CHICAGO, Jan. 25, 2006 — -- Four years after she was diagnosed with an aggressive form of breast cancer, Peggy Matson is now free of the disease.
She had surgery and took a new drug called Herceptin, one of the first medications to attack breast cancer cells specifically.
"I happened to be diagnosed at a time when there was a drug that increased my chances for survival dramatically," Matson said. "It's like winning the lottery."
While Herceptin is considered a major breakthrough, it works on only 20 percent of breast cancers. New therapies, now in final clinical trials, show even more promise.
"When I'm talking to patients, I tell them we may not have a cure for breast cancer today, but that I believe it's right around the corner, said Dr. Kimberly Blackwell, assistant professor of medicine at Duke University Medical Center.
Researchers now know that breast cancer is actually a number of different diseases. That discovery has led to the development of several new treatments that target specific types of tumors in the breast.
One of the most promising is a pill called Lapatinib, potentially more effective than Herceptin because it inhibits the growth of two proteins in certain cancer cells, while Herceptin affects only one.
"What a drug like Lapatinib is doing once it's inside the cancer cell is putting on the brakes," said Dr. Eric Winer, chief of the breast oncology center at the Dana-Farber Cancer Institute in Boston.
Since it attacks just the cancer cells, there are fewer side effects.
Researchers are also optimistic about another drug, Avastin, which has already prolonged the lives of patients with advanced colon cancer.
In breast cancer trials, Avastin has been effective at choking off the blood supply that tumors need to grow and spread. It is now being tested on women who are newly diagnosed.
"Our hope really is that in those early-stage patients this will prevent recurrences and ultimately cure more women of breast cancer," said Dr. Kathy Miller at the Indiana University Medical Center.
Terry Farrer was diagnosed with breast cancer three times. She began Avastin treatment two years ago.
"I've gone from not thinking that I'd see my youngest go to kindergarten to watching him play football and basketball," she said.
This time, she hopes her cancer is gone for good.
ABC News' Barbara Pinto filed this report for "World News Tonight."