NEW YORK -- A new vaccine, still in the trial stages, is showing promise in treating colon cancer.

Former Olympian Charles Bittick is used to leaving challengers in his wake. But now he's in the race of his life against his toughest opponent yet: Advanced colon cancer.

"Your mortality is shoved right in your face at the time you discover you have cancer," he says.

Most patients given Bittick's diagnosis would be treated with chemotherapy. Traditionally, vaccines are given after patients fail to respond to chemotherapy. Now some doctors believe they work best before chemotherapy.

Dr. Heinz-Josef Lenz of the University of Southern California says this is the first time that chemotherapy and immunotherapy have been combined in patients who are newly diagnosed with metastatic or advanced colorectal cancer.

"I think the interesting combination is that you try with the help of the patient's immune system to control the tumor and, at the same time, you help to kill the tumor cells with chemotherapy we know can be effective," explains Lenz.

This vaccine is a therapeutic one, and unlike current therapies it has few side effects. Its job is to jump-start the immune system of someone who is already sick. Doctors already know that the stronger the immune system, the better the response to chemotherapy.

Many in the medical community believe that vaccines are the future of cancer treatment. So far Charles Bittick is responding well to the treatment, and he's proving the competitor in him is alive and well.

"I don't let things get me down. It's not something that I can live with. I have to either be on top of it or very close."

The company that developed this vaccine is also testing it in patients with late-stage melanoma. There are also other drug companies that are testing their own vaccines for different type of cancers.

Once the trials are completed, the drug company will have to prove its safety and effectiveness to the Food & Drug Administration. So right now it's probably too early to predict when the vaccine will hit the market.

The clinical trials are taking place at several centers in the United States, including the Norris Cancer Center where Bittick is being treated.