Researchers from the Early Breast Cancer Trialists’ Collaborative Group (EBCTCG), which is led from Oxford Population Health, have found that giving more modern types of radiotherapy to the regional lymph nodes, significantly reduces breast cancer recurrences and deaths. The study, which is published in The Lancet, shows improved outcomes in women treated with radiotherapy since 1990. These benefits are on top of the proven benefits of surgery, chemotherapy, hormonal therapy and radiotherapy to the breast.
Patients with early breast cancer are often given radiotherapy after surgery to eradicate cancer cells that could, if untreated, lead to recurrence and death. This study assessed the effects of giving radiotherapy to lymph node regions near the breast.
The researchers collected long-term outcome data (in some cases extending to 40 years since diagnosis) on individual women with early breast cancer in 16 randomised controlled trials that compared regional lymph node radiotherapy with no regional node radiotherapy. They assessed whether or not the 14,234 patients who participated in the studies had experienced any recurrence of their breast cancer, or died, either from breast cancer or any other cause.
Key findings:
- In eight newer trials, starting in the period from 1990 to 2008, regional node radiotherapy reduced both recurrence rates and deaths from breast cancer by about one eighth;
- The absolute benefit was largest in women at highest risk of recurrence. For women with 1-3 positive lymph nodes the 15-year risk of dying from breast cancer was reduced by about 2-3% with one fewer death for every 37 women treated. For women with 4 or more lymph nodes involved, the absolute risk was reduced by 4-5% with one breast cancer death prevented for every 22 women treated;
- In eight older trials, which started during 1961 to 1978, regional node radiotherapy had little effect on recurrence or death from breast cancer.
Over the past 50 years, radiotherapy techniques have improved substantially. This study shows the effects of those improvements. The older regional node radiotherapy techniques in the 1960s and 1970s did not reduce death from breast cancer. In contrast, more modern regional node radiotherapy techniques had a real impact by reducing breast cancer mortality and recurrence.
Carolyn Taylor, Professor of Oncology at Oxford Population Health, and one of the paper’s authors, said ‘The results show that modern radiotherapy to regional lymph nodes improves survival for women with early breast cancer. Since radiotherapy has continued to improve since the trials in our study were performed, with better targeting to increase its effectiveness and to minimise exposure of nearby organs, it is likely that the benefits of regional lymph node radiotherapy may now be greater than our study suggests. These results can help clinicians and patients in shared decision making regarding the benefits and risks of different treatment options.’
Robert Hills, Professor of Medical Statistics at Oxford Population Health, speaking on behalf of the EBCTCG Secretariat, said ‘These results are testament to the hard work of the trial teams, who have continued to provide updated data on their trials, and, most of all, to the over 14,000 women who entered the studies. These new data are key to showing how evolving radiotherapy techniques have improved the outcomes for women with breast cancer.’
The EBCTCG is funded by Cancer Research UK with additional support provided by the Medical Research Council.