Prostate Cancer

Treatment

A variety of treatment options are available for prostate cancer. The specific treatment option your oncologist recommends will depend on the extent or stage of your cancer and will be influenced by consideration of the side effects and expected benefits of each treatment. Sometimes your physician will recommend a combination of treatments.

Watchful Waiting

If your cancer is in an early stage and is estimated to grow slowly, your physician may recommend monitoring your condition without any treatment unless the cancer progresses. This approach is very safe for low-stage, low-grade tumors and avoids unnecessary and sometimes harmful treatments. Also called active surveillance, watchful waiting allows your doctor to monitor your prostate-specific antigen (PSA) levels and provide a digital rectal exam (DRE) regularly. If your PSA rises sharply or your DRE changes, your doctor may need to biopsy your prostate again.

Surgery

The type of surgery your urologist or oncologist recommends depends on the stage of the disease and your general health (see Table 2, page 48). The most common surgery for prostate cancer is a radical prostatectomy, or complete surgical removal of the prostate along with some surrounding tissue. A radical prostatectomy may be done as an open procedure through an incision in the body or laparoscopically with and without robotic assistance. Laparoscopic or robotic prostatectomy are much less invasive than an open procedure because they are performed through small, keyhole incisions in the body. Another minimally invasive approach is cryosurgery (also called cryotherapy or cryoablation), which kills cancer cells in the prostate by freezing the cells using a metal probe inserted through a small incision in the area between the scrotum and rectum.

Radiation

Radiation therapy uses beams of radiation to kill cancer cells. The radiation may be administered externally, called external-beam radiation therapy (EBRT) often using intensity-modulated techniques, referred to as Intensity-Modulated Radiation Therapy (IMRT) to assure delivery of high doses of irradiation to the prostate while sparing as much as possible normal surrounding tissues. IMRT external beam irradiation is generated from a machine outside the body; radiation may also be given internally, called brachytherapy, from radioactive seeds placed near the tumor inside the prostate. Many medical centers use three-dimensional conformal radiation therapy (3-D CRT) to determine the exact location and shape of the tumor. Both EBRT and IMRT focus a beam of high-energy radiation directly on the tumor to minimize radiation exposure to surrounding tissue and organs. Radiation oncologists may also use CT scans, magnetic-resonance imaging (MRI) and other imaging technologies during radiation therapy to improve the accuracy and precision of the therapy, a technique called image-guided radiation therapy (IGRT). In brachytherapy, the radioactive seeds give off either high-dose radiation for hours or low-dose radiation for weeks to the tumor. Low-dose seeds may be left in the prostate permanently.

Hormone Therapy

The prostate gland and prostate cancer are stimulated by male sex hormones, known as androgens, the most common being testosterone. Hormone therapy is designed to reduce the supply of male hormones to prostate cancer cells. Known as androgen-deprivation therapy (ADT), it is used in combination with surgery or irradiation to treat prostate tumors that are at high risk of spreading or returning after treatment or are widespread at the time of diagnosis. ADT may be accomplished surgically with the removal of testicles (surgical castration) or with drugs. The drugs used in ADT include LHRH (luteinizing hormone-releasing hormone) analogs and LHRH antagonists, anti-androgen drugs, the female hormone estrogen or combinations of LHRH analogs and anti-androgen drugs.

Chemotherapy

Chemotherapy drugs are reserved for patients who have hormone-resistant prostate cancer, recurrent or advanced prostate cancer or metastatic prostate cancer. The drugs are used to either kill the cancer cells or stop them from growing. Docetaxel is the most commonly used chemotherapy drug for prostate cancer. It is given in combination with the steroid prednisone. The combination has been shown to improve survival in men with advanced prostate cancer. The Food and Drug Administration (FDA) has approved docetaxel for use in men who are hormone resistant. The FDA has approved another drug, cabazitaxel, for advanced, hormone-resistant prostate cancer patients who have failed docetaxel treatment. Mitoxantrone, a drug that helps control symptoms of prostate cancer, is FDA approved and may be helpful in some men. In addition, studies have shown the chemotherapy drugs paclitaxel and estramustine to have some benefit in treating men with advanced prostate cancer.

Immunotherapy

Immunotherapy, sometimes called biologic therapy, is aimed at boosting the body’s immune system to fight cancer. Sipuleucel-T (Provenge) is the first immunotherapy approved by the FDA for the treatment of metastatic, hormone-resistant prostate cancer in patients with few or no symptoms. Sipuleucel-T is tailored to individual patients. Before treatment, blood is drawn from the patient and immune cells in the blood are separated out, modified in a laboratory and then returned to the patient. With these enhanced immune cells that target prostate cancer cells, the patient’s restored immune system is better able to kill the cancer cells.

Targeted Therapy

Targeted cancer therapies block the growth and spread of cancer by interfering with specific genes or proteins involved in tumor growth and progression. Cancer-targeted drugs interfere with the signaling process necessary for a tumor to grow. A number of targeted-therapy drugs are under investigation for the treatment of advanced, hormone-resistant prostate cancer. Drugs called selective endothelin-A receptor antagonists are among those being studied. They work by blocking the ability of cancer cells to use protein-bound endothelin-A receptors in the body to allow the cancer to progress. Monoclonal antibodies are also under study as targeted therapies for hormone-resistant prostate cancer. The antibodies are substances made in a lab to block the activity of a specific target on the surface of a cancer cell and stimulate the body’s immune system to fight the cancer. The antibodies may also be infused with radioactivity to kill cancerous cells. Researchers are also investigating two drugs known as MDV3100 and abiraterone as treatments for advanced prostate cancer. These drugs work by blocking testosterone from binding to the androgen receptor, thereby preventing the receptor from binding to DNA or by inhibiting the manufacture of male hormones in the testes and other tissues of the body. These drugs deprive the cancer cells of male hormones and thereby induce cancer cell death.

Other Treatments

Other treatments for advanced prostate cancer may include the drugs pamidronate and zoledronic acid, which reduce bone complications due to metastatic prostate cancer, such as pain and fractures, by reducing the level of calcium in the blood.

In addition, the radioactive agents strontium and samarium may be injected in the area of bone pain resulting from metastatic cancer to shrink the tumor and help relieve pain.