Prostate Cancer

Prostate cancer is the most prevalent cancer diagnosed and the second leading cause of cancer-related death among men in the United States. The prostate is a 20-gram gland, which is located at the base of the bladder and surrounds the urethra and consists of five lobes; the anterior, posterio, median and right and left lateral lobes. Since the prostate is a gland, the most common type of cancer is called adenocarcinoma. Despite significant improvement of hormonal, chemical and radiation therapies, there is no cure for locally advanced or metastatic prostate cancer.

A new form of immune therapy has shown a significant survival benefit in men who have metastatic androgen-independent prostate cancer, when compared to patients receiving placebo. The treatment is called Provenge and is manufactured by Dendreon Corp. of Seattle. Provenge is called a vaccine, but unlike most vaccines, it is used not to prevent illness but to treat an already existing condition. The vaccine combines a protein that is found in most prostate cancer cells with a substance that helps the immune system recognize the cancer as a threat. The vaccine must be custom made for each patient individually. First, patients have their blood run through a machine for several hours in order to extract antigen presenting cells (APCs). These cells are then mixed with a protein called prostatic acid phosphatase (PAP) that is commonly found on most prostate tumors. The PAP is fused with another immune-stimulating substance called GM-CSF. The mixture is then returned to the patient in a one-hour infusion. This process is repeated three times over the course of a month. The basic idea is to alert the immune system that cells containing prostatic acid phosphatase, (i.e., prostate cancer cells) should now be attacked as if they were a foreign invader.