Patients With Breast Cancer Who Skipped RNI Did Not Experience Increased Risk of Disease Recurrence

According to clinical trial results, patients whose breast cancer converted from lymph node-positive to lymph node-negative disease after neoadjuvant chemotherapy, skipping adjuvant regional nodal irradiation (RNI), did not experience an increased risk of disease recurrence or death 5 years after surgery. The trial results were presented at the San Antonio Breast Cancer Symposium, held December 5 through December 9, 2023.

Patients diagnosed with breast cancer that has already spread to regional lymph nodes may receive neoadjuvant chemotherapy. In certain cases, neoadjuvant chemotherapy can completely eradicate the cancer from the lymph nodes; however, there is no current established standard of care for how these patients should be treated after surgery.

“There is an active debate on whether these patients should be treated as patients with lymph node-positive disease—which is how they were diagnosed—or as patients with lymph node negative disease—which is how they present at the time of surgery,” said Eleftherios Mamounas, MD, MPH, chair of the NRG Oncology Breast Committee, professor of surgery at the University of Central Florida, and medical director of the comprehensive breast cancer program at the Orlando Health Cancer Institute, in a press release.

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RNI is a form of radiotherapy that is directed to lymph nodes under the breast and is intended to reduce the patient’s risk of disease recurrence post-surgery. If treated as patients with lymph node-positive disease, patients would be recommended to receive chest wall irradiation in addition to RNI after a mastectomy, or whole breast irradiation plus RNI after breast-conserving surgery. Patients whose disease is considered lymph node-negative would be eligible to skip RNI post-surgery.

“Some patients may prefer to skip RNI to avoid complications associated with the treatment, such as pain, fatigue, lymphedema, and its impact on breast reconstruction,” said Mamounas in the press release. “Therefore, it is important to evaluate whether this treatment can be safely omitted in this patient population.”

A phase 3 clinical trial was conducted to evaluate the impact of RNI on patients outcomes. The 1556 patients eligible for the trial were diagnosed with lymph node-positive, nonmetastatic breast cancer whose lymph nodes were cancer free after neoadjuvant chemotherapy and who had undergone either mastectomy or breast-conserving surgery. Patients were randomly assigned to either the no RNI arm (observation after mastectomy or whole breast irradiation after breast-conserving surgery) or the RNI arm (chest wall irradiation plus RNI after mastectomy or whole breast irradiation plus RNI after breast-conserving therapy).

Patients experienced similar outcomes whether they received adjuvant RNI or not. Approximately 91.8% of patients in the no RNI arm and 92.7% in the RNI arm were free of invasive breast cancer recurrences 5 years after undergoing surgery. Further, distant recurrence and overall survival rates were also similar between the 2 arms, with 93.4% of patients in each arm free from distant recurrence 5 years after undergoing surgery, of which 94% were in the no RNI arm and 93.6% in the RNI arm.

“Our findings suggest that downstaging cancer-positive regional lymph nodes with neoadjuvant chemotherapy can allow some patients to skip adjuvant RNI without adversely affecting oncologic outcomes. Follow-up of patients for long-term outcomes continues,” said Mamounas in the press release.

Reference

American Association for Cancer Research. Neoadjuvant chemotherapy may help some breast cancer patients skip regional nodal irradiation. News release. December 6, 2023. Accessed December 4, 2023. https://www.eurekalert.org/news-releases/1009893