Prostate Cancer
Prostate cancer is the most common malignancy diagnosed in North American men (other than skin cancer). One out of every 6 to 7 men will develop the disease during his lifetime. The exact cause of prostate cancer is still unknown; however, a combination of genetic, nutritional and environmental factors appear to play a role in its development. Typically, prostate cancer begins in the outer part of the gland. When confined within the prostate, it is called localized prostate cancer. Prostate cancer may behave in many different ways in different men. It may be relatively slow growing, but it may also be more aggressive in its behavior with a tendency to metastasize or spread to the lymph nodes, bones, or other parts of the body. It is this latter form of prostate cancer that is life threatening.
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Prostate Cancer / Early Detection and Diagnosis
Early Detection and Diagnosis
The best way to diagnose prostate cancer involves a digital rectal exam and a prostate specific antigen (PSA) blood test. Patients with localized cancer rarely have any symptoms. New markers for the early detection of prostate cancer are under development and study.
Digital Rectal Exam
The Digital Rectal Examination (DRE) may detect a cancer and judge whether it is confined to the prostate. The Prostate lies in front of the rectum; therefore, the doctor can feel the prostate by inserting a gloved, lubricated finger into the rectum. The DRE is not always accurate, as many prostate cancers are situated deeper in the gland or are too small for detection, and not all ‘lumps’ on the prostate are cancerous. Once a cancer can be felt as a lump, it is considered to be at a more advanced stage than when it is detected only by a PSA blood test.
Prostate-Specific Antigen (PSA)
Prostate-specific antigen (PSA) is a protein produced by both normal and cancerous prostate cells. When prostate cancer grows or when other prostate diseases are present, the amount of PSA in the blood may increase.
A PSA test is generally said to be in the normal range when it is reported to be between 0 and 2.5 nanograms per milliliter (sometimes abbreviated as ng/mL on the lab report) and not increasing over time. PSA may be elevated because of a non-cancerous condition, such as enlargement or inflammation of the prostate.
If the results are in the high range (or have increased since a prior test), your physician may suggest a biopsy, which is the only test to actually diagnose prostate cancer.
Percent-Free PSA Ratio
Percent-free PSA ratio is a blood test that measures how much PSA circulates by itself (unbound) in the blood, and how much is bound together with other blood proteins. If PSA results are elevated and percent-free PSA ratio is low (10% or less), then prostate cancer is more likely to be present. If this is the case, a biopsy may be needed.
Ultrasound
Transrectal ultrasonography (TRUS) is the most direct way to see the prostate gland. Ultrasound provides an image that can be used to measure the size of the prostate and sometimes can detect suspicious tissue. TRUS is almost always done in combination with a biopsy. When a needle biopsy of the prostate is performed, it is always done under ultrasound guidance.
Biopsy
A prostate biopsy removes small amounts of tissue to examine under a microscope to determine whether cancer is present. Typically between 6 and 12 biopsies are taken from the prostate using a core biopsy needle. By examining tissue samples under a microscope, the diagnosis of cancer can be established. When a tumor is discovered, it is classified, under the microscope, into a category called tumor ‘grade’.
Last update: September 14, 2020
Prostate Cancer / Grading and Staging
Grading and Staging
Gleason System
What is the Gleason system for grading prostate cancer?
A pathologist named Gleason described the grading system for prostate cancer. The Gleason grade reflects how aggressively the prostate cancer is likely to behave.
The pathologist will look at the biopsied prostate tissue under a microscope to compare the cancerous tissue to normal prostate tissue.
How are the Grades interpreted?
If the cancerous cells appear to resemble the normal prostate tissue, they are said to be very well differentiated and considered to be Gleason grade 1 to 3. This means that the tumor is not expected to be fast growing. On the other hand, if the cells in question look fairly irregular and different from the normal prostate cells, then they are poorly differentiated, and are assigned a Gleason grade of 4 to 5. (It is rare to see a Gleason grade 1 or 2 cancer.)
The prostate cancer tissue is often made up of areas that have different grades; therefore, the pathologist will closely examine the areas that make up the largest portion of the tissue. Gleason grades are given to the two most commonly occurring patterns of cells. They will describe and rate the cancer cells in 2 ways: (1) how the cancer cells look and (2) how they are arranged together.
Once the two grades have been assigned, a Gleason score is determined. This is done by adding together the two Gleason grades. The resulting Gleason score will be a number from 2 to 10. (i.e., 3 + 4 = 7/10)
The biopsy also can give important information about whether the cancer involves small nerves within the gland (perineural invasion) and an indication of how extensive the cancer might be within the gland (number of cores positive).
Stage
Stage refers to the amount of cancer in the prostate, and whether the cancer has spread outside the gland. There are several tests that may be useful in determining tumor stage, but for most men no such tests are required. This is because the chance of finding cancer elsewhere in the body is so low for most men with early cancers of the prostate that such tests are not warranted.
Prostate Cancer / Grading and Staging / Diagnostic Tests for Staging
Diagnostic Tests for Staging
CT Scan
Computed Tomographic scan (CT scan) is an x-ray procedure that gives cross-sectional images of the body. The CT scan may help detect lymph nodes in the pelvis that are enlarged because of cancer. Generally, a CT scan is done only if the cancer is high risk (high PSA, high Gleason score, or abnormal findings on DRE).
Magnetic Resonance Imaging
Magnetic Resonance Imaging (MRI) is similar to a CT scan except that it uses magnetic fields instead of x-rays to create internal pictures of your body. MRI is better than CT at imaging the prostate, but has limited usefulness for distinguishing benign from cancerous areas. Standard MRI, therefore, has limited usefulness for determining the extent of disease. Research is being carried out to determine whether MRI techniques can “see” cancer better. Currently, there is no established role for MRI in prostate cancer.
Bone Scan
A test called a Bone Scan is performed to see if the cancer cells have spread to the skeleton. For this test, a radiology technician injects a small amount of radioactive material into the patient's bloodstream and the patient returns 3 hours later for the scan. The radioactive material collects in the area where there are bone-activating cells. A scanner then pinpoints the areas where the radioactive material collects, so these areas can be evaluated for possible sites of bone metastasis. This study is limited to those with high-risk disease (high PSA, high Gleason score, or abnormal findings on DRE).
Lymph Node Dissection
The lymph nodes are often the first location where prostate cancer spreads. The physician can usually estimate the likelihood that cancer has spread to the lymph nodes based on the rectal examination, PSA, and biopsy results; and by using a published nomogram. If there is a high likelihood that the cancer has spread to the lymph nodes, the physician may elect to surgically sample, remove and examine the lymph nodes under a microscope. This is often done at the time of radical prostatectomy in intermediate and high-risk cases. Special imaging techniques are being developed to study lymph nodes without having to surgically remove them.
Prostate Cancer / Grading and Staging / Clinical Stage
Clinical Stage
Clinical tumor stage refers to whether or not the tumor can be palpated or felt on exam and whether it may have spread to lymph nodes or other organs. Clinical stage is based on all information available prior to any treatment and designated by the TNM system. The TNM staging system describes the extent of the primary tumor (T), the absence or presence of metastasis to nearby lymph nodes or glands (N), and the absence or presence of distant metastasis (M).
Prostate Cancer / Grading and Staging / Predictive Models
Predictive Models
There are a number of models that allow doctors to assist patients in predicting the risk of prostate cancer recurrence following therapy. These nomograms (mathematical models) are used to predict the risk of PSA failure after treatment and may help to educate men and their families to the risk of suffering PSA failure after surgery or radiation therapy. PSA failure refers to a rising PSA after treatment.
It should be remembered that these models have accuracy rates somewhere in the 75% range. While these models are useful during discussions about treatments of prostate cancer, models should be placed into perspective by the patient and physician with regard to the individual patient’s overall health status and personal preferences for treatment.
Discussing cancer treatment options are perplexing. Patient’s anxieties can be relieved by understanding the high chances of overall success from either radiation therapy or surgical treatment options. Urologists and radiation treatment specialists have been early pioneers in the use of mathematical models for educating patients. Any questions that patients may have about the use of these models should be brought up during their discussion with their doctors.
Prostate Cancer / Treatments
Treatments
Prostate cancer treatment depends upon the type of cancer, the absence or presence of metastasis, the patient’s age, the patient’s general health status, life expectancy and any prior prostate treatments the patient may have undergone.
The three standard therapies for men with organ-confined prostate cancer are:
To date, no study has directly compared these three options. This fact makes it difficult to compare outcomes in men treated with either surgery or radiation.
Other treatments include:
Prostate Cancer / Treatments / Active Surveillance
Active Surveillance
Active surveillance is considered a treatment option if a cancer is not causing any symptoms and is expected to grow slowly. In the past this approach was mainly suggested to elderly men, or men with serious health problems; however, younger men have started to consider this treatment option. Since prostate cancer often spreads very slowly, many men who have the disease may never require treatment. In many men, it is a means of delaying or deferring therapy and potential quality of life changes associated with current treatment options. Typically, patients on an active surveillance program undergo regular PSA measurements and periodic prostate biopsies to ensure that the cancer is not becoming more aggressive. If there is a change in the prostate cancer then the patient can make a decision to undergo active treatment with either surgery or radiation. Approximately 30% of cancers will progress within 5 years. The intent of active surveillance is curative.
Prostate Cancer / Treatments / Surgery (Prostatectomy)
Surgery (Prostatectomy)
Surgical treatment for prostate cancer involves removing the entire prostate and seminal vesicles. When the cancer is confined within the tissues, surgery alone can usually cure localized prostate cancer. The PSA level in the blood should fall to undetectable levels after prostatectomy.
There are three main types of prostatectomy:
- Retropubic Prostatectomy (RP)
- Nerve-Sparing Prostatectomy
- Robotic Assisted Laparoscopic Prostatectomy (RALP)
Retropubic Prostatectomy (RP) is a procedure where the surgeon makes a skin incision in the lower abdomen (four finger breadths below the umbilicus to just above the pubic area). If indicated, a pelvic lymph node dissection (PLND) is performed prior to removal of the prostate. The lymph node dissection is a staging procedure performed to more accurately determine if prostate cancer is present in the lymph nodes.
Following the PLND, the prostate is removed from between the bladder and the urethra. When it is possible, the surgeon carefully spares the small bundles of nerves located on either side of the prostate gland that are needed for erections (‘nerve sparing surgery’). With the prostate removed, the bladder opening is sewn to the urethra. A catheter is placed through the penis and remains in place while the tissues heal. Patients undergoing surgery can expect a hospital stay of 1 to 2 days. The catheter and staples are removed in the clinic approximately 7 to 10 days later.
Nerve-Sparing Prostatectomy is performed if there is no indication of tumor extension close to the nerves surrounding the prostate, called the neurovascular bundle. A unilateral nerve-sparing procedure will save the nerves on one side of the prostate. A bilateral nerve-sparing procedure saves the entire neurovascular bundle or the nerves on both sides of the prostate. Patients with locally advanced tumors are not offered nerve-sparing surgery because of concerns about leaving cancer at the margins of the prostate capsule. Occasionally there are technical issues (eg. scarring, unusual blood vessel anatomy, large prostates) that make nerve sparing difficult or impossible. The surgeon cannot predict these factors prior to operating. Men who are younger than age 60, and those who have the highest levels of pre-operative sexual function usually have the best outcomes in terms of potency.
Robotic Assisted Laparoscopic Prostatectomy (RALP) is a minimally invasive technique used to remove the prostate in patients with prostate cancer. The surgeon performs the procedure through six small incisions spread in a fan shape across the upper abdomen. Surgical fields are viewed with the use of a laparoscope (a camera inserted through one of the incisions). Surgeons performing LRP at Vancouver General Hospital use a robotic surgical assist device called the “da Vinci® Surgical Robot”.
There are two main components to the robotic system. A surgeon’s console, where the operating surgeon sits and controls the instruments and the robotic arms, which are at the patient’s side and hold the camera and instruments used during the operation. The da Vinci® robot allows surgeons to perform surgical procedures with greater ease and precision.
Patients considering surgical treatment for their prostate cancer have common concerns: cure, recovery, urinary continence, and sexual function.
Return of urinary continence and sexual function following both the open and LRP are similar.
Prostate Cancer / Treatments / Surgery (Prostatectomy) / Anesthesia
Anesthesia
The decision as to which type of anesthesia to employ during surgery is made between the patient and the anesthesiologist. Typically, patients and their families meet with the anesthesia service in the days prior to surgery to discuss their general medical health, previous anesthetic experiences and specific anesthetic related concerns.
Three general categories of anesthesia are used for RP: general, regional or combination (general and regional). Multiple factors go into the decision as to which technique to use: patient preference, patient anatomy, medical history and post¬operative pain control needs. These issues are addressed with each patient during the pre-operative anesthesia visit. The vast majority of patients at VGH undergo general anesthesia.
Prostate Cancer / Treatments / Surgery (Prostatectomy) / Treatment Side Effects
Treatment Side Effects
The surgical risks associated with all radical prostatectomy techniques (RP and RALP) are similar to those of any major surgery. The level of risk depends in large part on the patient's overall health and age. Rare risks include cardiac or pulmonary events, blood clots or injuries to structures surrounding the prostate. The primary side effects unique to a radical prostatectomy are incontinence and impotence.
Urinary Control: Following surgery, significant bladder control often returns within 12 weeks and continues to improve over 12 to 24 months. Return of function is often dependent on pre-operative urine control and patient weight. For example, men with larger abdomens (that press down on bladder) may have more problems with return of continence. Approximately 1 to 2 percent of patients will have persistent, severe post¬operative incontinence. This group of patients will wear pads, take medication or undergo further procedures to treat this side effect. Mild stress incontinence, which is passing a small amount of urine when coughing, laughing or sneezing, does occur following surgery. Some men may choose to wear pads to protect themselves from unexpected leakage. However, the majority of men do not consider this to be a major issue.
Of patients who undergo a prostatectomy, over 90 percent have excellent urinary control and require no pads or other means of protection.
Sexual Function: Sexual dysfunction is a common problem in both men and women. Sexual problems become progressively more common with aging, heart disease, high cholesterol and diabetes. Prostate cancer and the treatment of prostate cancer can have a significant impact on sexual function. At diagnosis, we assess baseline sexual function. We provide counseling to the patient and his partner about anticipated changes in sexual function and try to predict the likelihood of preserving and recovering sexual function after prostate cancer treatment.
Prostate Cancer / Treatments / Surgery (Prostatectomy) / Potency Recovery
Potency Recovery
Several studies have shown that even with bilateral nerve-sparing surgery, it may take up to 18 to 24 months before a patient recovers reasonable erections. However, major gains are usually made between 6 to 18 months. There are several potential explanations for this time delay: transient nerve injury, postoperative psychological issues and a history of infrequent and non-rigid erections, which affect the flow of oxygen to and the subsequent health of penile tissues.
The delay in the return of potency can be improved by several approaches:
- by employing a careful surgical technique, one is able to minimize potential trauma to the nerves.
- by providing a comprehensive preoperative counseling program for the patient and his partner, one is able to address postoperative concerns and minimize the psychological impacts of surgery.
- by providing early, pharmacologic erections with the drugs listed below, one can avoid long-term penile tissue damage, thus expediting the return of spontaneous erectile function.
We recommend that, within the first 2 weeks after catheter removal, all patients who have undergone an RP should begin self stimulation to enhance eventual recovery of potency. Oral agents (Viagra®, Levitra® or Cialis®) are prescribed to enhance the flow of oxygen to penile tissue. The most common side effects are headache (20 percent), flushing (8 percent), visual disturbance (6 percent) and nasal congestion (6 percent). We ask patients to attempt to have at least 2 to 3 erections per week in the months after surgery in order to maximize post-operative recovery.
The successful recovery of erectile function is highly dependent on the patient and his partner’s education about treatment-related sexual problems. Open sexual communication between partners is essential. Other issues, such as loss of sexual desire, difficulty reaching orgasm, ejaculatory problems or sexual pain also should be addressed. Finally, reproductive health, fertility issues and sperm banking counseling are an integral part of our sexual health rehabilitation program.
Prostate Cancer / Treatments / Surgery (Prostatectomy) / FAQ for Radical Prostatectomy
FAQ for Radical Prostatectomy
Please see the FAQ for Radical Prostatectomy page.
Prostate Cancer / Treatments / Radiation Treatment
Radiation Treatment
Radiation therapy for prostate cancer is administered by our radiation oncology colleagues at BC Cancer Agency. www.bccancer.bc.ca/our-services/services/radiation-therapy
There are two types of radiation treatment available to prostate cancer patients: External Beam Radiotherapy (EBRT) and Brachytherapy.
External Beam Radiotherapy Therapy has been in medically-effective practice for longer than Brachytherapy. This treatment is often simply referred to as Radiotherapy. The goal of treatment is to irradiate a targeted area with as much energy as possible, while avoiding the neighboring organs. Intensity Modulated Radiation Therapy (IMRT), and 3 Dimensional Conformal Radiation Therapy (3D-CRT) are newer versions of EBRT that better achieve this goal. Proton Beam Therapy is becoming a more widely accepted treatment for prostate cancer, while Neutron Beam Therapy is still in the experimental stages.
How Does Radiation Therapy Work On Prostate Cancer?
Radiation is used as a prostate cancer treatment because high energy waves damage the DNA of cells. If a cell divides prior to repairing the damage, the cell will die. Since cancerous cells divide more rapidly than healthy cells, carefully aimed energy will cause their destruction; however, prostate cancer radiation treatment will last over a period of 5 to 9 weeks. During this process, the healthy cells that are repeatedly exposed will be unable to repair the extensive damage. Therefore, the precise aiming of the beam is crucial to the success of the treatment and the avoidance of side effects.
How Do These Radiation Treatments Differ From One Another?
Prostate cancer radiation treatment can be divided into three categories based on the high-energy wave they use: EBRT, IMRT, and 3D-CRT which accelerates subatomic particles called electrons to generate waves of high energy photon radiation. Proton beams use a subatomic particle called protons. Neutron Beam Therapy uses the subatomic particles called neutrons. To continue reading about the different types of subatomic particles, go to the Tools section.
The History Of Radiation Therapy
Prostate cancer radiation treatment has been used in Canada since 1915. The first radiotherapy used radium applicators positioned adjacent to the prostate gland; unfortunately, this technique resulted in significant morbidity. The next technique in radiotherapy used electron beam X-rays; however, these X-rays could not penetrate deeply enough to irradiate the affected tissue. The X-rays were used mainly for palliative care because they also caused skin cancer. After World War II, doctors were able to use megavoltage in prostate cancer treatment. They used radioactive isotopes from Cobalt 60, but by the 1980’s, radiation oncologists began using the linear accelerator, which increased the speed of particles and allowed for the most process aiming of the beam.
Fractionated Prostate Cancer Radiation Treatment
External beam radiation is sometimes called Fractionated, meaning that small doses are given over a long period of time. Patients receive radiotherapy once a day, Monday through Friday over 5-9 weeks, depending on the patient. Normal prostate cells can repair the damage of a small amount of radiation fairly quickly. Cancerous cells cannot. Receiving a small dose everyday helps to minimize the damage sustained by the healthy cells of the surrounding organs. Giving patients the weekend off helps their body to recover enough to withstand the next five days of treatment.
Prostate Cancer / Treatments / Radiation Treatment / Brachytherapy
Brachytherapy
In the 1960’s, the permanent insertion of radioactive material into the prostate gland developed. Doctors tried the interstitial insertion of gold -198 or Iodine - 125 seeds into the prostate gland in conjunction with EBRT. Unfortunately, the success of these techniques was poor due to the inability to see the prostate gland and the surrounding organs. Not until around 1980’s, when doctors began to use a transperineal needle temple, transperineal needles, and the transrectal ultrasound, did Brachytherapy become a viable prostate cancer treatment.
Types Of Prostate Brachytherapy
There are two types of Brachytherapy that are used in the treatment of prostate cancer: Permanent Low Dose Radiation (LDR) and Temporary High Dose Radiation (HDR).
LDR Brachytherapy uses iodine -125 and palladium -103 stored in titanium cases, usually referred to as Brachytherapy Seeds. As the name Permanent Brachytherapy suggest, the seeds are permanently left inside the prostate gland. Over the course of their radioactive lives, the seeds will continuously emit low levels of radiation.
HDR Brachytherapy uses a single radioactive seed made of iridium -194, which is sometimes referred to as an iridium wire. Soft flexible plastic catheters are inserted through the perineum, and into the prostate gland. HDR Brachytherapy entails an overnight stay in the hospital, during which a patient undergoes two or three treatments with the wire through each catheter.
Prostate Cancer / Treatments / Drug Therapies for Advanced or Metastatic Prostate Cancer
Drug Therapies for Advanced or Metastatic Prostate Cancer
Androgen Deprivation Therapy (ADT) is usually recommended first for men with advanced or metastatic prostate cancer.
What Is Androgen Deprivation Therapy?
Male hormones (androgens, the most common of which is testosterone) fuel the growth of prostate cancer. Treatments that decrease the body's levels of androgens, or ADT, decrease the size of prostate cancer. ADT can be done by taking medicines that interfere with androgens, or by having surgery to remove the testicles (called an orchiectomy). In Canada, medical treatment is usually preferred to surgery for advanced disease.
Examples of the medicines used in ADT include:
- GnRH agonists - GnRH agonists are medicines that temporarily "turn off" the testicles' production of male hormones (androgens). This starves the cancer cells, causing the prostate to shrink. GnRH agonists are given as a shot every three to six months and include leuprolide (Lupron) and goserelin (Zoladex).
- Combined androgen blockade (CAB) - Some doctors recommend a second medicine, called an antiandrogen, in addition to the GnRH agonist. Examples of antiandrogens include flutamide (Eulexin), enzalutamide (Xtandi) and bicalutamide (Casodex).
Side Effects Of Androgen Deprivation Therapy
The side effects of ADT are related to the lowered levels of male hormones and include:
- Decreased libido (sex drive), and difficulties with erection (erectile dysfunction)
- Hot flashes
- Enlargement of the breasts (called gynecomastia)
- Loss of muscle and an increase in body fat
- Thinning and weakening of the bones (called osteoporosis), which can increase the risk of bone fractures
- An increased risk of developing type 2 diabetes
- An increased risk of developing or worsening coronary heart disease, which can lead to heart attack
Many of these side effects are serious and might seem frightening. Not all men have these side effects. It is important to balance the risk of side effects with the risk of not using androgen deprivation, which could allow your cancer to grow or spread. In most men, the risk of the cancer growing or spreading outweighs the possible risk of side effects. In addition, there are ways to prevent or treat many of these side effects.
When To Start Androgen Deprivation Therapy?
Experts disagree about the best time to start ADT. Many doctors recommend starting it when metastatic prostate cancer is first diagnosed; the hope is that treatment will slow the growth of the cancer, and possibly prolong survival. Others believe that early ADT is not curative and can cause bothersome side effects. Doctors in this group recommend delaying the start of treatment until symptoms of cancer (like bone pain) develop. Discuss the benefits and risks of each approach with your doctor.
Secondary Hormone Therapy
Most men with advanced prostate cancer initially respond well to ADT, but then prostate cancer comes back within two years. At this point, the cancer is termed androgen resistant, meaning that ADT alone is no longer effective. Once this occurs, secondary hormone therapy is usually considered. Even when prostate cancer becomes androgen resistant, some form of ADT is usually continued because at least a portion of the cancer cells might still respond.
Secondary Hormone Therapy can include:
- Stopping the antiandrogen (flutamide, nilutamide, bicalutamide)
- Trying a different type of antiandrogen. Cancer that is resistant to one antiandrogen treatment may not be resistant to another.
- Trying another medicine that blocks the activity of androgen in the body, including estrogen, steroids, or the antifungal medication ketoconazole.
Chemotherapy
Eventually, most men with advanced prostate cancer stop responding to all forms of hormone treatment. This is called castrate-resistant prostate cancer (CRPC). The next step in treatment often includes chemotherapy.
Chemotherapy is a treatment given to slow, or stop, the growth of cancer cells. Most treatments involve a combination of several chemotherapy drugs (called regimens). Most of the drugs are given into the vein (intravenous, IV).
Chemotherapy is not given every day, but instead is given in cycles. A cycle of chemotherapy (which is typically 21 or 28 days) refers to the time it takes to give the treatment and then allow the body to recover from the side effects of the medicines.
Side effects of chemotherapy can include:
- Temporary hair loss
- Nausea and vomiting
- Lowered blood counts, which increase the risk of developing an infection.
Bone Pain Treatment
The bones are a common place for prostate cancer to spread. Androgen deprivation therapy can often control the cancer that has spread to bones.
Men who develop bone pain in one or a few bones as a result of the cancer can be treated with Radiation Therapy to relieve their pain. The radiation is usually given in one or a few visits, similar to having an X-ray. Some people have worsened pain for one to two days immediately after the radiation treatment; however, most people feel partial or complete improvement of pain within a week after treatment.
Emerging Therapies For Treatment Of Castrate-Resistant Prostate Cancer (CRPC)
There are a number of new avenues being explored for the treatment of CRPC, including:
- The Androgen Receptor (AR) axis
CRPC tumours develop compensatory mechanisms during androgen starvation which re-activate the AR and lead to disease progression.
CRPC's are not uniformly hormone refractory, and may remain sensitive to therapies directed against the AR axis. Tumours should not be termed “hormone resistant” or “hormone refractory”. - Angiogenesis
Angiogenesis is the process by which the body generates new blood vessels. New blood vessels are necessary if tumors are to grow and metastasize and are associated with disease progression and a poor prognosis. Inhibiting angiogenesis has been shown to be effective in a number of cancer types. Several anti-angiogenic agents are in late stage trials in CRPC; however, negative results from bevacizumab plus docetaxel reduces likelihood of success of this class. - ET -1 Receptor
Endothelin-1 is produced by prostate epithelia and plays an important role in prostate cancer. Activation of the Endothelin Type A (ETA) receptor by ET-1 promotes cell proliferation and survival ETA blockade has significant effects in CRPC. ETA blockade may have additive ant-tumor effects when used in conjunction with other chemotherapeutics. - Molecular Chaperones
Chaperones are essential to the viability of cells and act as genetic buffers stabilizing the cells to environmental stress such as heat or toxic chemicals (such as chemotherapeutic agents). Molecular Chaperones have several functions which inhibit treatment-induced cell death. Targeting those with roles associated with cancer progression and treatment resistance is an attractive therapeutic strategy as an addition to conventional chemotherapy. - Immune Therapies
Aim to stimulate the immune system to reject or destroy tumours. Promising results have been reported with the cancer vaccine Provenge, and was recently approved by the U.S. Food and Drug Administration (FDA).
Prostate Cancer / Treatments / Cryotherapy
Cryotherapy
Cryotherapy is a relatively new prostate cancer treatment. Also referred to as Cryosurgery and Cryoablation, Prostate Cryotherapy is a minimally invasive surgery capable of using controlled freeze and thaw cycles to destroy the disease.
Cryotherapy’s Role In The Treatment Of Prostate Cancer
Cryotherapy is relatively new, that is, lacking numerous long-term survival rate studies; therefore, cryotherapy is not used as often as radiation therapy as a primary treatment. Cryotherapy, however, is effective in treating cases of prostate cancer that are radioresistant and recur as a result. Some doctors believe that the use of freezing temperatures rather than stronger doses of radiation therapy is more effective for radioresistant prostate cancer.
Prostate cryotherapy works because as cells freeze, ice crystals form inside and around them. The freezing and thawing processes destroy cells through dehydration, drastic changes in the pH levels, or prevention of the flow of red blood cells. Subjecting the prostate gland to freezing temperatures, specifically negative 40 degrees Celsius, also activates an anti-tumor response in the body. An anti-tumor response begins with the production of anti-bodies that work to eradicate the tumor.
Advantages And Disadvantages Of Cryotherapy
Cryotherapy is an effective primary treatment for those who are in the early stages of prostate cancer with low risk for tumor extension. This treatment may also be an excellent alternative for those who are not good candidates for radical prostatectomy. Cryotherapy may be used if EBRT fails and the cancerous prostate cells are deemed radioresistant. Some advantages of include the one day in-hospital treatment, though some patients will stay overnight depending on their general health.
Cryotherapy can also be repeated if it fails to ablate the cancerous tissue during the first round of treatment. Patients for whom treatments fail can also pursue alternatives such as radiation therapy or prostatectomy. Because cryotherapy is minimally invasive, patients experience only minimal, if any, blood loss. One disadvantage is that the long-term data on cryotherapy is limited, due to its newness as mainstream prostate cancer treatment.