Fact Sheet: Herceptin in the Treatment of
Early stage Her2 over-expressing  Breast Cancer

Dated: September 2007
Every year in New Zealand as many as 600 women are diagnosed with a type of breast cancer known as HER2-positive breast cancer. The cancer cells of this type have higher than normal levels of a protein on their surface called HER2. This protein is part of a pathway which stimulates the cancer to grow. Herceptin (also called trastuzumab) is a drug that targets this Her2 protein and can help stop the growth of HER2-positive breast cancer. Herceptin has been used to treat HER2-positive breast cancer in advanced stages for a number of years. Recent research indicates it is also beneficial in early stages of the disease and many countries are now providing Herceptin to treat early stage HER2-positive breast cancer.

• HER2-positive breast cancer cells have higher than normal levels of a protein on their cells called HER2 (Human epidermal growth factor receptor 2), which is responsible for transmission of growth signals into the breast cancer cell. This type of cancer tends to grow faster and is more likely to spread than breast cancer that doesn’t have so many HER2 receptors and is therefore called HER2 negative.
• On average across all types of breast cancer, 80% of women will be alive 10 years after diagnosis. In comparison, only 50% of women with HER2-positive breast cancer will be alive 10 years after diagnosis. The chance of survival for an individual patient depends on the nature and extent of the disease at diagnosis and the treatments provided.
  
• Herceptin is a manufactured antibody that binds to the HER2 receptor, and blocks the signals that would otherwise cause the cancer to grow. It is designed to specifically target and treat cancers that are HER2 positive.
• For several years, Herceptin has been an established part of treatment for patients with advanced HER2-positive cancer that has spread throughout the body. Adding Herceptin to chemotherapy increases the length of time until the cancer grows again and increases the duration of life.

• Recent studies have shown that Herceptin is also beneficial in patients with early-stage HER2-positive cancer, where the cancer is limited to the breast and underarm lymph nodes. Treatment of patients with early stage breast cancer aims not only to extend life, as in advanced cancer, but to cure the disease. Trials involving over 11,000 women with early-stage HER2-positive breast cancer show that Herceptin given with or after post-operative chemotherapy reduced the risk of the cancer recurring by up to half, compared with chemotherapy alone. After 2-4 years, more patients were free of disease and fewer had died among those who had received 1 year of Herceptin treatment than among those who had not. (Note from BCAC: the 11,000 figure quoted here is now over 12,000. The data has been updated since this fact sheet was written and more patient follow-up has been recorded).
  
• A study in early-stage HER2-positive cancer found that 1 year of Herceptin reduced the likelihood of the cancer returning by 52% and the risk of death by 34% at 2years after completing treatment.  Recent results showed that after 4 years of follow-up in this trial, Herceptin-treated patients still had a 52% lower rate of cancer recurrence and a 35% lower risk of death.  Because the follow up of patients on this trial has been relatively short, the effects over the longer term, including increases in total duration of life, are not yet known.
  
• In a small trial known as the FinHer (Finland Herceptin) study, 232 patients with early-stage HER2-positive breast cancer received either 9 weeks of Herceptin with chemotherapy or chemotherapy without Herceptin as post-surgical treatment. This trial used an unconventional chemotherapy regimen. After 3 years, more patients were free of disease in the group that received Herceptin but the trial was too small to allow detection of a statistically significant difference in survival between treatments.  The small number of patients treated in this trial and serious imbalances between the Herceptin and no Herceptin treatment groups, means the results must be interpreted with great caution and are less certain than for the multiple larger studies involving 12 months of Herceptin treatment.

• The side effects of Herceptin are generally mild, with the most common being flu-like symptoms, which usually occur shortly after the drug is given. More serious events, such as allergic reactions and breathing problems occur rarely.

• Significant heart problems develop in a few women. Heart failure has occurred in 0.6% of patients when Herceptin is given following chemotherapy, and up to 4% when given at the same time as taxane-based chemotherapy. In some cases specific drug treatment was required  but in most patients, heart function recovered after stopping Herceptin. The risk of heart failure is greater in women with previous heart problems. Patients must be checked for heart problems before receiving Herceptin and must have their heart function monitored during treatment.

• In many countries, regulatory approval agencies, which evaluate available clinical and cost effectiveness data for pharmaceutical treatments, have fast-tracked their assessments of Herceptin. The results of studies showing the benefits of Herceptin in early breast cancer were published as recently as October 2005, but further positive results have been presented over the last 2 years and already 24 of 29 OECD countries surveyed have approved funding for 1 year of Herceptin treatment in early stage breast cancer. As of 1st July 2007, New Zealand became the only country to fund only 9 weeks of treatment, based on the FinHer results.

• Since Herceptin has become available for treatment of HER2-positive breast cancer, testing for HER2 receptors is now a standard test required on all newly diagnosed breast cancers.

September 2007

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