Trends indicate that survival is improving in patients with metastatic breast cancer, especially in those patients whose tumours are described as being HER2 (human epidermal growth factor receptor-2) positive, a surgical oncologist said on March 26 at the seventh European Breast Cancer Conference.
Dr Marie Sundquist, from the Department of Surgery, County Hospital, Kalmar, Sweden, said that the median survival times for five-year intervals of 557 metastatic breast cancer patients in Kalmar, Sweden, increased steadily, from 10 months for the 1985 to 1990 period, to 22 months for the 2000 to 2004 period.
She reported the findings of a retrospective analysis of follow-up data of breast cancer patients who were diagnosed in hospitals in Kalmar County since 1985. "A strength of our work is that we have studied a consecutive population in a defined geographical area for a continuous period of 25 years," Dr Sundquist will tell the conference.
Dr Sundquist tolddelegates that for 288 patients with grade III tumours, the most aggressive type of breast cancer, the median survival time increased from 10 months for the 1985 to1990 period to 17 months for the 2000 to 2004 period. The increased use of the chemotherapy drugs called anthracyclines and taxanes led to the improved survival outcomes in this group of patients with the aggressive form of metastatic breast cancer, she said.
Some breast cancer cells have receptors, which allow certain types of hormones or proteins to attach to the cancer cell. Breast cancer hormone-receptor status can affect the individual patient's treatment options as well as overall prognosis. Analysis of the data by HER2 positive status revealed that HER2 positive patients with metastatic breast cancer had improved survival rates. Prior to the year 2000, 40 HER2 positive patients had a median survival of 14 months compared to 21 months for 40 HER2 positive patients diagnosed with breast cancer from the year 2000 onwards.
Dr Sundquist said: "There is no doubt that trastuzumab (Herceptin), which targets the HER2 gene, is the most important reason for the improved survival in this group of patients, and use of the chemotherapy drugs known as anthracyclines also contributed.
"In the group of HER2 positive patients that had the most aggressive type of breast cancer (grade III), 45% of those patients that received trastuzumab had survived more than three years and 30% more than five years," Dr Sundquist added.
"Patients whose breast tumours have spread outside of the breast and armpit areas are essentially incurable. However, some patients live even decades with a good quality of life despite an initially widespread tumour burden, while others fail to respond to any therapy. To explore and try to understand these mechanisms would make it easier to tailor the treatment for each individual patient," Dr Sundquist said.
A new era of breast cancer treatment started with the gene-targeted therapy of trastuzumab. Since then, a number of similar targeted therapies including antibodies or inhibitors of specific genes have been developed. This will open new avenues in the treatment of all metastatic breast cancers and also of primary breast cancer.
"These new targeted therapies will, at least in the beginning after their development, be very costly for healthcare systems. On the other hand they will make it possible for many women to lead almost normal lives, work and contribute to society for an increased number of years," she concluded.
The researchers intend to follow up their work by performing genetic analyses of the tumours with different responsiveness to specific treatments. "Health care systems will need to provide tools for the routine clinical assessment of a number of genes related to treatment response," she added.
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