The chances of breast cancer recurring remain very low when patients are treated with radiotherapy that is tailored to their individual risk following chemotherapy and surgery. These are the findings of a ten-year study presented at the 15th European Breast Cancer Conference (EBCC15) in Barcelona today (Wednesday).
In the study, radiotherapy treatment was selected according to whether there were still signs of breast cancer cells in patients' lymph nodes after chemotherapy and surgery. For women with no signs of cancer remaining in the lymph nodes, this approach meant minimal or even no radiotherapy. Scaling treatment down can in turn reduce side-effects for patients.
The research was presented by Dr Fleur Mauritz, a radiation oncologist in training at Maastro, Maastricht Radiation Oncology Institute, The Netherlands. She said: "For many patients with breast cancer, the first treatment is chemotherapy. This can shrink the tumor and kill off any cancer cells that are starting to spread into the body, before surgery.
"We know that radiotherapy reduces the risk of breast cancer recurrence, especially when patients have had surgery to remove a tumor, rather than the whole breast, and when there are signs of cancer in the lymph nodes. This study examined whether it's possible to scale back radiotherapy in patients whose cancer shows a good response when chemotherapy is given prior to surgery."
The study included 848 patients who were treated at 17 cancer centres in The Netherlands between 2011 and 2015. Each patient had a small breast tumor (measuring under five centimetres) with signs of cancer spread in only one, two or three lymph nodes.
Following chemotherapy and surgery, the patients were categorised into three different risk groups. Patients who no longer had signs of cancer in their lymph nodes were categorised as low risk and were given radiotherapy to the breast if their surgery removed the tumor, or no radiotherapy if they had their breast removed (mastectomy). Patients who had signs of cancer in only one to three lymph nodes were categorised as intermediate risk and treated with radiotherapy to the breast area without irradiating the nearby lymph nodes. Patients with signs of cancer in four or more lymph nodes, were categorised as high risk and treated with radiotherapy to the breast area and the lymph nodes in the surrounding area.
In the following ten years, only 24 out of all 838 patients who completed follow-up (2.9%) experienced a recurrence in the breast, chest wall or lymph nodes (without signs of cancer spread elsewhere in the body). In the low-risk group, seven out of 291 patients (2.4%) developed a recurrence; in the intermediate-risk group, 12 out of 370 patients (3.2%) developed a recurrence; and in the high-risk groups five out of 177 patients (2.8%) developed a recurrence.
Dr Mauritz said: "The results of our study show that tailoring the extent of radiotherapy according to how well the chemotherapy has worked to treat cancer in the lymph nodes, leads to very low and reassuring recurrence rates in the breast and surrounding area. In a selected group of patients, we see very low recurrence rates even when we leave radiotherapy out completely.
"A major strength of our study is that it's the first to demonstrate the benefits of tailoring radiotherapy for this group of patients over a ten-year period. It is important to note that most patients in the study underwent axillary lymph node dissection, a procedure that was common ten years ago but is used less often in current practice. This study did not compare patients treated with and without radiation therapy. For the final conclusion, we will have to wait for the results of a randomized trial from the USA, which are expected in three years."
Dr Mauritz and her colleagues plan to study more about the risk factors for breast cancer recurrence, for example looking at tumor characteristics, and precisely where cancer recurs, to help refine radiotherapy in the future.
The Chair of EBCC15, Professor Isabel Rubio, Head of Breast Surgical Oncology at the Clínica Universidad de Navarra in Madrid, Spain, was not involved in this research. She said: "Reducing radiotherapy after chemotherapy appears safe in terms of the risk of recurrence. Choosing the amount of treatment based on the risk of recurrence also seems appropriate: radiotherapy may be omitted in low-risk patients after mastectomy, while in intermediate-risk patients, targeted radiotherapy remains advisable. Overall, this study reinforces that stratifying patients by risk, which supports more personalised treatment, helps to ensure the most appropriate approach while avoiding both overtreatment and undertreatment."
Dr Mauritz is delivering the young investigator innovation award lecture at EBCC15.
Tumor debulking fails to improve survival in colorectal cancer