A Decade of Prostate Cancer Progress

Prostate cancer is the second most common cause of cancer-related deaths among American men.

The prostate is a gland in the male reproductive system. It makes most of the semen that carries sperm. The walnut-sized gland is located beneath the bladder and surrounds the upper part of the urethra, the tube that carries urine from the bladder.

Prostate cancer is frequently a very slow growing disease, often causing no symptoms until it is in an advanced stage. Most men with prostate cancer die of other causes, and many never know that they have the disease. But once prostate cancer begins to grow quickly or spreads outside the prostate, it is dangerous. While the disease is rare before age 50, experts believe that most elderly men have traces of it.

A Decade of Drugs on the Market

This year marks the tenth anniversary of the approval of docetaxel, the first chemotherapy for metastatic prostate cancer that showed a survival benefit. FDA approved docetaxel in 2004 after years of research failed to find a treatment that would prolong the lives of metastatic prostate cancer patients. Metastatic is a term used to describe a cancer that spreads from the original location to other areas of the body.

“When prostate cancer metastasizes to another location in the body, it is in most cases incurable, and the goal of treatment is to improve a patient’s symptoms or function or to extend the length of the patient’s life,” says Paul Kluetz, MD., acting deputy office director for FDA’s Office of Hematology and Oncology Products in the Center for Drug Evaluation and Research.

Since docetaxel, five additional therapies have been approved, and all of them have shown improvements in survival. Kluetz says it is unprecedented for so many drugs to demonstrate a survival advantage in an individual metastatic solid tumor setting.

Although the median extension of life for each of these approved drugs in metastasized prostate cancer is on the order of 2-6 months, it is hoped that when these drugs are used one after another, the survival benefit of each drug will be to some degree additive, particularly given that many of the drugs work through different mechanisms of action. The optimal order and combination is not yet known and will be an area of research over the coming years.

Moving Forward

One area of prostate cancer research that is garnering attention is related to patients whose cancer has not yet metastasized. Critical for this research will be the selection of patients who are at high enough risk of dying or becoming symptomatic from their prostate cancer to require treatment. Because of the widespread use of prostate-specific antigen (PSA) testing in the United States, prostate cancer is detected very early, and in some cases the prostate cancer found can be very slow growing.

“In early stages of prostate cancer relapse, either at first diagnosis or following initial treatment where PSA is increasing but there is not yet evidence of cancer in the bones or other organs, there is great interest in better defining who needs to be treated because many of these patients will go on to die of other natural causes prior to their prostate cancer becoming a problem,” Kluetz says.

Tests to identify patients at high risk for prostate cancer related death or morbidity are an area of intensive research. These tests have the potential to save many American men from the significant side effects of prostate cancer treatment which result in symptoms related to the removal or radiation of their prostate or severe reduction of androgens through either surgery or androgen deprivation drug therapy. These significant side effects highlight the need to reduce the burden to patients of overtreatment if the prostate cancer is slow growing.

Don’t Fall for Unproven Products

As with most cancers, there are companies selling so-called “natural remedies.”

Men with prostate problems who rely on these “remedies” rather than approved treatments may delay or forego getting the proper diagnosis and treatment says Gary Coody, FDA’s national health fraud coordinator in the Office of Regulatory Affairs.

A wide variety of prostate supplements are sold online and in retail stores with unapproved claims, such as:

• “shrink enlarged prostate”
• “treat benign prostate hypertrophy”
• “lower or slow rise in PSA levels”
• “decrease or slow prostate cancer growth”

FDA has issued warning letters to firms for marketing supplement products with these claims. The products have not been proven safe and effective for these purposes and may include the following ingredients: saw palmetto, beta sitosterol, pygeum, stinging nettle cranberry and others.