The study is the fourth large clinical trial to show that Herceptin plus chemotherapy significantly reduces risk of disease recurrence in early breast cancer. “The chemotherapy combinations we tested with Herceptin proved to be superior to the best available standard therapy for early breast cancer,” said Slamon, principal investigator for the study conducted by the Breast Cancer International Research Group (BCIRG).
The study enrolled 3,222 women from all over the world with early stage HER-2 positive breast cancer. Patients received one of three regimens: The standard therapy of Adriamycin and Carboplatin followed by Taxotere (ACT), the therapy plus one year of Herceptin (ACTH), and the therapy without Taxotere plus one year of Herceptin (TCH). Reduction in risk of disease recurrence, the study’s primary endpoint, was 51 percent in the ACTH study arm and 39 percent in the TCH arm.
The study also resulted in two other important findings. Researchers knew that giving Herceptin with Adriamycin resulted in heart damage in some patients, the most severe of which was congestive heart failure. It was theorised, however, that this damage was not long lasting. But the BCIRG study showed the cardiac toxicity was significant and still persisted for more than 18 months at the date of the last follow up, Slamon said. This is vital information for doctors and patients to have when deciding which treatment regimen to use.
The good news, Slamon said, is that Herceptin given with the chemotherapy combination that eliminates Adriamycin is still significantly superior to the best available chemotherapy alone, reducing risk of relapse by 39 percent. That gives physicians and patients worried about heart damage an additional option. “Women will have the information they need to decide if the risk is worth the benefit,” Slamon said.