FOR PEOPLE WITH BREAST CANCER that has spread to the lymph nodes, standard treatment is surgery to remove the breast followed by chest radiation. Research supports this approach when the cancer has progressed to four or more lymph nodes, but when the disease has impacted fewer lymph nodes, the evidence for postsurgical radiation isn’t as clear.
Researchers set out to discover if people with intermediate-risk breast cancer require radiation, and with findings presented Dec. 12 at the San Antonio Breast Cancer Symposium, they suggest this population may be able to avoid the additional therapy.
In a phase III clinical trial, researchers followed 1,607 people with intermediate-risk breast cancer that either had spread to one to three lymph nodes or had not progressed to the lymph nodes but exhibited other characteristics that increase recurrence risk. After having surgery to remove the affected breast, 808 participants received chest wall radiation, while 799 people skipped radiation. A quarter of participants also took endocrine therapy.
After a median follow-up of 9.6 years, 82% of the participants who did not have radiation were alive, compared with 81.4% of those who received radiation. Just 29 people experienced a cancer recurrence—nine who had radiation and 20 who did not. That translates to a 98.8% recurrence-free survival rate at 9.6 years for those who had radiation, compared with 97.1% for people who did not. Researchers found both groups also had similar rates of disease- and metastases-free survival.
Based on these findings, “adjuvant chest wall irradiation should be omitted in most patients” who meet the trial’s eligibility criteria, said Ian Kunkler, a study author and a clinical oncologist at Edinburgh Cancer Centre at the University of Edinburgh in Scotland.
Researchers plan to do follow-up analyses to look at participants by age, node status and the molecular characteristics of their cancers to see if the results apply to all people and tumor types. “We’re not saying that this is applicable to all patients; I think it’s going to be applicable to most but certainly not to all,” Kunkler said in a press briefing at the conference.
Radiation to the chest can cause various side effects, including pain, scarring or stiffening of tissue, and long-term cardiovascular problems, so researchers asked participants to complete questionnaires about their symptoms and quality of life. In a 2018 analysis published in Lancet Oncology that looked at responses two years into this trial, participants who received radiation reported significantly worse chest wall symptoms, such as pain, swelling and skin problems, than those who were not given radiation. However, there was no difference between the groups in overall quality of life.
Kunkler said he feels this research could potentially be practice changing. “This is something that the guideline groups will have to look at very seriously,” he said. Until changes occur, he said, patients and providers should have discussions about the findings so they can decide if radiation is appropriate.
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