Checkup

Breast Cancer Breakthrough

Treatment Combo Dramatically Reduces Recurrence of Early Disease

Dr. Edith Perez

On April 25, the National Cancer Institute released the results of two large clinical trials showing that a monoclonal antibody, trastuzumab (Herceptin®), given with chemotherapy reduced recurrence of breast cancer in women with HER-2 positive invasive disease by more than 50 percent.

"These findings are dramatic," says Mayo Clinic medical oncologist Dr. Edith A. Perez, who chaired one of the studies — the North Central Cancer Treatment Group (NCCTG) trial. "These data confirm that we now have a very potent weapon against the recurrence of cancer cells that overexpress HER-2, which tend to grow fast and are generally more likely to recur."

Perez, an internationally known breast cancer researcher and co-director of the Multidisciplinary Breast Clinic at Mayo Clinic in Jacksonville, started work on the study seven years ago.

"I knew in my heart that the study had to be positive," she said. "I just didn't have a clue that it would be so positive."

Past research had indicated that trastuzumab added to chemotherapy slowed tumor growth in patients with advanced or metastatic breast cancer. It seemed logical, Perez says, to wonder whether the monoclonal antibody might stop the cancer from recurring. Even so, the dramatic results astounded her.

"We have essentially changed the natural history of early invasive breast cancer with this intervention," says Perez. "We showed that we could decrease recurrence by 52 percent. That is the largest improvement we've seen in more than 30 years, and perhaps ever, in the treatment of breast cancer."

About 25 to 30 percent of breast cancers overexpress HER-2. These tumors tend to grow faster and are generally more likely to come back than tumors that do not overproduce HER-2. Trastuzumab is a monoclonal antibody designed specifically to attack the overexpressed protein. Monoclonal antibodies are used for other types of tumors, such as lymphoma, but this is the first one targeting breast cancer.

The two trials included more than 5,000 women with HER-2 positive breast cancer nationwide. The preliminary results showed that 15 percent of the women who had chemotherapy and trastuzumab after surgery got breast cancer again, while 33 percent who had chemotherapy only had a recurrence.

Perez says that women who have been diagnosed with early stage invasive breast cancer should be sure that their physicians have their tumors sent to appropriate laboratories to be tested for HER-2. Although it's been the standard at Mayo for several years, it's not being done everywhere. She also advises women to discuss the findings of these studies with their physicians and ask if there is other research being done from which they might benefit.

Moving forward, researchers will focus on finding other ways of attacking HER-2. They'll also be looking for other proteins and genes that may be important in breast cancer growth so they, too, can be targeted.

"We have not stopped our search, because we would like to cure breast cancer in our lifetime," says Perez.

Info:
Multidisciplinary Breast Clinic
(904) 953-0707
Trastuzumab Information

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