Medical Treatment for Prostate Cancer
Prostate cancer treatment depends on the stage of the disease and the patient's age and overall health. Elderly patients with minor symptoms, early stage cancer, or coexisting illness may be treated conservatively.
Watchful waiting (also called active surveillance) is a reasonable course of action for patients who are elderly, who are in poor health, or who have low-risk, early stage cancer. Untreated prostate cancer may take years to become problematic. During this time, the physician carefully monitors the patient's condition for any marked or sudden progression of the disease, which may signal the need for more aggressive treatment.
Hormone therapy for prostate cancer, also called androgen deprivation therapy (ADT) and androgen supression therapy, may involve luteinizing hormone-releasing hormone (LHRH) analogs, luteinizing hormone-releasing hormone (LHRH) antagonists, anti-androgens, and other androgen-supressing drugs (e.g., ketoconazole [Nizoral®]). These drugs block the production of testosterone, which prostate cancer cells use to grow.
Types of hormone therapy that are often used to treat prostate cancer include the following:
- LHRH analogs
- Goserelin (Zoladex®)
- Leuprolide (Eligard®, Lupron®, Viadur®)
- Triptorelin (Trelstar®)
- LHRH antagonists
- Abarelix (Plenaxis®)
- Degarelix (approved in December 2008)
- Histrelin (Vantas®)
- Bicalutamide (Casodex®)
- Flutamide (Eulexin®)
- Nilutamide (Nilandron®)
Viadur® is a matchstick-sized titanium pump inserted under the skin on the upper arm that delivers a constant rate of leuprolide for 1 year. A tablet located in one end of the implant draws moisture from surrounding tissue in the arm. The moisture exerts pressure within the device that steadily pushes medication from the other end.
The device is inserted under local anesthesia through a small incision. The incision must be kept dry for 24 hours and must remain bandaged for a few days. Strenuous physical activity should be avoided for 48 hours. The implant is removed after 12 months and a new device may be inserted.
Patients who are taking antiandrogens must have periodic liver function tests and should report symptoms such as nausea and vomiting, stomach pain, extreme tiredness, appetite loss, dark urine, and yellowing of the eyes to their physician immediately.
Side effects associated with hormone therapy include the following:
- Blood in the urine (hematuria)
- Enlargement of breast tissue (gynecomastia)
- Hot flashes
- Lack of energy
- Local reaction to insertion (e.g., bruising, burning, itching)
- Ureteral or bladder outlet obstruction
Research has shown that hormone therapy to treat prostate cancer may increase the risk for heart disease and diabetes in some patients, and that men with heart disease who undergo this treatment may have a higher risk for serious heart conditions, such as heart failure and heart attack.
Patients who begin hormone therapy may experience an increase in prostate cancer symptoms for approximately 2 weeks, due to a temporary increase in testosterone levels. Patients with advanced disease (e.g., large bone, bladder, or spinal cord tumors) may be unable to tolerate this increase in testosterone. Studies have shown that abarelix injection (Plenaxis®), which does not cause a surge in testosterone, can be used in some of these patients to relieve symptoms (e.g., bone pain, inability to urinate).
Abarelix may cause life-threatening conditions in some people, such as a drop in blood pressure; loss of consciousness; breathing problems (e.g., shortness of breath, wheezing); and swelling of the face, eyelids, tongue, or throat. Patients must be monitored by a physician for at least 30 minutes after each administration of the drug in case an adverse reaction does occur.
Treatment involves one injection into the buttocks every 2 weeks for the first month, and every 4 weeks thereafter. Blood tests are performed every 2 months to monitor the effectiveness of the drug.
Common side effects include the following:
- Abnormal breast enlargement (gynecomastia), breast tenderness and pain
- Back pain
- Hot flashes
- Increased urination
- Sleep disturbances
- Swelling of the legs and ankles (peripheral edema)
When other methods of lowering testosterone are ineffective, the female hormone estrogen may be used to decrease testosterone levels. Side effects of taking estrogen include an increased risk for blood clots and breast enlargement (gynecomastia).
In some cases, advanced prostate cancer cells can survive and grow despite hormone therapy. The Food and Drug Administration (FDA) has approved the chemotherapy drug docetaxel (Taxotere®) to treat this type of cancer, which is called hormone refractory prostate cancer.
Side effects include the following:
- Hair loss (alopecia)
- Low blood cell count (e.g., anemia, neutropenia)
In April 2009, the FDA approved sipuleucel-T (Provenge®) to treat metastatic hormone refractory prostate cancer that causes mild or no symptoms. In this type of hormone therapy, immune cells called CD54+ cells are removed from the patient's blood about 3 days before treatment using a process called leukapheresis. The cells are activated with a substance called granulocyte/macrophage colony stimulating factor and then administered intravenously in 3 doses approximately every 2 weeks. The goal of this treatment, which is called autologous cellular immunotherapy, is to stimulate the patient's immune system to fight prostate cancer.
Provenge can cause serious reactions and can increase the risk of stroke. Side effects may include the following:
- Difficulty breathing, wheezing
- High blood pressure
- Fever, chills
- Muscle and joint pain, muscle weakness
- Nausea, vomiting
To reduce the risk for infusion reactions, patients often are given a pain reliever and fever reducer, such as acetaminophen, and an antihistamine about 30 minutes before the IV infusion.
In April 2011, the FDA approved abiraterone acetate (Zytiga®) to treat metastatic, castration-resistant prostate cancer. This drug is used in combination with prednisone and in men have undergone chemotherapy. Side effects of Zytiga include:
- Abnormal heartbeat
- Cough, upper respiratory tract infection
- High blood pressure
- Joint or muscle pain
- Stomach upset, diarrhea
- Swelling (e.g., of the legs, feet or joints)
- Urinary problems (e.g., urinary tract infection [UTI], frequency)
Treatment for Bone Metastases
Zoledronic acid (Zometa®) is a bisphosphonate prescribed to treat hypercalcemiaexcess calcium in the bloodin prostate cancer patients who have bone metastases (secondary tumors in bone). Patients with hypercalcemia experience dehydration, fatigue, nausea, vomiting, confusion, and if untreated, may result in coma.
Bone metastases cause bone tissue to break down, which releases calcium into the bloodstream. Zoledronic acid increases bone density, decreases bone loss, and reduces the risk for fractures.
Patients must have completed at least one course of hormone therapy before starting this treatment. Doses are given intravenously for 15 minutes, every 3 to 4 weeks. A blood sample is taken before each treatment to monitor kidney function.
Zoledronic acid is not recommended for patients with severe kidney disease and should be used with caution in those with aspirin-sensitive asthma and those taking loop diuretics (e.g., hydrochlorothiazide).
Side effects usually are mild and temporary. Patients may experience the following:
- Constipation or diarrhea
- Joint, muscle, or bone pain
- Shortness of breath (dyspnea)
Other medications approved to treat metastatic castration-resistant prostate cancer include Xtandi (for men who have previously been treated with docetaxel) and Xofigo (approved in May 2013 to treat cancer that has spread to the bones but not to other organs). These drugs have demonstrated an ability to prolong survival in men with late-stage prostate cancer.
According to the FDA, Xofigo (radium Ra 223 dichloride) binds with minerals in bone and delivers radiation directly to the tumors, with little damage to surrounding tissue. Common side effects include nausea, diarrhea, vomiting, and swelling of the legs. Low blood cell counts (e.g., anemia, lymphocytopenia, leukopenia, thrombocytopenia, neutropenia) also may occur.