A new review of research showed that women with HER-2 positive breast cancer who were treated with trastuzumab, sold under the brand name Herceptin, lived two to 11 months longer without their disease progressing than women not treated with the medication.
"If you have metastatic breast cancer, discuss treatment options with your doctor."
This systematic review was led by Sara Balduzzi, a statistician at the University of Modena and Reggio Emilia in Italy.
The researchers searched the web for randomized, controlled trials of women on trastuzumab, and looked at survival and heart issues. They found seven trials that met their criteria and included 1,497 women in their analysis.
All of the women had HER-2 positive breast cancer. About one in five women with advanced breast cancer has this type. HER-2 is a protein on the surface of breast cells that encourages the growth and division of tumor cells, so this type of breast cancer is particularly aggressive.
Trastuzumab does not cure this cancer, but binds to these tumors, preventing the spread of the cancer for some time. Many women on trastuzumab suffer heart issues that cause them to immediately stop taking the medication.
The researchers found that after two years of starting the trials, overall survival for women on trastuzumab was higher than for women with HER-2 positive breast cancer not taking that medication. Most women on trastuzumab gained two to 11 months without further progression of the disease.
Trastuzumab was most effective when it was the treatment of choice or in combination with chemotherapy medications known as taxanes.
The researchers found that with chemotherapy, the standard therapy for this cancer, 300 of 1,000 women with HER-2 positive breast cancer survived at least two years, and about 10 developed heart problems. With trastuzumab, 373 of 1,000 women survived a minimum of two years, but 35 developed heart issues that meant they had to stop taking the medication immediately.
The heart issues that arose are usually reversible, Balduzzi and team noted.
These researchers found that when trastuzumab was combined with anthracyclines, another type of medication for cancer, the risk for heart issues was even greater.
Trastuzumab reduced death rates by one-fifth, but increased heart toxicity three to four times.
The authors of this review noted that there were issues with their research. First, the women knew if they were or were not receiving trastuzumab, and in some cases, the women were able to start taking the medication mid-study. Further, the studies reviewed used different doses of the medication, and the women were able to take the medication with various other regimens for their cancer.
In addition, while most women started treatment with trastuzumab while in remission (their cancer was not spreading), some women started receiving the medication while their cancer was progressing, and the authors did not know what effect the medication had at this later point in time.
In a press release, Lorenzo Moja, one of the review's authors, said, “We found that women survived longer and their cancer did not progress as quickly when they received trastuzumab.”
This study was published June 11 in The Cochrane Library.
The authors declared no conflicts of interest, with the exception of Valentina Guarneri, who has received grants from pharmaceutical companies not involved in the production of trastuzumab.
Trastuzumab is manufactured by Genetech.