another method in which radioactive seeds are implanted directly into the prostate. The seeds are delivered percutaneously into the prostate via the specially designed needles under real time ultrasound imaging. 
 
Both low-dose rate (but high-dose) permanent prostate seeds and high dose rate (HDR) temporary implants can be used to treat the gland successfully.
 
The main side effects of radiotherapy can result in urinary and bowel dysfunction. The incidence of erectile dysfunction also appears to be similar to that of surgery, ranging in 20 to 50%.
 
Hormonal treatment can also be used before or after radiotherapy. For patients who are at high risk for cancer recurrence, a prolonged use of androgen ablation (up to 3 years) combined with EBRT has resulted in improved survival compared to EBRT alone.
 
Should radiation therapy be used as treatment following surgical removal of the prostate (prostatectomy)?
 
External beam radiation therapy (EBRT) may be used following prostatectomy when there is concern that cancer may remain in the region of the prostate. 
 
The use of radiation in this setting to destroy residual cancer has been sporadic for many years but only in the past five to 10 years has this approach started to gain widespread acceptance. The possibility of success with radiation following prostatectomy depends on the likelihood that any remaining cancer is confined to the region of the prostate where radiation is aimed. 
 
Therefore, the success rate varies widely depending on the presentation at the time treatment is contemplated.
 
How successful is radiation therapy in the treatment of metastatic cancer?
 
Radiation is often an effective treatment for preventing or managing symptoms of prostate cancer that has spread.
 
External beam radiation therapy is typically very helpful in decreasing or relieving pain
related to prostate cancer that has spread to the bones. A short course of therapy usually no longer than two weeks is sufficient in most cases. 
 
In other cases, radiation may be used to prevent debilitating symptoms related to the uncontrolled spread of cancer near critical organs or tissues.
 
Is chemotherapy effective in prostate cancer?
 
Although surgery and radiation therapy remove, destroy or damage cancer cells in a specific area, chemotherapy works throughout the body. Chemotherapy can destroy cancer cells that have metastasized, or spread to parts of the body far away from the primary (original) tumor.
 
Chemotherapy is the use of specific drugs that can destroy cancer cells. The drugs circulate throughout the body in the bloodstream and can kill any rapidly growing cells, including potentially non-cancerous ones.
 
Chemotherapy drugs are carefully controlled in both dosage and frequency so that cancer cells are destroyed while the risk to healthy cells is minimized. Often, it is not the primary therapy for prostate cancer patients, but may be used when prostate cancer has spread outside of the prostate gland or in combination with other therapies.
 
What are some of the side effects of chemotherapy?
 
Common side effects of chemotherapy depend on the type of drug used, dosage and length of treatment. The most common side effects are fatigue, nausea and vomiting, diarrhea, hair loss and increased susceptibility to infection. 
 
To minimize the side effects, chemotherapy drugs are carefully monitored according to the amount and number of times they are administered by your physician.
 
Supportive medication is also given to further help offset the side effects caused by the drugs. For instance, new drugs to prevent nausea and vomiting can minimize these side effects. 
 
Most side effects disappear once chemotherapy is stopped.
 
How is chemotherapy administered?
 
The drugs used for chemotherapy can be administered directly into a vein while others may be taken orally. Some of the drugs must be given in the doctor's office or clinic; others can be administered while the patient is at home. Hospitalization is rarely needed unless side effects occur.
 
What is hormonal treatment of prostate cancer?
 
Androgens are male sex hormones responsible for characteristics such as facial hair, a deepened voice and increased muscle bulk. They come from two sources: the testicles (accounting for 90 to 95 percent of the male hormones) and the adrenal glands that produce several other androgens (accounting for 5 to 10 percent of male hormones).
 
When the prostate cancer is advanced, spreading to other parts of the body, treatment shifts to reducing the testosterone (male hormone) that feeds the prostate and its tumors. By depleting it, hormone therapy reduces symptoms and prevents further growth. 
 
But while hormonal manipulation causes prostate cancer to shrink in 85 to 90 percent of advanced prostate cancer patients, it does not cure the disease. 
 
In addition, the effects only last between 24 and 36 months. Androgen deprivation is usually achieved by either surgery or medication, in what is commonly referred to as monotherapy because one method is used. 
 
Testosterone can be reduced by removing the testes during a bilateral orchiectomy.
 
The other commonly used option, however, is chemical castration — injecting synthetic LH-RH agonists (stimulates an action) or antagonists (blocks an action) into the body every three to four months to suppress the natural production of testosterone. 
 
A second option focuses on interfering with the effects of other adrenal hormones in addition to testicular testosterone. Referred to as complete androgen blockade (CAB), this treatment choice combines an orchiectomy or LH-RH antagonist with anti-androgens, drugs that block the effects of adrenal gland hormones.
 
What can be expected after hormone therapy for prostate cancer?
 
While hormonal therapy can put your cancer in check, there are unpleasant side effects: nausea and vomiting, hot flashes, anemia, lethargy, osteoporosis, swollen and tender breasts and erectile dysfunction.