Many Options For Metastatic Prostate Cancer, But No Cure

Patients with metastatic prostate cancer -- cancer that has escaped the prostate gland and spread to lymph nodes, bones or organs -- have a variety of treatments available to them, but none can cure the disease.

The best that these patients can hope for is to take one or more of a number of drugs in sequence, hoping that each one will buy them some additional time, perhaps as long as three years or so.

"When prostate cancer is metastatic, the goal is to prolong life with a high quality of life," said Dr. Glenn Bubley, Director of Genitourinary Oncology at Beth Israel Deaconess Medical Center and associate professor of medicine at Harvard Medical School.

"Patients go from one therapy to the next seeing if they get a response for as long as they can, but right now there is no cure," he said.

Only about 10 percent of prostate cancer patients in the U.S. are diagnosed initially with metastatic disease. Most cases of metastatic disease show up after treatment with surgery or radiation. In these cases, it turns out that some cancer cells may have escaped the gland before the treatment. About 30 percent of patients who get treated with surgery or radiation see their cancer eventually come back, according to Bubley.

Metastatic patients are typically treated with drugs that act against androgens in the body.  One drug in a  class called LHRH analogs is called Lupron. These drugs reduce the level of androgens in the body. There is another group of hormonal therapies that block androgen receptors. These are called antiandrogens. One of this class of agents is called Casodex.

The first line of therapy is usually Lupron or another in its class. Side effects include loss of libido, weight gain, fatigue, hot flashes and bone loss. Casodex and drugs in its class preserve libido, but cause breast enlargement. Sometimes, the two can be given together. Some patients go on and off the drugs, allowing breaks from the side effects.

"These drugs can work for years," Bubley said.

Once drugs in these groups stop working, patients may go on another drug, ketoconazole, which inhibits the production of androgenic hormones by the adrenal gland. Bubley said about half of patients can buy a prolonged period of time on this drug.

There are two new second line hormones that are now in trials that look very promising. One, called abiraterone, is already approved for patients that have had chemotherapy. This agent more effectively decreases testosterone production within metastatic cancer cells. Another agent called MDV3100 is also in final clinical testing, and has another means of providing responses in these patients. MDV3100 very effectively blocks the biding of testosterone to the testosterone receptor.

When this treatment fails, patients can take estrogen, the female hormone.

"We're trying to learn to use all these hormonal agents to get a better response," Bubley said. "We're also trying to learn which agents work best in which patients."

After hormonal therapy, patients may try chemotherapy. Some patients have gained another eight to 10 months of life with chemo, according to Bubley. Taxotere (docetaxel) is the first chemo drug usually tried, but recently another agent called Jetvana (cabazitaxel) was also approved for patients after taxotere stops working.

Beyond these treatments, Bubley noted that the first cancer vaccine approved for the treatment of prostate cancer has been approved for prostate cancer. This treatment, called Provenge, has been effective in clinical trials. A recent study showed the vaccine, which harnesses the body's own immune system to fight the cancer, gave those on it an additional four months of life. There are other immune therapies being investigated for the treatment of prostate cancer.

Above content provided by Beth Israel Deaconess Medical Center. For advice about your medical care, consult your doctor.