Prostate cancer is the most common type of cancer in men in the United States. Of all the men who are diagnosed with cancer each year, more than one-fourth have prostate cancer.
Diagram of the prostate and nearby organs
The prostate is a gland in a man's reproductive system. It makes and stores seminal fluid, a milky fluid that nourishes sperm. This fluid is released to form part of semen.
The prostate is about the size of a walnut. It is located below the urinary bladder and in front of the rectum. It surrounds the upper part of the urethra, the tube that empties urine from the bladder. If the prostate grows too large, the flow of urine can be slowed or stopped.
To work properly, the prostate needs male hormones (androgens). Male hormones are responsible for male sex characteristics. The main male hormone is testosterone, which is made mainly by the testicles. Some male hormones are produced in small amounts by the adrenal glands.
Understanding the cancer process
Cancer is a group of many related diseases. These diseases begin in cells, the body's basic unit of life. Cells have many important functions throughout the body.
Normally, cells grow and divide to form new cells in an orderly way. They perform their functions for a while, and then they die. This process helps keep the body healthy.
Sometimes, however, cells do not die. Instead, they keep dividing and creating new cells that the body does not need. They form a mass of tissue, called a growth or tumor.
Tumors can be benign or malignant:
- Benign tumors are not cancer. They can usually be removed, and in most cases, they do not come back. Cells from benign tumors do not spread to other parts of the body. Most important, benign tumors of the prostate are not a threat to life. Benign prostatic hyperplasia (BPH) is the abnormal growth of benign prostate cells. In BPH, the prostate grows larger and presses against the urethra and bladder, interfering with the normal flow of urine. More than half of the men in the United States between the ages of 60 and 70 and as many as 90 percent between the ages of 70 and 90 have symptoms of BPH. For some men, the symptoms may be severe enough to require treatment.
- Malignant tumors are cancer. Cells in these tumors are abnormal. They divide without control or order, and they do not die. They can invade and damage nearby tissues and organs. Also, cancer cells can break away from a malignant tumor and enter the bloodstream and lymphatic system. This is how cancer spreads from the original (primary) cancer site to form new (secondary) tumors in other organs. The spread of cancer is called metastasis.
When prostate cancer spreads (metastasizes) outside the prostate, cancer cells are often found in nearby lymph nodes. If the cancer has reached these nodes, it means that cancer cells may have spread to other parts of the body -- other lymph nodes and other organs, such as the bones, bladder, or rectum. When cancer spreads from its original location to another part of the body, the new tumor has the same kind of abnormal cells and the same name as the primary tumor. For example, if prostate cancer spreads to the bones, the cancer cells in the new tumor are prostate cancer cells. The disease is metastatic prostate cancer; it is not bone cancer.
Prostate cancer: who's at risk
The causes of prostate cancer are not well understood. Doctors cannot explain why one man gets prostate cancer and another does not.
Researchers are studying factors that may increase the risk of this disease. Studies have found that the following risk factors are associated with prostate cancer:
- Age. In the United States, prostate cancer is found mainly in men over age 55. The average age of patients at the time of diagnosis is 70.
- Family history of prostate cancer. A man's risk for developing prostate cancer is higher if his father or brother has had the disease.
- Race. This disease is much more common in African American men than in white men. It is less common in Asian and American Indian men.
- Diet and dietary factors. Some evidence suggests that a diet high in animal fat may increase the risk of prostate cancer and a diet high in fruits and vegetables may decrease the risk. Studies are in progress to learn whether men can reduce their risk of prostate cancer by taking certain dietary supplements.
Although a few studies suggested that having a vasectomy might increase a man's risk for prostate cancer, most studies do not support this finding. Scientists have studied whether benign prostatic hyperplasia, obesity, lack of exercise, smoking, radiation exposure, or a sexually transmitted virus might increase the risk for prostate cancer. At this time, there is little evidence that these factors contribute to an increased risk.
In a study published in 1987 Ross et al found that circumcision was negatively associated with prostate cancer risk among blacks and whites in southern California (RR = 0.5 in whites; RR = 0.6 in blacks).
There is a lower occurrence of prostate cancer in men in less developed countries. It is speculated that the developed countries have higher levels of carcinogens in the environment that lead to the development of prostate cancer; men who move from less developed countries to more developed ones have an increased occurrence of prostate cancer.
Detecting prostate cancer
Early and accurate detection of prostate cancer offer the best hope of cure for the disease. The American Cancer Society and American Urological Association recommend annual examinations for prostate cancer for men at risk (all men over 50; or men over 40 with family history of prostate cancer; or African-American men). This is currently done by two procedures:
Digital rectal examination (DRE) -- During this procedure, the physician inserts a gloved, lubricated finger into the rectum in order to feel the size and shape of the prostate to find areas that are for hard or lumpy, which may indicate cancer.
- Blood test for prostate-specific antigen (PSA) -- a lab measures the levels of PSA in a blood sample. Levels lower than 4 ng/mL (nanograms per milliliter) are considered normal. Levels greater than 10 ng/mL are considered abnormal. PSA levels between 4 and 10 ng/mL are considered to be borderline.
The level of PSA may rise in men who have prostate cancer, benign prostate hyperplasia (BPH), or infection in the prostate (prostatitis). Also, some medications and herbal preparations can cause an inaccurate reading of blood PSA levels. Some helpful hints for obtaining a maximally accurate PSA test include: (1) Don’t ejaculate for 2 days prior to having a PSA test as this can raise PSA levels, and (2) tell your doctor if you are taking Proscar, Avodart or Propecia. These drugs, used to treat BPH and baldness, will likely lower your PSA levels. Also, (3) be sure that the DRE is performed after drawing blood for the PSA test, as the DRE can artificially raise PSA levels. Herbal supplements can also affect PSA levels. Be sure to tell your physician about any supplements that you are taking before the PSA test.
Abnormal DRE or high serum PSA levels are reasons for a medical follow up. The doctor will take the results into account in deciding whether to check the patient further for signs of cancer. The doctor can explain more about each test.
When the total PSA blood test is in the grey zone (between 4 and 10 ng/mL) and the DRE is normal, the percentage of free PSA (unbound to other proteins) in the blood is used to distinguish between BPH and prostate cancer. A low value for percent-free PSA indicates a higher probability of prostate cancer.
Currently, a biopsy is the only procedure that can definitively diagnose prostate cancer. It is performed when digital rectal examination shows abnormalities or a patient has high total PSA in the serum. The biopsy gun inserts and removes the needles (usually three to six for each side of the prostate) in less than a second. The tissue samples are then studied under a microscope to determine if cancer cells are present and to evaluate the extent of the cancer.
Early prostate cancer often does not cause symptoms. But prostate cancer can cause any of these problems:
- A need to urinate frequently, especially at night;
- Difficulty starting urination or holding back urine;
- Inability to urinate;
- Weak or interrupted flow of urine;
- Painful or burning urination;
- Difficulty in having an erection;
- Painful ejaculation;
- Blood in urine or semen; or
- Frequent pain or stiffness in the lower back, hips, or upper thighs.
Any of these symptoms may be caused by cancer or by other, less serious health problems, such as BPH or an infection. A man who has symptoms like these should see his doctor or a urologist (a doctor who specializes in treating diseases of the genitourinary system).
Diagnosing prostate cancer
If a man has symptoms or test results that suggest prostate cancer, his doctor asks about his personal and family medical history, performs a physical exam, and may order laboratory tests. The exams and tests may include a digital rectal exam, a urine test to check for blood or infection, and a blood test to measure PSA. In some cases, the doctor also may check the level of prostatic acid phosphatase (PAP) in the blood, especially if the results of the PSA indicate there might be a problem.
The doctor may order exams to learn more about the cause of the symptoms. These may include:
- Transrectal ultrasonography -- sound waves that cannot be heard by humans (ultrasound) are sent out by a probe inserted into the rectum. The waves bounce off the prostate, and a computer uses the echoes to create a picture called a sonogram.
Intravenous pyelogram -- a series of x-rays of the organs of the urinary tract.
Cystoscopy -- a procedure in which a doctor looks into the urethra and bladder through a thin, lighted tube.
If test results suggest that cancer may be present, the man will need to have a biopsy. During a biopsy, the doctor removes tissue samples from the prostate, usually with a needle. A pathologist looks at the tissue under a microscope to check for cancer cells. If cancer is present, the pathologist usually reports the grade of the tumor. The grade tells how much the tumor tissue differs from normal prostate tissue and suggests how fast the tumor is likely to grow. One way of grading prostate cancer, called the Gleason system, uses scores of 2 to 10. Another system uses G1 through G4. Tumors with higher scores or grades are more likely to grow and spread than tumors with lower scores.
If the physical exam and test results do not suggest cancer, the doctor may recommend medicine to reduce the symptoms caused by an enlarged prostate. Surgery is another way to relieve these symptoms. The surgery most often used in such cases is called transurethral resection of the prostate (TURP or TUR). In TURP, an instrument is inserted through the urethra to remove prostate tissue that is pressing against the upper part of the urethra and restricting the flow of urine. (Patients may want to ask whether other procedures might be appropriate.)
Stages of prostate cancer
If cancer is found in the prostate, the doctor needs to know the stage, or extent, of the disease. Staging is a careful attempt to find out whether the cancer has spread and, if so, what parts of the body are affected. The doctor may use various blood and imaging tests to learn the stage of the disease. Treatment decisions depend on these findings.
Prostate cancer staging is a complex process. The doctor may describe the stage using a Roman number (I-IV) or a capital letter (A-D). These are the main features of each stage:
- Stage I or Stage A -- The cancer cannot be felt during a rectal exam. It may be found by accident when surgery is done for another reason, usually for BPH. There is no evidence that the cancer has spread outside the prostate.
- Stage II or Stage B -- The tumor involves more tissue within the prostate, it can be felt during a rectal exam, or it is found with a biopsy that is done because of a high PSA level. There is no evidence that the cancer has spread outside the prostate.
- Stage III or Stage C -- The cancer has spread outside the prostate to nearby tissues.
- Stage IV or Stage D -- The cancer has spread to lymph nodes or to other parts of the body.
The most common method of staging used recently is the TNM staging system.
- TX: Primary tumor cannot be assessed
- T0: No evidence of primary tumor
- T1: Clinically inapparent tumor not palpable nor visible by imaging
- T1a: Tumor incidental histologic finding in 5% or less of tissue resected (in prostatectomy)
- T1b: Tumor incidental histologic finding in more than 5% of tissue resected
- T1c: Tumor identified by needle biopsy (e.g., because of elevated PSA)
- T2: Tumor confined within prostate
- T2a: Tumor involves one-half of 1 lobe or less
- T2b: Tumor involves more than one-half of 1 lobe but not both lobes
- T2c: Tumor involves both lobes
- T3: Tumor extends through the prostate capsule
- T3a: Extracapsular extension (unilateral or bilateral)
- T3b: Tumor invades seminal vesicle(s)
- T4: Tumor is fixed or invades adjacent structures other than seminal vesicles: bladder neck, external sphincter, rectum, levator muscles,and/or pelvic wall
- NX: Regional lymph nodes were not assessed
- N0: No regional lymph node metastasis (lymph nodes confined to the true pelvis)
- N1: Metastasis in regional lymph node(s)
- MX: Distant metastasis cannot be assessed (not evaluated by any modality)
- M0: No distant metastasis
- M1: Distant metastasis
- M1a: Nonregional lymph node(s)
- M1b: Bone(s)
- M1c: Other site(s) with or without bone disease
Treatment for prostate cancer
Getting a second opinion
Decisions about prostate cancer treatment involve many factors. Before making a decision, a man may want to get a second opinion by asking another doctor to review the diagnosis and treatment options. A short delay will not reduce the chance that treatment will be successful. Some health insurance companies require a second opinion; many others will cover a second opinion if the patient requests it. There are a number of ways to find a doctor who can give a second opinion:
- The patient's doctor may be able to recommend a specialist or team of specialists to consult. Doctors who treat prostate cancer are urologists, radiation oncologists, and medical oncologists. Patients may find it helpful to talk to a specialist in each of these areas. Different types of specialists may have different thoughts about how best to manage prostate cancer.
- In the USA, the Cancer Information Service, at 1-800-4-CANCER, can tell callers about treatment facilities, including cancer centers and other programs supported by the National Cancer Institute.
- People can get the names of doctors from their local medical society, a nearby hospital, or a medical school.
- The Official Directory of the American Board of Medical Specialties (ABMS) lists doctors' names along with their specialty and their educational background. This resource, produced by the ABMS, is available in most public libraries. The ABMS also has an online service that lists many board-certified physicians (http://www.certifieddoctor.org).
Preparing for treatment
The doctor develops a treatment plan to fit each man's needs. Treatment for prostate cancer depends on the stage of the disease and the grade of the tumor (which indicates how abnormal the cells look, and how likely they are to grow or spread). Other important factors in planning treatment are the man's age and general health and his feelings about the treatments and their possible side effects.
Many men with prostate cancer want to learn all they can about their disease, their treatment choices, and the possible side effects of treatment, so they can take an active part in decisions about their medical care. Prostate cancer can be managed in a number of ways (with watchful waiting , surgery, radiation therapy, and hormonal therapy). If the doctor recommends watchful waiting, the man's health will be monitored closely, and he will be treated only if symptoms occur or worsen. Patients considering surgery, radiation therapy, or hormonal therapy may want to consult doctors who specialize in these types of treatment.
The patient and his doctor may want to consider both the benefits and possible side effects of each option, especially the effects on sexual activity and urinary control, and other concerns about quality of life. Men with prostate cancer may find helpful information in the sections "Methods of Treatment," "Side Effects of Treatment," and "Support for Men with Prostate Cancer." Also, the patient may want to talk with his doctor about taking part in a research study to help determine the best approach or to study new kinds of treatment. "The Promise of Prostate Cancer Research" section has more information about such studies, called clinical trials.
Methods of treatment
Treatment for prostate cancer may involve watchful waiting, surgery, radiation therapy, or hormonal therapy. Some patients receive a combination of therapies. In addition, doctors are studying other methods of treatment to find out whether they are effective against this disease. (The "Promise of Cancer Research" section has information about research studies.)
Watchful waiting may be suggested for some men who have prostate cancer that is found at an early stage and appears to be slow growing. Also, watchful waiting may be advised for older men or men with other serious medical problems. For these men, the risks and possible side effects of surgery, radiation therapy, or hormonal therapy may outweigh the possible benefits. Men with early stage prostate cancer are taking part in a study to determine when or whether treatment may be necessary and effective. (See "The Promise of Prostate Cancer Research" section for information about this study.)
Surgery is a common treatment for early stage prostate cancer. The doctor may remove all of the prostate (a type of surgery called radical prostatectomy) or only part of it. In some cases, the doctor can use a new technique known as nerve-sparing surgery. This type of surgery may save the nerves that control erection. However, men with large tumors or tumors that are very close to the nerves may not be able to have this surgery.
The doctor can describe the types of surgery and can discuss and compare their benefits and risks.
- In radical retropubic prostatectomy, the doctor removes the entire prostate and nearby lymph nodes through an incision in the abdomen.
- In radical perineal prostatectomy, the doctor removes the entire prostate through an incision between the scrotum and the anus. Nearby lymph nodes are sometimes removed through a separate incision in the abdomen.
- In transurethral resection of the prostate (TURP), the doctor removes part of the prostate with an instrument that is inserted through the urethra. The cancer is cut from the prostate by electricity passing through a small wire loop on the end of the instrument. This method is used mainly to remove tissue that blocks urine flow.
If the pathologist finds cancer cells in the lymph nodes, it is likely that the disease has spread to other parts of the body. Sometimes, the doctor removes the lymph nodes before doing a prostatectomy. If the prostate cancer has not spread to the lymph nodes, the doctor then removes the prostate. But if cancer has spread to the nodes, the doctor usually does not remove the prostate, but may suggest other treatment.
While the above was the standard of care through the 1980s and early 1990s recent Journal publications indicate that "Radical prostatectomy combined with early adjunctive hormonal therapy for patients with nodal metastasis is superior to all other forms of therapy and should be considered the standard of care. This approach provides survival rates comparable with patients with clinically organ-confined prostate cancer." Radical prostatectomy for the patient with locally advanced prostate cancer. Curr Urol Rep. 2003 Jun;4(3):196-204.
Radiation therapy (also called radiotherapy) uses high-energy x-rays to kill cancer cells. Like surgery, radiation therapy is local therapy; it can affect cancer cells only in the treated area. In early stage prostate cancer, radiation can be used instead of surgery, or it may be used after surgery to destroy any cancer cells that may remain in the area. In advanced stages, it may be given to relieve pain or other problems.
Radiation may be directed at the body by a linear accelerator, or it may come from tiny radioactive seeds placed inside or near the tumor (internal or implant radiation, or brachytherapy). Men who receive radioactive seeds alone usually have small tumors. Some men with prostate cancer receive both kinds of radiation therapy.
For external radiation therapy, patients go to the hospital or clinic, usually 5 days a week for several weeks. Patients may stay in the hospital for a short time for implant radiation.
Cryotherapy is another method of treating prostate cancer. Cryotherapy is the insertion of metal rods into the prostate and circulating liquid nitrogen through these rods. This process lowers the temperature to about minus 374° F. As the tissue freezes, the formation and expansion of ice crystals within the cancerous cells cause them to rupture and die. A catheter is placed inside the urethra and a warming solution is circulated to prevent damage to the urethra. Short term results have been good however long term results appear to suggest that it is not as effective as surgery or radiation. Additionally, impotence results from cryotherapy 90 percent of the time
Hormonal therapy keeps cancer cells from getting the male hormones they need to grow. It is called systemic therapy because it can affect cancer cells throughout the body. Systemic therapy is used to treat cancer that has spread. Sometimes this type of therapy is used to try to prevent the cancer from coming back after surgery or radiation treatment.
There are several forms of hormonal therapy:
Orchiectomy is surgery to remove the testicles, which are the main source of male hormones.
- Drugs known as luteinizing hormone-releasing hormone (LH-RH) agonists can prevent the testicles from producing testosterone. Examples are leuprolide, goserelin, and buserelin.
- Drugs known as antiandrogens can block the action of androgens. Two examples are flutamide and bicalutamide.
- Drugs that can prevent the adrenal glands from making androgens include ketoconazole and aminoglutethimide .
After orchiectomy or treatment with an LH-RH agonist, the body no longer gets testosterone from the testicles. However, the adrenal glands still produce small amounts of male hormones. Sometimes, the patient is also given an antiandrogen, which blocks the effect of any remaining male hormones. This combination of treatments is known as total androgen blockade (TAB), combined hormonal therapy (CHT), combined androgen blockade (CAB), or maximal androgen deprivation (MAD). Doctors do not know for sure whether total androgen blockade is more effective than orchiectomy or LH-RH agonist alone.
Prostate cancer that has spread to other parts of the body usually can be controlled with hormonal therapy for a period of time, often several years. Eventually, however, most prostate cancers are able to grow with very little or no male hormones. When this happens, hormonal therapy is no longer effective, and the doctor may suggest other forms of treatment that are under study.
Side effects of treatment
It is hard to limit the effects of treatment so that only cancer cells are removed or destroyed. Because healthy cells and tissues may be damaged, treatment often causes unwanted side effects. Doctors and nurses will explain the possible side effects of treatment.
The side effects of cancer treatment depend mainly on the type and extent of the treatment. Also, each patient reacts differently. The NCI provides helpful, informative booklets about cancer treatments and coping with side effects, such as Understanding Treatment Choices for Prostate Cancer: Know Your Options and Radiation Therapy and You. Patients also may want to read Eating Hints for Cancer Patients. See "National Cancer Institute Information Resources" and "Other Information Resources" for additional sources of information about side effects.
Although men who choose watchful waiting avoid the side effects of surgery and radiation, there can be some negative aspects to this choice. Watchful waiting may reduce the chance of controlling the disease before it spreads. Also, older men should keep in mind that it may be harder to manage surgery and radiation therapy as they age.
Some men may decide against watchful waiting because they feel they would be uncomfortable living with an untreated cancer, even one that appears to be growing slowly or not at all. A man who chooses watchful waiting but later becomes concerned or anxious should discuss his feelings with his doctor. A different treatment approach is nearly always available.
Patients are often uncomfortable for the first few days after surgery. Their pain usually can be controlled with medicine, and patients should discuss pain relief with the doctor or nurse. The patient will wear a catheter (a tube inserted into the urethra) to drain urine for 10 days to 3 weeks. The nurse or doctor will show the man how to care for the catheter.
It is also common for patients to feel extremely tired or weak for a while. The length of time it takes to recover from an operation varies. Surgery to remove the prostate can cause long-term problems, including impotence and/or fecal or urinary incontinence. Nerve-sparing surgery is an attempt to avoid the problem of impotence. When the doctor can use nerve-sparing surgery and the operation is fully successful, impotence may be only temporary or partial. Still, some men who have this procedure may be permanently impotent.
Men who have a prostatectomy no longer produce semen, so they have dry orgasms. Men who wish to father children may consider sperm banking or a sperm retrieval procedure.
Radiation therapy may cause patients to become extremely tired, especially in the later weeks of treatment. Resting is important, but doctors usually encourage men to try to stay as active as they can. Some men may have diarrhea or frequent and uncomfortable urination.
When men with prostate cancer receive external radiation therapy, it is uncommon for the skin in the treated area to become red, dry, or tender, however there may be hair loss in the treated area. The loss is usually temporary.
Both types of radiation therapy may cause impotence in some men. While internal radiation therapy may cause temporary urinary incontinence, external radiation therapy causes temporary bowel inflammation. Long-term side effects from internal radiation therapy are uncommon.
External beam radiotherapy with curative intent for localised prostate cancer should be given with six months hormone ablation therapy in all but the lowest risk groups. External beam radiotherapy and radical surgery are equally efficacious in curing localised prostate cancer.
The side effects of hormonal therapy depend largely on the type of treatment. Orchiectomy and LH-RH agonists often cause side effects such as impotence, hot flashes and loss of sexual desire. When first taken, an LH-RH agonist may make a patient's symptoms worse for a short time. This temporary problem is called "flare." Gradually, however, the treatment causes a man's testosterone level to fall. Without testosterone, tumor growth slows down and the patient's condition improves. (To prevent flare, the doctor may give the man an antiandrogen for a while along with the LH-RH agonist.) In some cases, men may be prescribed intermittent courses of hormone therapy, with careful monitoring by their doctor to determine when to begin the next course of treatment.
Antiandrogens can cause nausea, vomiting, diarrhea, or breast growth or tenderness. If used a long time, ketoconazole may cause liver problems, and aminoglutethimide can cause skin rashes. Men who receive total androgen blockade may experience more side effects than men who receive a single method of hormonal therapy. Any method of hormonal therapy that lowers androgen levels can contribute to weakening of the bones in older men.
During and after treatment, the doctor will continue to follow the patient. The doctor will examine the man regularly to be sure that the disease has not returned or progressed, and will decide what other medical care may be needed. Followup exams may include x-rays, scans, and lab tests, such as the PSA blood test.
Support for men with prostate cancer
Living with a serious disease such as cancer is not easy. Some people find they need help coping with the emotional as well as the practical aspects of their disease. Patients often get together in support groups, where they can share what they have learned about coping with their disease and the effects of treatment. Patients may want to talk with a member of their health care team about finding a support group.
People living with cancer may worry about caring for their families, keeping their jobs, or continuing daily activities. Concerns about treatments and managing side effects, hospital stays, and medical bills are also common. Doctors, nurses, dietitians and other members of the health care team can answer questions about treatment, working, or other activities. Meeting with a social worker, counselor, or member of the clergy can be helpful to those who want to talk about their feelings or discuss their concerns. Often, a social worker can suggest resources for help with rehabilitation, emotional support, financial aid, transportation, or home care.
It is natural for a man and his partner to be concerned about the effects of prostate cancer and its treatment on their sexual relationship. They may want to talk with the doctor about possible side effects and whether these are likely to be temporary or permanent. Whatever the outlook, it is usually helpful for patients and their partners to talk about their concerns and help one another find ways to be intimate during and after treatment.
Booklets and other useful materials are available from the Cancer Information Service and through other sources listed in the "National Cancer Institute Information Resources" section.
The Cancer Information Service can also provide information to help patients and their families locate programs and services.
news://alt.support.cancer.prostate is a newsgroup quite active with men currently dealing with the disease.
- http://www.malecare.com nonprofit prostate cancer website updated weekly
- http://www.phoenix5.org not updated since death of owner in 2001.
- http://www.cancer.prostate-help.org// largest patient supported non-commercial website for all aspects of prostate cancer
The promise of prostate cancer research
Doctors all over the country are conducting many types of clinical trials (research studies) in which people take part voluntarily. These include studies of ways to prevent, detect, diagnose, and treat prostate cancer; studies of the psychological effects of the disease; and studies of ways to improve comfort and quality of life. Research already has led to advances in these areas, and researchers continue to search for more effective approaches.
People who take part in clinical trials have the first chance to benefit from new approaches. They also make important contributions to medical science. Although clinical trials may pose some risks, researchers take very careful steps to protect people who take part.
A man who is interested in being part of a clinical trial should talk with his doctor. He may want to read Taking Part in Clinical Trials: What Cancer Patients Need To Know and Taking Part in Clinical Trials: Cancer Prevention Studies. These NCI booklets describe how research studies are carried out and explain their possible benefits and risks. NCI's Web site at http://cancer.gov provides general information about clinical trials. It also offers detailed information about specific ongoing studies of prostate cancer by linking to PDQ®, a cancer information database developed by the NCI. Causes
Although researchers know several risk factors for prostate cancer, they still are not sure why one man develops the disease and another doesn't. (Known risk factors, which include aging, are listed in the "Prostate Cancer: Who's at Risk?" section.)
Some aspects of a man's lifestyle may affect his chances of developing prostate cancer. For example, some evidence suggests a link between diet and this disease. These studies show that prostate cancer is more common in populations that consume a high-fat diet (particularly animal fat), and in populations that have diets lacking certain nutrients. Although it is not known whether a diet low in fat will prevent prostate cancer, a low-fat diet may have many other health benefits.
Some research suggests that high levels of testosterone may increase a man's risk of prostate cancer. The difference between racial groups in prostate cancer risk could be related to high testosterone levels, but it also could result from diet or other lifestyle factors.
Researchers also are looking for changes in genes that may increase the risk for developing prostate cancer. They are studying the genes of men who were diagnosed with prostate cancer at a relatively young age (less than 55 years old) and the genes of families who have several members with the disease. Much more work is needed, however, before scientists can say exactly how changes in these genes are related to prostate cancer. Men with a family history of prostate cancer who are concerned about an inherited risk for this disease should talk with their doctor. The doctor may suggest seeing a health professional trained in genetics.
Several studies are under way to explore how prostate cancer might be prevented. These include the use of dietary supplements, such as vitamin E and selenium. In addition, recent studies suggest that a diet that regularly includes tomato-based foods may help protect men from prostate cancer.
The drug finasteride is being studied in the Prostate Cancer Prevention Trial, which involves thousands of men across the country who are participating for 7 years, until 2004.
Scientists are also looking at ways to prevent recurrence among men who have been treated for prostate cancer. These approaches involve the use of drugs such as finasteride, flutamide, and LH-RH agonists. Studies have shown that hormonal therapy after radiation therapy or after radical prostatectomy can benefit certain men whose cancer has spread to nearby tissues.
Researchers also are investigating whether diets that are low in fat and high in soy, fruits, vegetables, and other food products might prevent a recurrence. For example, the Adventist Health Study found that meat-eaters had a 54% increased risk for prostate cancer when compared with vegetarians, even after adjusting for age, sex, and smoking (source: American Dietetic Association. 2003. Position paper on vegetarian diets. J Am Diet Assoc, 103, 748-765). The Cancer Information Service can provide information about these studies.
In July, 2003, an Australian research team lead Graham Giles of The Cancer Council released a report of a medical study that concluded that frequent masturbation by males may be an effective preventative measure. It was speculated by the researchers that the resulting ejaculations helps remove carcinogens from the gland area.  A subsequent study from the Health Professionals Study found no link between the two .
Due to old and limited studies, it was thought that increased levels of sexual activity led to an increased risk of prostate cancer. The results of a much larger study published in The Journal of the American Medical Association seem to suggest the opposite, however. Culminating in 2004, the study found that men who ejaculated (through sexual activity or masturbation) 21 times or more a month had decreased levels of occurrence. This was true across all age groups.
Researchers are studying ways to screen men for prostate cancer (check for the disease in men who have no symptoms). At this time, it is not known whether screening for prostate cancer actually saves lives, even if the disease is found at an earlier stage. The NCI-supported Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial is designed to show whether certain detection tests can reduce the number of deaths from these cancers. This trial is looking at the usefulness of prostate cancer screening by performing a digital rectal exam and checking the PSA level in the blood in men ages 55 to 74. The results of this trial may change the way men are screened for prostate cancer. The Cancer Information Service can provide information about this trial.
Through research, doctors try to find new, more effective ways to treat prostate cancer. Many studies of new approaches for men with prostate cancer are under way. When laboratory research shows that a new treatment method has promise, cancer patients receive the new approach in treatment clinical trials. These studies are designed to answer important questions and to find out whether the new approach is safe and effective. Often, clinical trials compare a new treatment with a standard approach.
Cryosurgery is under study as an alternative to surgery and radiation therapy. The doctor tries to avoid damaging healthy tissue by placing an instrument known as a cryoprobe in direct contact with the tumor to freeze it. The extreme cold destroys the cancer cells.
Doctors are studying new ways of using radiation therapy and hormonal therapy. They also are testing the effectiveness of chemotherapy and biological therapy for men whose cancer does not respond or stops responding to hormonal therapy. In addition, scientists are exploring new treatment schedules and new ways of combining various types of treatment. For example, they are studying the usefulness of hormonal therapy before primary therapy (surgery or radiation) to shrink the tumor.
For men with early stage prostate cancer, researchers also are comparing treatment with watchful waiting. The results of this work will help doctors know whether to treat early stage prostate cancer immediately or only later on, if symptoms occur or worsen.
The original text of this article was taken from the public domain document NIH Publication No. 00-1576, which can be found at http://www.cancer.gov/cancerinfo/wyntk/prostate
Last updated: 10-11-2005 02:03:14