Role of Elective Nodal Irradiation in Patients With ypN0 After Neoadjuvant Chemotherapy Followed by Breast-Conserving Surgery (KROG 16-16)

• Published in: Clinical breast cancer Vol. 19; no. 1; pp. 78 - 86
• Main Authors: Cho, Won Kyung, Park, Won, Choi, Doo Ho, Kim, Yong Bae, Kim, Jin Ho, Kim, Su Ssan, Kim, Kyubo, Kim, Jin Hee, Ahn, Sung Ja, Lee, Sun Young, Lee, Jeongshim, Kim, Sang-Won, Kwon, Jeanny, Ahn, Ki Jung
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.02.2019
• Subjects: Antineoplastic Combined Chemotherapy Protocols - therapeutic use; Breast neoplasm; Breast Neoplasms - pathology; Breast Neoplasms - therapy; Carcinoma, Ductal, Breast - pathology; Carcinoma, Ductal, Breast - therapy; Carcinoma, Lobular - pathology; Carcinoma, Lobular - therapy; Combined Modality Therapy; Female; Follow-Up Studies; Humans; Lymph Nodes - pathology; Lymph Nodes - radiation effects; Mastectomy, Segmental - mortality; Middle Aged; Neoadjuvant therapy; Neoadjuvant Therapy - mortality; Neoplasm Recurrence, Local - pathology; Neoplasm Recurrence, Local - therapy; Neoplasm Staging; Partial mastectomy; Radiation therapy; Radiotherapy, Adjuvant - mortality; Receptor, ErbB-2 - metabolism; Receptors, Estrogen - metabolism; Receptors, Progesterone - metabolism; Retrospective Studies; Subtype; Survival Rate; Neoadjuvant therapy; Partial mastectomy; Radiation therapy; Subtype; Breast neoplasm
• ISSN: 1526-8209; 1938-0666
• DOI: 10.1016/j.clbc.2018.08.009

Given the lack of established indications for elective nodal irradiation (ENI) in ypN0 patients after neoadjuvant chemotherapy (NAC) and breast-conserving surgery (BCS), we set out to investigate the role of ENI in ypN0 patients according to subtype and pathologic complete remission (pCR) status. We analyzed 261 patients who received NAC followed by BCS and adjuvant radiotherapy in 13 institutions of the Korean Radiation Oncology Group from 2005 to 2011. The tumors were classified into one of 3 subtypes: luminal (estrogen receptor positive or progesterone receptor positive and HER2 negative), HER2 (HER2 positive), or triple negative (estrogen receptor, progesterone receptor, and HER2 negative). We compared locoregional control (LRC), disease-free survival (DFS), and overall survival (OS) according to ENI in different subgroups generated by the subtype and pCR statuses. In all patients, the 5-year LRC, DFS, and OS rates were 96.0%, 91.0%, and 96.8%, respectively. In all patients, axillary lymph node dissection was found to be the only favorable factor for LRC (P = .023) and DFS (P = .001). Age ≥ 50 years (P = .027), negative resection margin (P = .002), and axillary lymph node dissection (P = .002) were all favorable factors for OS. ENI did not affect LRC, DFS, or OS. Subgroup analysis by tumor subtype and pCR showed that ENI was not associated with greater LRC or DFS in any subgroups. In ypN0 patients after NAC and BCS, ENI did not improve LRC or survival, regardless of subtype or primary tumor response. This result should be verified through larger prospective trials. This multi-institutional study aimed to investigate the role of elective nodal irradiation (ENI) in ypN0 patients following neoadjuvant chemotherapy and breast-conserving surgery according to subtype and primary tumor response. We analyzed 261 patients and found that ENI does not improve survival regardless of subtype or primary tumor response. Whole-breast irradiation might be sufficient in ypN0 patients.