Saturday, August 26, 2006

Prostate Cancer

What is the prostate?

The prostate is a small gland that only men have. It is normally about the size of a walnut. The prostate is located underneath the bladder and in front of the rectum. Because the prostate is close to the rectum, it can be felt by a doctor during a digital rectal exam (the part of a physical where the doctor inserts a gloved, lubricated finger into a man's anus). The prostate makes and stores fluid that is part of semen, and this fluid is released from a man's penis during ejaculation. The prostate is signaled to do its job by the male hormone testosterone, which can influence the behavior of the prostate gland and prostate cancer. Nerves to the penis that are important in producing and maintaining an erection run very close to the prostate. The prostate completely encircles the tube that carriers urine from the bladder to the penis, called the urethra.
If the prostate enlarges, it can block the flow of urine from the bladder making it difficult for a man to urinate.
What is prostate cancer?
Prostate cancer happens when cells in the prostate begin to grow out of control and can then invade nearby tissues or spread throughout the body. Large collections of this out of control tissue are called tumors. However, some tumors are not really cancer because they cannot spread or threaten someone's life. These are called benign tumors. The tumors that can spread throughout the body or invade nearby tissues are considered cancer and are called malignant tumors. Usually, prostate cancer is very slow growing. However, sometimes it will grow quickly and spread to nearby lymph nodes. Lymph nodes are small, pea-sized pieces of tissue that filter and clean lymph, a clear liquid waste product. If prostate cancer has spread to your lymph nodes when it is diagnosed, it means that there is higher chance that it has spread to other areas of the body.

Am I at risk for prostate cancer?
Every man over the age of 45 is at risk for prostate cancer. Although prostate cancer can occasionally strike younger men, the risk of getting prostate cancer increases with age and more than 70% of men diagnosed with prostate cancer are over the age of 65. Prostate cancer is the most common cancer that men get in the United States behind skin cancer. It is estimated that there will be 189,000 new cases of prostate cancer and 30,200 deaths from prostate cancer in the year 2002 in the United States.

Although there are several known risk factors for getting prostate cancer, no one knows exactly why one man gets it and another doesn't. Some of the most important risk factors for prostate cancer include age, ethnicity, genetics and diet. Age is generally considered the most important risk factor for prostate cancer. The incidence of prostate cancer rises quickly after the age of 60, and the majority of men will have some form of prostate cancer after the age of 80. One of the sayings about prostate cancer is that older men (over the age of 80) die with prostate cancer not from prostate cancer. This saying means that many older men have microscopic disease that doesn't shorten their life expectancy because the cancer takes a long time to grow and become clinically important. However, this saying is only a generalization; sometimes prostate cancer can grow quickly even in older patients.

Another important risk factor for prostate cancer is ethnicity. No one knows exactly why, but prostate cancer is more common in African-American and Latino men than Caucasian men. African-American men have a 1.6 fold higher chance of getting and dying from prostate cancer than Caucasian men. Asian and Native American men have the lowest chances of getting prostate cancer. Some doctors believe that genetic differences are important in explaining the different rates of prostate cancer between different ethnic groups; however, there is some evidence that differences in diets may be the cause. When Asian men move to Western countries like the United States, their chances of getting prostate cancer rise. Men who live in the United States and Northern Europe have the highest rates of prostate cancer, while men who live in South America, Central America, Africa, and Asia all have much lower chances of developing prostate cancer.
There is some evidence that a man's diet may affect his risk of developing prostate cancer. The most common dietary culprit implicated in raising prostate cancer risk is a high fat diet, particularly a diet high in animal fats. Also, a few studies have suggested that a diet low in vegetables causes an increased risk of prostate cancer. There are a few foods that have been implicated in decreasing prostate cancer risk: a diet high in tomatoes (lycopene) has been suggested as well as diet high in omega-3-fatty acids (oils found in fish like salmon and mackerel). Doctors and scientists aren't in full agreement as to the usefulness of eating these foods when in comes to decreasing prostate cancer risk. Diets high in selenium, vitamin D, and soy have all been suggested to decrease prostate cancer risk; but a these are currently under study and data from large trials is needed before firm recommendations can be given about their use for this purpose.
A family history of prostate cancer increases a man's chances of developing the disease. This increase shows itself when a man has either a father or brothers (or both) with prostate cancer, and is even greater when his relatives develop prostate cancer at a young age. A variety of different genetic factors are currently being researched. Variations and mutations in certain genes may be responsible for some increases in prostate cancer rates in families. Men who carry mutations in genes known as BRCA1 or BRCA2 (these are genes implicated in breast and ovarian cancer in women) may have a 2 to 5 fold increase in prostate cancer risk. Men with high levels of testosterone or a hormone known as IGF-1 (insulin-like growth factor 1) seem to be at a higher risk for developing prostate cancer as well.
How can I prevent prostate cancer?
Because prostate cancer is a common disease and often has a very slow growing course, there is a lot of interest in trying to prevent prostate cancer with drugs, foods, or nutrients. Even a compound that could slow the progression of the disease could potentially decrease mortality from it. Right now, the best way to try and prevent prostate cancer is to modify the risk factors for prostate cancer that you have control over. You may want to try to eat a low fat diet that is rich in fruits and vegetables. Although certain foods, vitamins and minerals have been suggested to decrease your chances for getting prostate cancer, doctors still need more data before any particular food or supplement can be endorsed for preventing prostate cancer. Currently, there are studies looking at selenium, lycopen, vitamin A and other retinoids, vitamin D, vitamin E, and soy for prostate cancer prevention.

There is also interest in preventing prostate cancer by using drugs. We know that hormones like testosterone can cause prostate cancers to grow and develop, so there are experiments looking at drugs that can decrease the levels of testosterone in the prostate to attempt to stop prostate cancer from forming and growing. Drugs like Flutamide and Finasteride work in this manner, and they are currently under investigation for prostate cancer prevention. Another way to decrease testosterone in the prostate is to decrease the total amount of testosterone in the body. Drugs that decrease total body testosterone have a whole host of undesirable side effects (drugs that do this are currently used to treat men who have already developed prostate cancer and will be discussed later in the treatment section), so they aren't nearly as good choices for prostate cancer prevention.

What screening tests are available?
Whether or not men should be screened for prostate cancer is an intensely debated issue. We know that prostate cancer usually grows very slowly, so intuitively it would make sense that we could reduce mortality from prostate cancer by picking it up early so it could be treated before it spreads. However, in order for a screening test to be fully embraced, we need to prove that picking up a disease early actually does help reduce the number of deaths. Right now, there is no good data showing that screening for prostate cancer reduces deaths from prostate cancer. There are currently very large trials on-going to see which populations of men will benefit most.

Currently, there are two methods that physicians use to screen for prostate cancer. One of them is called a digital rectal exam (DRE). A digital rectal exam is done in your primary care physician's office. Because your prostate is so close to your rectum, your doctor can feel it by inserting a gloved, lubricated finger into your anus. Your doctor can feel if there are lumps, asymmetries, or if your prostate is enlarged. A digital rectal exam is uncomfortable, but not painful. It is a useful test, but it is not perfect because some small cancers can be missed and only the bottom and sides of the prostate can be examined in this manner. Although it isn't a perfect test, it becomes more useful when it is combined with another test called a PSA.

A PSA (prostate specific antigen) test is a blood test that looks for a protein that the prostate makes. Normal prostate tissue makes a little bit of PSA, but prostate cancer usually makes much more. By checking to see if your PSA is elevated, your doctor can screen you for prostate cancer. The PSA test isn't perfect either, because some tumors won't elevate the PSA and some other processes (like benign prostatic hyperplasia and prostatitis) can cause it to be falsely elevated. However, the higher your PSA is, the more likely the elevation is caused by a prostate cancer. The cut-off that your doctor usually uses is 4.0 ng/ml, meaning that anything below 4.0 ng/ml is normal and anything above it is abnormal. If your PSA is elevated, or you have an abnormal digital rectal exam, then you need to get further evaluation; however, this doesn't necessarily mean that you have prostate cancer. The only way to know for sure whether or not you have cancer is to get a sample of your prostate from a biopsy.

Both a digital rectal exam and a PSA are simple, non-invasive tests. Most physicians recommend screening for prostate cancer with these tests in men with a life expectance of 10 years or more. However, some doctors don't think screening for prostate cancer is worth doing. One of the downsides is that you may go through an extensive workup and treatment for a disease that never would have shortened your life. We know that some prostate cancers are very slow growing (often taking more than 10 years to become significant), so if your life expectancy is less than 10 years it may not be worthwhile to go through the process of screening, biopsy and treatment. The treatment options for prostate cancer are not completely benign, and all of them have the potential for side effects. However, it is difficult for physicians to determine which prostate cancers will progress versus those that will remain indolent in any individual patient. Another argument against prostate cancer screening is that it has never been proven to save lives in studies of large populations. However, many doctors think that newer treatments for early stage prostate cancers may make this argument obsolete. Data from large trials currently being carried out should help to settle this argument in the near future.

The American Cancer Society and the American Urological Society recommend regular prostate cancer screening. The American Cancer Society recommends that men start getting annual PSAs and digital rectal exams starting at age 50, unless they are high risk (meaning they have a family history of prostate cancer or are African-American), who should begin screening at age 45. However, they mention that screening should only be carried out if your life expectancy is greater than 10 years, so men in their 80s and 90s (especially if they have other serious medical problems) should probably not be screened. The most important thing is to discuss the issue with your doctor. Decisions about screening should be individualized and reached after hearing about the potential benefits and harms of screening, biopsy and treatment.

What are the signs of prostate cancer?
Most early prostate cancers are detected with PSA tests or digital rectal exams before they cause any symptoms. However, more advanced prostate cancers can cause a variety of symptoms including:

  • trouble starting urination
  • urinating much more frequently than usual
  • the feeling that you can't release all of your urine
  • pain on urination or ejaculation
  • blood in your urine or semen
  • impotence
  • bone pain
All of these symptoms can be caused by a variety of things besides prostate cancer, so experiencing them doesn't necessarily mean you have prostate cancer. When older men have problems urinating, it is usually caused by process called benign prostatic hyperplasia (BPH) which is not prostate cancer. If you experience any of these symptoms, you need to see your doctor for evaluation.

  1. Stage I - tumor cannot be felt during a digital rectal exam; it was detected by an elevated PSA blood test or incidentally found during another prostate procedure for a benign condition.
  2. Stage II - tumor can be felt during a digital rectal exam, but it has not spread beyond the prostate and it hasn't spread to lymph nodes or other organs
  3. Stage III - tumor extends outside the prostate and can be in the seminal vesicles, but not in any other organs or lymph nodes
  4. Stage IV - tumor has spread to other organs or lymph nodes

There are many different ways to treat prostate cancer, and you will most likely be consulting multiple types of doctors before making a final decision. Physicians are not always in agreement as to the way to proceed because there haven't been enough large trials that compare the different treatment modalities. For prostate cancer, it is important that you get a second opinion and you should talk to both urologists and radiation oncologists to hear about the benefits and risks of surgery, hormonal therapy and radiation in your particular case. If your prostate cancer has already spread at the time of diagnosis, you will also need a medical oncologist to talk about chemotherapy. The most important thing is to discuss your options and make a decision that suits your lifestyle, beliefs and values.
Surgery is a common form of treatment for men with prostate cancer. Surgery attempts to cure prostate cancer by removing the entire prostate and getting all of the cancer out of the body. An attempt at a surgical cure for prostate cancer is usually done with early stage prostate cancers, but sometimes surgery will be used to relieve symptoms in advanced stage prostate cancers. Surgery for prostate cancer is generally felt to be equivalent to radiation for prostate cancer in terms of survival, especially in early stage, low to intermediate grade cancers. The decision to have surgery versus radiation is often made on the basis of the patient's age and health status; the two different approaches have different side effect profiles depending on the patient's age.
The most common surgical procedure for prostate cancer is known as a radical prostatectomy. Radical prostatectomy means that the entire prostate gland is removed from around the tube that connects the bladder to the penis (the urethra). This surgery can be done in two different ways, the retropubic approach and the perineal approach. The retropubic approach means that incision in made in the lower abdomen, while the perineal approach means that the incision is made between the scrotum and the anus. Often times during a retropubic approach, the surgeon will remove some lymph nodes in the area and have them quickly examined by a pathologist for signs of cancer. If the nodes have cancer, then the surgeon will not to proceed with the operation. This is the major reason a retropubic approach is used in most surgeries today.
Radical prostatectomies are very safe surgeries with few life threatening complications; however, there is a significant risk for other side effects. Both urinary incontinence (not being able to hold in your urine) and impotence (inability to achieve and maintain an erection) are commonly associated with this procedure. The risk for having either of these side effects increases with age; this is why younger men are often recommended to have surgery while older men are recommended to have radiation. The skill of your particular surgeon influences your chances of having these side effects during a radical prostatectomy. Talk to your surgeon about their complication rates before your operation. Sometimes, particularly with lower grade and smaller cancers, a nerve sparing prostatectomy can be performed. This type of prostatectomy can decrease the chances that you will be impotent after the procedure. However, there is always a risk and not every patient is a candidate for a nerve sparing prostatectomy. With surgery, urinary incontinence and impotence are often most severe right after the operation and get better with time. There are things that your doctors can recommend to help you with either of these problems. Talk to your urologist about your options.

Radiotherapy
Prostate cancer commonly is treated with radiation therapy. Radiation therapy uses high energy rays (similar to x-rays) to kill cancer cells. Radiation therapy is another option besides surgery for early stage prostate cancer; and when advanced stage prostate cancer needs to be treated, it is usually done with radiation therapy. Radiation helps avoid surgery in patients who are too ill to risk having anaesthesia. Radiation is usually offered to older patients in the case of early stage prostate cancer because of its side effect profile is less than surgery in the elderly. Radiation can have impotence rates similar to surgery, but the risk of urinary incontinence is very low. Impotence develops months to years after the radiation treatment, unlike with surgery, which tends to have the side effects occur immediately. Other side effects from radiation include bladder irritation, which can cause urinary frequency and urgency as well as bladder pain, and diarrhea or rectal bleeding. Your radiation oncologist tries to limit the amount of radiation to other organs, but often the bladder and rectum can get some dosage because they are in such close proximity to the prostate.

Radiation therapy for prostate cancer either comes from an external source (external beam radiation) or an internal source where small radioactive seeds are implanted into the patient's prostate (brachytherapy). External beam radiation therapy requires patients to come in 5 days a week for up 6-8 weeks to a radiation therapy treatment center. The treatment takes just a few minutes, and it is painless. Brachytherapy is done as a one-time insertion, in the operating room. Brachytherapy cannot be done in all patients and is usually reserved for early stage prostate cancers. Your radiation oncologist can answer questions about the utility, process, and side effects of both of these types of radiation therapy in your particular case.
Hormonal Therapy
Both normal prostate tissue and prostate cancers depend on male sex hormones, called androgens, to grow and replicate. Testosterone is an androgen very important to the prostate gland. Men make androgens in their testicles. One of the ways to treat prostate cancer is to remove androgens from the body, thus making the cancer shrink and then grow more slowly. There are a few different ways to remove androgens: you can remove a man's testicles (called an orchiectomy), you can give a man drugs that block the production of androgens (called LHRH agonists), you can give a man drugs that block androgen receptors (called anti-androgens) or you can give a man estrogens. Different methods of deceasing androgens are often used in the same patient: using LHRH agonists with anti-androgens can achieve what is known as a total androgen blockade. Hormone therapy can also be used in conjunction with other treatments, especially in the case of advanced stage prostate cancer being treated with radiation therapy. In that case, hormonal therapy is often given before the radiation and this is known as neoadjuvant hormonal therapy. Another use for hormones is in patients who present with metastatic disease. After a while, all prostate cancers will become resistant to hormonal therapy. However, this often takes many years and hormonal therapy can buy a lot of time in patients with extensive disease or patients who choose not to undergo surgery or radiation.

There are a number of side effects associated with hormonal therapy. Hormonal therapy will almost universally cause impotence and the loss of your sex drive. It can also cause breast enlargement, hot flashes, and muscle and bone loss (osteoporosis). There are some things your doctors can prescribe to help with bone loss and hot flashes, but little can be done about loss of libido and impotence.

Chemotherapy
Chemotherapy is the use of anti-cancer drugs that go throughout the entire body. Chemotherapy is prescribed by medical oncologists, who are experts at choosing appropriate regimens for particular patients. Chemotherapy for prostate cancer is generally only reserved for very advanced cancers that are no longer responsive to hormonal therapy. There are a number of chemotherapy drugs that can be used for prostate cancer, and they are often used in combinations. A common chemotherapy regimen is Mitoxantrone with Coritcosteroids; and other regimens that are becoming increasingly popular use a drug called Estramustane with drugs called Taxanes. The use of chemotherapy in prostate cancer is currently being studied and men who get chemotherapy are encouraged to talk to their doctors about experimental trials. There are advantages and disadvantages to each of the different regimens that your medical oncologist will discuss with you. Based on your own health, your personal values and wishes, and side effects you may wish to avoid, you can work with your doctors to come up with the best regimen for your lifestyle

Cryosurgery
Cryosurgery is a somewhat experimental approach to treating prostate cancer whereby probes with liquid nitrogen are implanted into the prostate and then the tissue is frozen. This freezing kills the cancer cells, and it can be repeated multiple times if needed. However, data to date has shown that cryosurgery is not as effective as radiation and surgery for treating prostate cancer. Cryosurgery also has a variety of side effects including urinary incontinence and impotence.

Watchful Waiting
Some patients choose to receive no therapy for their prostate cancer in the hopes that it will grow very slowly. By avoiding any therapy, they avoid the side effects that come along with surgery, radiation, or hormones. Watchful waiting is appropriate for older men with small, low-grade tumors, and slowly rising PSAs, and multiple other medical problems. Watchful waiting can be considered in patients who have a life expectancy less than 10 years as long as the cancer isn't large or of a high grade. Men who choose to undergo watchful waiting should have PSAs and digital rectal exams done every 3-6 months, and need to be re-biopsied at some point to make sure the grade hasn't become less favorable. However, it is never really clear what change in clinical status should institute treatment. Also, if the tumor has progressed, they may no longer be eligible for curative therapy.

Follow-up testing
>Once a patient has been treated for prostate cancer, they need to be closely followed for a recurrence. At first, you will have follow-up visits fairly often. The longer you are free of disease, the less often you will have to go for checkups. Your doctor will tell you when he or she wants follow-up visits, PSAs and x-rays or scans depending on your case. Your doctor will also probably do digital rectal exams regularly during your office visits. It is very important that you let your doctor know about any symptoms you are experiencing and that you keep all of your follow-up appointments.

Clinical trials are extremely important in furthering our knowledge of this disease. It is through clinical trials that we know what we do today, and many exciting new therapies are currently being tested. Talk to your doctor about participating in clinical trials in your area.

This article is meant to give you a better understanding of prostate cancer. Use this knowledge when meeting with your physician, making treatment decisions, and continuing your search for information. You can learn more about prostate cancer on OncoLink through the related links to the left., for complete information visit to Link Here

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