Doctors are reporting their first success at improving survival among men with advanced prostate cancer by using a treatment that trains the immune system to fight tumors.
The approach is called a cancer vaccine, although unlike traditional vaccines, it treats disease rather than prevents it.
In a study of 127 men with advanced prostate cancer, those who got the vaccine lived an average of 4 1/2 months longer than those who were given placebo treatments. After three years, survival was 34% in the vaccine group and only 11% in the other.
"That's a huge difference. These are people who have relatively few options, with limited survival," said Dr. Eric Small of UC San Francisco, who led the study and will give its results at a prostate cancer research meeting that opens today in Orlando.
The meeting is intended to bring more muscle to fighting the disease, which is the most common non-skin cancer in American men. About 230,000 new cases and 30,000 deaths from it are expected this year.
The vaccine, called Provenge, doesn't work like chemotherapy, and its side effects typically are a couple of days of fever and chills, like what people feel when they are fighting a cold.
The vaccine combines a protein found in most prostate cancers with a substance that helps specialized immune system cells recognize cancer as a threat, just as they recognize and confront germs that enter the body.
The treatment is customized for each patient. Doctors collect these cells from a patient's blood, mix them with the vaccine, and then give the concoction back to the patient in three infusions over a month.
In the study, men treated with Provenge survived an average of 26 months compared with 21.4 months for those who received dummy vaccine.