Can breast cancer be cured without surgery or chemo? That's what a groundbreaking new study by the Lester and Sue Smith Breast Center at Baylor College of Medicine suggests.

A just-released clinical study at the Smith Breast Center showed that a significant percentage of participants with HER2-positive breast cancer had their tumors completely or mostly eradicated using a combination of drugs. Tumors positive for HER-2, or or human epidermal growth factor receptor 2, account for approximately a quarter of all breast cancers and tend to be particularly aggressive.

Led by Dr. Mothaffar Rimawi, medical director of the Smith Breast Center, and Dr. Jenny Chang, director of the Methodist Cancer Center, the study included 64 women who had advanced HER2-positive tumors and for whom the typical course of treatment would be a round of chemotherapy, followed by surgery and then more chemo.

"HER-2 is a major driver, it's the engine that keeps the cancer growing," Rimawi says. "Chemo targets any proliferating cell — that's why it causes hair to fall out, lowers the immune system, creates nausea. This targets the particular molecule in two different ways and blocks it completely from partnering with other molecules, so it essentially shuts down the main driver."

For 12 weeks the women received a daily dose of the drug Lapatinib, which blocks the HER-1 and HER-2 enzymes, and a weekly intravenous dose of trastuzumab, an antibody which uses another method to block the HER-2 protein. Both drugs have been used individually, but doctors had no idea how effective they would be when combined in treatment.

The results were nothing less than unprecedented: 38 percent of estrogen-receptor-negative patients had their breast cancer eradicated. Among patients with estrogen-receptor-positive cancers, 21 percent had their cancers completely disappear and another 34 percent had almost all the cancer gone.

"I think this is groundbreaking," Rimawi says. "These patients responded dramatically. If you look at what we saw, it is what we expected, but every time you see something from the lab translating into real life, into patients, that's special because a lot of time those don't translate. One of the things that surprised me was the rapidity in which they responded. The results for this subgroup are quite remarkable."

Study patient Maryann McCormick says the decision to participate was easy for her.

"When I was told I qualified for the trial, they explained it to me, and I felt I had everything to gain and nothing to lose," McCormick says. "I had an eight centimeter tumor and aggressive stage three cancer. After 12 weeks it was less than two centimeters. It was the best thing I ever did."

McCormick still underwent a mastectomy, but her course of chemotherapy was reduced from 16 rounds to six rounds.

"I think this is provocative both for this kind of cancer, and as the model we should be after for new treatments," Rimawi says. "Let's find out what drives every subset of cancer, not just breast cancer, but all cancers, target them and shut them down. This is what personalized medicine should be about, a personalized approach to understand the patient and the tumor and find what works for them.

"We need to apply that to other cancers and other tumors. Some areas have started looking at cancer like this and in other areas there is more work needed."

The next phase of study for the drug-based treatment is to study the effects on smaller tumors and determine the optimum duration of treatment, whether it is 12 or 24 weeks. In June, Dr. Chang will present the finding of the study in Chicago at the American Society of Clinical Oncology meeting.

Editor's note: Stay tuned for CultureMap special series on the fight against breast cancer, starting Monday.