Prostate Cancer

Introduction

One in six men will develop prostate cancer in his lifetime, so it is a rare individual who does not have a father, brother, grandfather, uncle, or friend with this disease. As the baby-boom generation celebrates its 60th and subsequent birthdays, the number of new cases of prostate cancer is expected to rise dramatically. However, knowledge is power. The more you know about who is at risk, the warning signs, and how this disease is treated; the better equipped you will be to fight it. The good news is that there is a very simple test to screen for prostate cancer. Read on to learn more about this common type of cancer.

What is it?

The prostate is a walnut-sized gland found only in men. It is located just below the bladder and in front of the rectum where it can be felt during a rectal examination. The prostate gland produces some of the fluid that carries sperm. The urethra, the tube that carries urine and semen out of the body through the penis, runs through the prostate. The prostate gland may be a source of many health problems for men, including prostate cancer. Prostate cancer is often devastating to men, not only because of the effect on their health, but also because the treatments can result in sexual dysfunction and bladder control problems.

For American men, prostate cancer is the most common cancer and the second-leading cause of cancer death. The National Cancer Institute states that there have been nearly 220,000 new cases of prostate cancer reported as of November 2007, and 27,050 men have died. One out of every six men will be diagnosed with prostate cancer sometime during his life, and one of every 34 men with the disease will die as a result of the spread of prostate cancer cells to other parts of the body.

One test doctors can perform to help determine if an individual is at risk for prostate cancer is a prostate specific antigen (PSA) test. PSA is a protein made by the prostate that is elevated in patients with prostate diseases. The PSA test is regarded as superior to a rectal examination because early-stage prostate cancer (see the classification system discussed below) cannot be detected by a rectal exam.

An elevated PSA can indicate a small, early-stage prostate cancer, but it can also indicate the presence of benign prostatic hyperplasia (BPH)?an unharmful condition where the prostate is enlarged. Therefore, it is important to understand that an elevated PSA does not necessarily indicate cancer. Despite this, the PSA test is a very important, highly recommended screening. The American Cancer Society recommends an annual PSA test for all men beginning at age 50 and for younger men who are at high risk for prostate cancer (see "What are the Risk Factors?").

If a test indicates an elevated PSA or a doctor has other reasons to suspect prostate cancer, a prostate ultrasound may be conducted. In this procedure, a probe is placed in the rectum and sound waves are emitted. The sound waves are converted into pictures that allow doctors to determine if cancer or enlargements of the prostate are present. If a possible cancer is seen on the ultrasound, an ultrasound-guided biopsy may be performed. In this procedure, ultrasound is used to guide a needle into the prostate to remove a sample of tissue, which is then examined under a microscope to determine if cancerous cells are present.

The American Urologic System classifies prostate cancer into the following progressive stages:

  • Stage A or Stage I (earliest stage): The cancer cannot be felt during a rectal exam. The cancer cells are contained within the prostate and have not spread to surrounding lymph nodes.

  • Stage B or Stage II: The cancer cells are still contained within the prostate and have not spread to surrounding lymph nodes. The cancer can be felt during a rectal exam or found when a biopsy is performed.

  • Stage C or Stage III: The cancer has spread to nearby tissues.

  • Stage D or Stage IV (most serious stage): The cancer has spread to lymph nodes or to other parts of the body (known as "metastasis").

Prostate cancer can also be classified by the Gleason grading system, by which a number of 1 to 10 is assigned based on how closely the arrangement of cells in the cancerous tissue resembles normal prostate tissue. If the cancerous tissue resembles normal prostate tissue, a grade of 1 is assigned. Grades 2 to 4 indicate intermediate features, meaning the cancer has not spread throughout the prostate. If the cancer appears to be spread haphazardly throughout the prostate, a grade of 5 or 6 is assigned. Grades from 7 to 10 are considered severe and indicate a poorer prognosis.

What causes it?

The exact cause of prostate cancer has not been determined. Genetics may be a key factor since prostate cancer can run in families. Other risk factors for developing this cancer have been identified. See "What are the Risk Factors?"

Who has it?

Prostate cancer can strike men of all ages but is rarely diagnosed in men younger than age 40. The average age of American men with this disease is 72 to 74. In the United States, the disease is most prevalent among African-American men. Throughout the world, the highest rates of prostate cancer are found in the United States and Western Europe.

In 2005, over 232,000 American men were diagnosed with prostate cancer. Of these cases, more than 30,000 were severe enough to be considered fatal. The Prostate Cancer Foundation has estimated that by 2015, there will be more than 300,000 new prostate cancer cases each year. This is primarily because of the aging baby-boomer population.

What are the risk factors?

Researchers are aware of several risk factors for prostate cancer but are still unsure of why one man develops the disease and another does not. Research suggests that high levels of testosterone may increase a man's risk for the disease. A family history of prostate cancer is associated with a twofold to threefold risk of developing the disease. It is suspected that a high-fat diet may also increase the risk of developing of prostate cancer. Additional risk factors that have a potential relationship to the development of prostate cancer are being older than 50 and being African American.

What are the symptoms?

Because prostate cancer is a slowly developing cancer, it typically does not cause symptoms for many years. By the time symptoms occur, however, the disease generally has spread beyond the prostate gland. Because of this, regular PSA screenings are critical in catching the disease at the earliest, most treatable stages.

Symptoms may include the following:

  • Urinary frequency, especially at night
  • Difficulty starting urination or holding urine
  • Inability to completely empty the bladder
  • Weak or interrupted flow of urine
  • Painful or burning sensation during urination
  • Impotence or less-firm penile erections
  • Blood in the urine or semen
  • Frequent pain or stiffness in the lower back, hips, or upper thighs
  • Weight loss

It is important to keep in mind that these symptoms are not always specific to prostate cancer. They may be due instead to noncancerous conditions such as benign prostatic hypertrophy or urinary tract infections. What is important is that you contact your doctor if you experience any of these symptoms.

How is it treated?

The rate of survival for men with prostate cancer is increasing. Approximately 97% of men diagnosed with this disease survive at least 5 years, 79% survive at least 10 years, and 57% survive at least 15 years. This is because several effective treatment options are now available. It is important to understand the available options and work with a healthcare provider to determine the best treatment plan for you.

Two factors should be considered in deciding on a particular treatment for prostate cancer:

  • Stage of the disease: If the prostate cancer is in Stage A or Stage B, careful observation, surgery, or radiation are all options for treatment. If the cancer has spread to areas other than the prostate (Stage C or Stage D), hormonal therapy may be needed to improve symptoms and delay further progression.

  • Age and general health: Men in their fifties or sixties may be more interested in treatment that offers the best chance for a cure, such as radiation therapy or surgery. Older men in their seventies or eighties may prefer less invasive treatment only to reduce symptoms, such as hormonal therapy or careful observation.

    The following are the accepted treatments for prostate cancer:

    Careful Observation

    Because prostate cancer is typically a slowly developing cancer, careful observation (also known as "watchful waiting") may be an option. This is especially true for patients who are in the early stages of the disease, those older than 65 who have other serious medical problems, or men with a shortened life expectancy due to other medical conditions. In such cases, careful observation allows the patient to avoid the potential side effects associated with more aggressive therapies.

    Surgery

    There are several types of prostate surgeries, primarily used to treat the disease in younger men:

    • Radical retropubic prostatectomy is the removal of the entire prostate gland and nearby lymph nodes through an incision made in the abdomen.

    • Radical perineal prostatectomy is the removal of the entire prostate gland through an incision made between the scrotum and the anus.

    • Transurethral resection of the prostate (TURP) is the removal of part of the prostate gland with an instrument that is inserted through the urethra. This method is used to remove tissue that blocks urine flow.

    • Orchiectomy is a surgery used to completely remove the testicles so that cancer cells are deprived of the male hormone (testosterone) they need to grow.

    As with any surgery, there are always risks, such as infection and bleeding. Another consideration is recovery time. A patient may be somewhat uncomfortable and weak while recovering from surgery. Long-term problems that can be associated with prostate surgery include rectal injury, inability to control urination, permanent impotence, and the inability to produce sperm. Sexual dysfunction was a common side effect of surgery in previous years; however, recent surgical procedures have been developed that protect sexual nerves and allow the patient to function normally. Before surgery is selected as a treatment option, the risks versus benefits should be discussed in detail with a doctor.

    Radiation

    The purpose of radiation therapy is to kill cancer cells with high-energy X-rays. Radiation therapy is an alternative to surgery in patients with the early stages of prostate cancer. It is also sometimes used after surgery to destroy any remaining cancer cells. Radiation therapy can cause side effects such as fatigue, hair loss, or irritation of the skin in treated areas. Most radiation techniques minimize the amount of radiation that reaches healthy areas of the body.

    A relatively new type of radiation is known as radioactive seed implant therapy, or brachytherapy. Small radioactive seeds are placed in the prostate and deliver their radiation from inside the body. This is exciting because in external techniques, radiation must penetrate healthy tissue before reaching the prostate. In this variation, the radiation reaches the prostate first.

    Hormonal Therapy

    Hormonal therapy has two general purposes: to treat cancer that has spread and to prevent cancer from returning after surgery or radiation treatment. Because higher levels of testosterone can contribute to the growth of prostate cancer cells, hormonal therapy is used to decrease or eliminate testosterone production.

    The types of hormonal treatment that are available include the following:

    • Gonadotropin-Releasing Hormone Analogs (GnRHa), such as leuprolide and goserelin, work by decreasing the amount of testosterone that is produced. Side effects from these drugs include hot flashes, stomach upset, breast tenderness, impotence, and loss of sexual desire.

    • Antiandrogens such as flutamide, bicalutamide, and nilutamide are used to block the action of hormones known as androgens (also known as steroid hormones). For example, testosterone stimulates the development of male characteristics such as muscle development and deepening of the voice. Antiandrogens decrease the prostate size resulting in improvement in symptoms such as urinary frequency, pain when urinating, and stiffness or pain in the lower back, hips, or upper thighs. Side effects can include nausea, vomiting, diarrhea, breast growth or tenderness, stomach upset, and hot flashes.

    You can learn more about these drugs by clicking on the Drug Class links on the previous page.

    Combination Therapy

    Combination therapy (or total androgen blockade) aims at more completely eliminating the effects of male hormones by using an antiandrogen drug following surgery or treatment with an Gonadotropin-Releasing Hormone Analog (GnRHa). Both surgery (particularly orchiectomy, removal of the testes) and treatment with a Gonadotropin-Releasing Hormone Analog (GnRHa) halt the production of testosterone from the testicles. However, the adrenal glands still produce a small amount of male hormones that can be blocked effectively by an antiandrogen, thus providing greater protection against prostate cancer. Men who receive combination therapy may experience more side effects than those who receive a single method of hormonal therapy.

    Helping Yourself

    A diagnosis of prostate cancer can affect many aspects of your life, but there are several things you can do to increase your quality of life and slow the progression of the disease:

    • Rely on a strong support network. Family, friends, and support groups can help you cope better with the disease.

    • Don't smoke tobacco products or use illegal drugs. Smoking and using illegal drugs can further weaken your body and increase its susceptibility to invading cancer cells.

    • Eat healthy foods. Be sure to include fruits, vegetables, and calcium-rich foods in your diet.

    • Exercise regularly. Exercise will increase your strength and energy levels. Always make sure to consult your doctor before beginning an exercise regimen.

    • Follow your doctor's instructions. Keep all of your appointments and take your medications exactly as directed. Don't stop taking your medication or change the dosage you take without consulting your doctor.

    If you have not been diagnosed with prostate cancer but have been told you are at high risk for the disease, dietary changes and micronutrients may have a preventive effect. For example, consumption of soy and tomato-based products has been shown to be associated with a decrease in the risk of prostate cancer. Micronutrients such as selenium and vitamin E may help decrease the risk of prostate cancer by enhancing the immune system and decreasing the production of testosterone.

    What is on the horizon?

    New and more effective treatments and prevention therapies for prostate cancer are constantly being researched. Two drugs that reduce the size of the prostate and are currently used to treat BPH have been studied as potential prevention therapies for prostate cancer. Results of the Prostate Cancer Prevention Trial, which studied the use of finasteride (brand name: Proscar), were recently reported. At the end of the study, the men taking finasteride were about 25% less likely to have developed prostate cancer than those getting a placebo. But the cancers that did develop in the men taking finasteride were more aggressive, meaning that they were more likely to grow and spread. Because of this study, it is not clear whether finasteride should be used at this time to prevent prostate cancer. Although this study did not show a clear-cut benefit for finasteride, a study is still being conducted to test whether another drug, dutasteride, might be helpful in preventing prostate cancer.

    Other medications being studied include NSAIDS, biologic therapies, angiogenesis inhibitors, and chemotherapy medications. Nonsteroidal anti-inflammatory (NSAID) medications such as naproxen and ibuprofen inhibit an enzyme present in cancer cells of the prostate, but whether they truly have benefit in prostate cancer prevention is unclear at this time. Biologic therapy is also known as immunotherapy or biotherapy. In this treatment, the patient?s immune system is stimulated and becomes better able to fight the cancer. Angiogenesis inhibitors such as bevacizumab (Avastin) are also being tested in prostate cancer. Angiogenesis refers to the process where new blood vessels are formed that supply the cancer with blood flow and nutrients. If this process can be stopped, the tumor would die. A drug called thalidomide is also being researched for its similar effects. Chemotherapy is commonly used in other types of cancers, and current clinical trials are studying the effects of various chemotherapy medications and chemotherapy combinations on prostate cancer. Chemotherapy medications are taken by mouth or injected into the blood where the medication travels to the cancer and destroys it.

    In addition to the testing of new medications, new radiation and surgical therapies are also being examined. Some areas of the United States have clinics that use proton beam therapy to treat prostate cancer. In this procedure, protons instead of x-rays are used to kill cancer cells. The effectiveness of this treatment compared to x-ray radiation is currently unclear. Another new surgical procedure is known as cryotherapy. Cryotherapy is a procedure that uses an instrument called a cryoprobe to freeze and destroy the tumor. The treatment is currently considered experimental due to variations in response to the procedure and a lack of long-term research. If effective, the treatment would be a good alternative for patients who do relapse after receiving radiation. Another treatment being studied includes high-intensity focus ultrasound. In this technique, a probe is inserted into the rectum and produces intense sound waves that kill the cancer.

    Clinical trials now under way aim at improving the comfort and quality of life of prostate cancer patients. Investigations are also in progress to determine whether a diet low in fat and high in soy, fruits, and vegetables is effective in preventing the recurrence of prostate cancer.

    References

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    Demarzo AM, Nelson WG, Isaacs WB, et al. Pathological and molecular aspects of prostate cancer. The Lancet. 2003;361:955-64.

    Gronberg H. Prostate cancer epidemiology. The Lancet. 2003;361:859-64.

    Jemal, A et al. Cancer Statistics, 2005. CA: Cancer J Clin. 2005; 55: 10-30.

    Kolesar JM. Prostate Cancer. In: Dipiro JT, Talbert RL, Yee GC, et al. (eds.). Pharmacotherapy: a pathophysiologic approach. 6th ed. New York: McGraw-Hill; 2005:2421-37.

    Mayo Clinic. Disease and Conditions. Available at: http://www.mayoclinic.com/health/prostate-cancer/DS00043. Accessed November 2007.

    National Cancer Institute Website. Available at: http://www.nci.nih.gov. Accessed November 2007.

    Nelson WG, Demarzo AM, Isaacs WB. Mechanisms of disease: prostate cancer. New England Journal of Medicine. 2003; 349:366-81.

    Prostate Cancer Foundation Website. Available at: http://www.prostatecancerfoundation.org. Accessed November 2007.

    RadiologyInfo. American College of Radiology and the Radiological Society of North America. Available at: http://www.radiologyinfo.org. Accessed November 2007.

    Prostate Cancer Health Condition Last Updated: December 2007

    Note: The above information is intended to supplement, not substitute for, the expertise and judgment of your physician, pharmacist, or other healthcare professional. It is not intended to diagnose a health condition, but it can be used as a guide to help you decide if you should seek professional treatment or to help you learn more about your condition once it has been diagnosed.

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