HER2 positive breast cancer
Each year in New Zealand, more than 400 women are diagnosed with HER2-positive breast cancer.
HER2 stands for 'human epidermal growth factor receptor-type 2'. It is a type of protein that sits on the surface of all normal cells and its job is to send messages to the cell, telling it to grow and reproduce. In HER2-positive breast cancer, cells may reproduce very quickly.
If you have HER2-positive breast cancer, you have an abnormally large number of HER2 proteins on the cancer cells. This means the tumour has the potential to grow and spread at a much faster rate.
There are many types of treatment available for the different types of breast cancer, including the targeted drug treatment, Herceptin which is particularly effective for women with HER2-positive breast cancer.
A 12-month treatment programme of Herceptin has been available in New Zealand for women with HER2-positive breast cancer since 2008.
Some facts about HER2 Positive breast cancer and Herceptin
- Her2 Positive breast cancer is aggressive. On average across all types of breast cancer, 80 per cent of women will be alive 10 years after diagnosis. In comparison, only 50 per cent 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.
- A study on early-stage HER2-positive cancer found that a one year treatment programme of Herceptin reduced the likelihood of the cancer returning by 52 per cent and the risk of death by 34 per cent at two years after completing treatment. Recent results showed that after four years of follow-up in this trial, Herceptin-treated patients still had a 52 per cent lower rate of cancer recurrence and a 35 per cent 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 nine weeks of Herceptin with chemotherapy or chemotherapy without Herceptin as post-surgical treatment. This trial used an unconventional chemotherapy regimen. After three 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 per cent of patients when Herceptin is given following chemotherapy, and up to 4 per cent 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.