A study that analyzed the long-term safety and effectiveness of trastuzumab - more commonly known as Herceptin - found it significantly improves long-term survival of patients with HER-2 positive breast cancer when combined with chemotherapy.

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A new study shows that Herceptin improves long-term survival of patients with HER2-positive breast cancers.

The study, published in the Journal of Clinical Oncology, analyzed data from two independent trials designed to examine overall survival of patients with early-stage HER2-positive breast cancer who received chemotherapy with and without Herceptin.

The authors note that over 4,000 patients with HER2-positive operable breast cancer were enrolled and given "doxorubicin and cyclophosphamide followed by paclitaxel with or without trastuzumab in both trials."

Study co-author Charles E. Geyer Jr., physician-researcher at Virginia Commonwealth University (VCU) Massey Cancer Center in Richmond and professor in the Division of Hematology, Oncology and Palliative Care at the VCU School of Medicine, says:

"We have found that when Herceptin is used in combination with chemotherapy, a patient's survival is significantly improved."

"There are minimal long-term side effects, and the likelihood of the cancer recurring is greatly reduced," he adds.

The two trials that the study follows up are the same ones whose early results led the Food and Drug Administration (FDA) in 2006 to approve Herceptin as an adjuvant treatment for HER2-positive breast cancers.

10-year survival improved from 75% to 84% with Herceptin

The new analysis - which looked at overall survival rates up to 10 years after treatment - specifically addressed whether or not patients experienced a return of their cancer and whether any cardiac side effects were harmful enough to negate any benefits of treatment.

The results show that the 10-year survival for HER2-positive breast cancer patients who received chemotherapy without Herceptin was 75%, whereas for those who also had Herceptin, it was 84%.

The results also show improvement in disease-free survival. In patients who received chemotherapy without Herceptin, the 10-year disease-free survival rate was 62%, compared with 74% in those who also had Herceptin.

As to cardiac side-effects - a known risk for Herceptin patients - the incidence was found to be around 3%, and most of the patients affected recovered from the initial effects.

Herceptin is primarily used alongside chemotherapy to treat breast cancer patients whose cancer is HER2-positive. This type of breast cancer is often more aggressive than other types.

Up to 20% of breast cancers are due to HER2

HER2 - or human epidermal growth factor receptor 2 - refers to the HER2 gene and its associated protein. The protein helps to control the growth of healthy cells. But if the HER2 gene is amplified, or the protein is over-expressed, the cells can grow uncontrollably and lead to cancer.

Up to 20% of invasive breast cancers are a result of HER2 gene amplification or overexpression of HER2 protein.

The two trials behind the study were supported by the National Cancer Institute. Funds for the long-term follow-up study came from National Institutes of Health grants, the Breast Cancer Research Foundation, Genentech (the developers of Herceptin) and the Cancer and Leukemia Group B.

In July 2014, Medical News Today reported how researchers discovered a new target for the treatment of a particularly aggressive breast cancer. The molecule concerned - known as αvβ6 - could also identify patients with HER2-positive breast cancer who have a higher risk of developing secondary tumors.