Barcelona—Survival for patients with metastatic breast cancer has improved dramatically in the last 20 years, especially in the subgroup of patients with HER2-positive tumors, according to research presented at the 7th European Breast Cancer Conference (EBCC7). This improvement, the researchers suggest, is due to in creased use of anthracyclines and the rise of targeted therapies.
“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,” said lead author Marie Sundquist, from the Department of Surgery, County Hospital, Kalmar, Sweden, in a press release announcing the findings.
The study is a retrospective analysis of follow-up data of metastatic breast cancer patients who were diagnosed in Kalmar County since 1985, and this continuity is a strength of the study. “We have studied a consecutive population in a defined geographical area for a continuous period of 25 years,” noted Dr Sundquist.
The researchers collected patient and tumor data from patient records and the tumor registry, and survival curves were generated in 5-year intervals by tumor grade. Separate analyses were performed for patients with
ER/PR-positive and HER2-positive tumors; there were 557 patients in the entire study population.
Median survival for the complete study population increased from 10 to 22 months, respectively, in the first and last 5-year period. For patients with grade 3 tumors, the most aggressive type of breast cancer (n = 288), the median survival time increased from 10 months in the 1985-1990 time period to 17 months for the 2000-2004 period. The percentage of patients with grade 3 tumors surviving more than 3 years improved from 14% to 34%. For patients with grade 2 tumors, the median survival was 17 and 27 months, respectively, in those same time frames. Survival for patients with grade 1 tumors did not change over time.
Better Targeting, But at a Cost In looking at the HER2-positive subset, 40 patients treated before 2000 had a median survival of 14 months, and the same number diagnosed in the year 2000 or later survived for 21 months. And this improved survival is largely due to new therapies, Dr Sundquist noted.
“In the group of HER2-positive patients that had the most aggressive type of breast cancer (grade 3), 45% of those patients that received trastuzumab had survived more than 3 years and 30% more than 5 years,” she said.
In a follow-up interview, Dr Sundquist noted that HER2 testing is routine in Sweden in all invasive breast tumors. “In our hospital, we introduced this routine in 1996,” she said.
Even with better targeting of therapy, metastatic disease presents a complex decision-making process for patients and physicians. “Patients whose breast tumors 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 tumor burden, while others fail to respond to any therapy,” Dr Sundquist noted. “To explore and try to understand these mechanisms would make it easier to tailor the treatment for each individual patient.”
But tailored treatments will not come cheap. “These new targeted therapies will, at least in the beginning after their development, be very costly for healthcare systems,” Dr Sundquist said. “When the public health insurance authorities decide which costs to cover, it is important that they realize the cost-benefit ratio.” Despite these costs, these drugs “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.
