"For the first time there is a therapeutic strategy that provides survival benefit for patients with advanced, metastatic hormone-refractory prostate cancer," says Shi-Ming Tu, MD, lead author of the study and an assistant professor/assistant internist with M.D. Anderson Cancer Center''s department of genitourinary medical oncology. "Prostate cancer has a unique affinity for the bones. Most, if not all, patients develop bone metastases. Often, bone is the only site of metastasis and patients who die from prostate cancer tend to die from their bone metastases," says Tu.

"They also suffer from bone pains and other complications of skeletal involvement. Therefore, it may not be a surprise that treating the bone metastases successfully will improve clinical outcome," says Tu.

Most prostate cancers grow in response to testosterone, the major androgen (male hormone) in the blood. When prostate cancer spreads beyond the gland itself, doctors use hormonal therapy to lower the levels of testosterone. This often leads to a lowering of the PSA (prostate specific antigen) level, which is an indicator of the amount of cancer in the body. After a while, however, the cancer stops responding to hormone therapy, at which point it is called "hormone-refractory" or "androgen-independent". When prostate cancer reaches this phase, there are few effective treatment options.

Tu and his colleagues treated and studied 103 prostate cancer patients resistant to hormonal therapy who were receiving chemotherapy. After two or three cycles of chemotherapy, they randomly assigned 72 patients who were responding or stable to receive a common chemotherapy drug, doxorubicin, every week for six weeks with or without one dosage of another drug, strontium-89 (Sr-89).

Sr-89 is a radioactive substance that is sometimes used to treat bone pain caused by metastatic prostate cancer. It is injected into the bloodstream, where it is attracted to areas of bone containing cancer. The radiation it gives off kills the cancer cells and often relieves the pain.

The results of the study have sparked interest within the medical community ? 60% of all of the study participants had a 50% or greater reduction in PSA concentration for at least eight weeks, and 42% had an 80% or greater reduction. Surprisingly, half of the men treated who had bone pain claimed complete relief from pain after treatment.

The major finding, however, was an increased survival rate. Men with bony metastases and androgen-independent prostate cancer typically survive nine months or less. But after the follow-up, the average survival rate for all 103 men was 17.5 months.

While these findings are positive, others say they only point to the need for more research and that it is important not to immediately conclude that the use of Sr-89 is solely responsible for the largest increase in survival ? that other factors could play a role.

According to the American Cancer Society?s director of prostate and colorectal cancer control, Durado Brooks, MD, since the participants were randomly chosen, varying factors unique to each person may have contributed to treatment results. Brooks says that he?d like to see more research with "more scientifically controlled trials."

"This study is very intriguing and in some ways exciting because it may point us in the direction of a new approach to treat advanced prostate cancer that can improve both the life span and the quality of life," says Brooks.

Tu agrees, saying the study results need to be confirmed in another trial. The National Cancer Institute is reviewing a proposal from his team to perform a national, confirmatory phase III trial, Tu says. In the meantime, he says he will conduct additional studies using different types of chemotherapy followed by bone-targeted treatment.