Treatment options for prostate cancer.
After receiving a diagnosis of prostate cancer, a man will need to decide how aggressively to treat the cancer, weighing the severity of the disease against the risk of side effects. Since early prostate cancer tends to grow slowly, there is seldom a need to rush into a decision. Patients can take their time to talk to their doctor, decide if they need a second opinion and weigh their various treatment options.
Experts estimate that up to 60 percent of men diagnosed with prostate cancer may never require therapy. During active surveillance, doctors monitor the PSA level and check for signs the cancer is growing. Men commonly think that active surveillance means ignoring the cancer, but, in fact, it means paying special attention to it with PSA tests, exams and biopsies until a result triggers the need for treatment.
A 15-year study published recently in The New England Journal of Medicine found that men who chose to have their prostate removed versus men who opted for active surveillance, or watchful waiting, had no statistical difference when it came to prostate cancer mortality rates or overall death rates.
Another recent study found that patients with low-risk prostate cancer who choose active surveillance can decrease their risk of progression by exercising vigorously at least three hours a week. Active surveillance is the option with the fewest side effects.
Younger men, those with more aggressive cancer or those who simply feel that awareness of their cancer would cause them too much anxiety, may choose more immediate treatment. Surgery to remove the prostate, along with the nearby tissues and seminal vesicles, is an option for men whose cancer has not spread. One recent study suggests that men with PSA levels of greater than 10, as well as a higher-risk disease, might reduce their risk of mortality from the disease by having the prostate gland removed.
The two most common side effects of treatment are incontinence and impotence. If the cancer is not too entangled with the nerves that control erections, doctors can remove the prostate with less damage, lowering the risk of impotence. The surgeon’s expertise, particularly with nerve-sparing surgery, is key. It is too early to know whether sophisticated robotic surgery actually improves outcomes or side effects.
Since prostate cancer cells are fed by male hormones, drugs that lower them help to starve the cancer cells of their needed fuel. Androgen deprivation therapy (ADT) does not get rid of the cancer but can shrink it or make it grow slower.
Since early prostate cancer tends to grow slowly, there is seldom a need to rush into a decision.
Doctors will often prescribe ADT to reduce tumor size before surgery for men whose cancer has already spread beyond the prostate, for those whose cancer remains or has recurred after initial treatment, or for those who are at high risk for recurrence after radiation. Several types of hormone therapy are available, so patients should discuss the best option with their doctor.
For advanced prostate cancer, continuous therapy (associated with more side effects) as opposed to intermittent therapy has shown to produce better results, particularly in men with minimal metastases.
One recently approved hormone drug is Zytiga (abiraterone), an oral medication that has been found to improve survival in men with advanced prostate cancer who had previously received chemotherapy with docetaxel.
Xtandi (enzalutamide, MDV3100) prevents androgens from binding to and entering the tumor cells instead of lowering their levels. In one study, enzalutamide significantly slowed PSA progression and bone metastases. Side effects were mild and included fatigue, diarrhea and hot flashes.
For cancer that is limited to the prostate or nearby tissue, men may choose radiation therapy over surgery. The problem is that healthy tissue can get hit in the crossfire. Techniques, however, have become more refined, allowing doctors to focus more radiation on the tumor and less everywhere else. The most traditional form of radiation is called external beam radiation therapy (EBRT) in which radiation is delivered by a computer-guided machine that directs the radiation from outside the body to the prostate.
Another form of radiation is referred to as brachytherapy, or internal radiation therapy, in which doctors insert small radioactive pellets into the tumor. Radiation from the pellets (or seeds) does not travel far, so the technique can minimize radiation exposure to healthy tissues. This is often an option for low-grade prostate tumors. Brachytherapy has fewer side effects than EBRT and is less expensive than both EBRT and surgery, according to a comparison study.
Proton beam therapy uses proton particles instead of X-rays to kill the cancer cells. Researchers are still testing the pros and cons of this treatment, and with fewer than a dozen proton beam facilities nationwide, travel and treatment can be costly. A recent study shows it may be no better than traditional intensity modulated radiation therapy, a form of EBRT, and may have slightly more side effects.
Alpharadin (radium-223) is an experimental intravenous drug that uses a type of ionizing radiation to kill metastatic cancer cells that invade the bone tissue. In a recent study, it reduced the risk of death by nearly a third compared with men receiving best supportive care only.
Chemotherapy is used when the cancer has spread beyond the prostate and hormone therapy isn’t working. It cannot get rid of the cancer, but it might slow disease progression or reduce symptoms. The chemotherapy most commonly used is docetaxel, which is administered along with the steroid prednisone in advanced cancers that do not respond to hormone therapy. For men whose cancer continues to spread with docetaxel, a newer chemotherapy called Jevtana (cabazitaxel) can be prescribed.
Chemotherapy is used when the cancer has spread beyond the prostate and hormone therapy isn’t working.
Another drug, cabozantinib, which is an investigational targeted therapy that inhibits two growth pathways, delayed disease progression in men with prostate cancer that had spread to the bone. In a 2011 study, patients on cabozantinib had reduced bone pain and their disease progressed at a slower rate than patients who did not receive the drug.
Provenge (sipuleucel-T) is an individualized immunotherapy developed to target a patient’s tumor. In clinical trials, men with advanced cancer who received the vaccine lived about four months longer than patients who did not use Provenge. There are other immunotherapies in testing for prostate cancer, including the vaccine Prostvac-VF and the melanoma drug, Yervoy (ipilimumab).
Bisphosphonates, which inhibit bone mineral loss, can reduce bone pain and prevent or delay damage caused by metastatic tumors. Zometa (zoledronic acid), approved to treat bone tumors caused by prostate cancer, is considered the standard of care for bone metastases from prostate cancers that resist therapies—such as surgical castration or ADT—that are aimed at quelling the impact of male hormones. Bisphosphonates, especially when given intravenously, have been linked to a serious condition known as osteonecrosis of the jaw, or ONJ.
Xgeva (denosumab), while not a bisphosphonate, is a drug that also helps protect bone tissue in patients with metastatic prostate cancer.
Editor's note: This article has been updated from its original printed version to reflect the approval of Xtandi (enzalutamide) on Aug. 31, 2012.