Neoadjuvant Chemotherapy Could Help Patients With Breast Cancer Skip Regional Nodal Irradiation

Skipping adjuvant regional nodal irradiation (RNI) does not increase the risk of disease recurrence or death 5 years after surgery for individuals with breast cancer converted from lymph node positive to lymph node negative after adjuvant chemotherapy, according to results of the NRG Oncology/NSABP-B-51/RTOG 1304 trial (NCT01872975). The data were presented at the 2023 San Antonio Breast Cancer Symposium in Texas.

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Neoadjuvant therapy is used to eradicate cancer from the lymph nodes, and patients with breast cancer that has spread to the regional lymph nodes could be eligible for neoadjuvant chemotherapy. According to Eleftherios “Terry” Mamounas, MD, MPH, there is no established standard of care for individuals whose breast cancer has spread to the lymph nodes.

“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,” Mamounas, chair of the National Surgical Adjuvant Breast and Bowel Project, the Radiation Therapy Oncology Group, and the Gynecologic Oncology Group (NRG) Oncology Breast Committee and medical director of the Comprehensive Breast Program at the Orlando Health Cancer Institute in Florida, said in a press release.

RNI is a form of radiation therapy directed at the lymph nodes to reduce the patient’s risk of disease recurrence after surgery. Typically, patients treated for lymph node–positive disease would undergo chest wall radiation with RNI after mastectomy or whole-breast irradiation plus RNI after breast-conserving surgery. Mamounas added that some patients may skip RNI to avoid complications with the treatment, including pain, fatigue, lymphedema, and the impact on breast reconstruction. “Therefore, it is important to evaluate whether this treatment can be safely omitted in this patient population,” Mamounas said in the press release.

To evaluate the patient outcomes, Mamounas and colleagues conducted the NRG Oncology/NSABPB-51/RTOG 1304 phase 3 clinical trial, which enrolled 1641 individuals with lymph node–positive nonmetastatic breast cancer whose lymph nodes were cancer free after neoadjuvant chemotherapy and who underwent either mastectomy or breast-conserving surgery. Individuals were randomly assigned 1:1 to the non-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 surgery).

Investigators found that patients evaluated had similar outcomes regardless of RNI therapy, with 91.8% of those in the non-RNI arm and 92.7% in the RNI arm free of invasive breast cancer recurrences 5 years post surgery. Furthermore, distant recurrence and overall survival rates were also similar between arms, with 93.4% of individuals in each arm free of distant recurrence 5 years post surgery and 94% in the non-RNI arm and 93.6% in the RNI arm alive after 5 years.

“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,” Mamounas said in the press release. “Follow-up of patients for long-term outcomes continues.”

One limitation of the study included fewer breast cancer recurrences than expected, which affected the investigators’ ability to perform the planned statistical analyses based on the number of recurrences, according to the press release. Investigators added that the statistical plan of the study included analyses 10 years after initiation of the study, which was completed in 2023. The study investigators plan to conduct longer follow-ups to strengthen the analysis and results of the study.

Reference

Neoadjuvant chemotherapy may help some breast cancer patients skip regional irradiation. News release. San Antonio Breast Cancer Symposium. December 6, 2023. Accessed December 5, 2023. https://www.aacr.org/about-the-aacr/newsroom/news-releases/neoadjuvant-chemotherapy-may-help-some-breast-cancer-patients-skip-regional-nodal-irradiation/#:~:text=%E2%80%9COur%20findings%20suggest%20that%20downstaging,outcomes%20continues%2C%E2%80%9D%20Mamounas%20summarized