Tumor Contact With Internal Mammary Perforator Vessels as Risk Factor for Gross Internal Mammary Lymph Node Involvement in Patients With Breast Cancer

Sophie T Behzadi; Rebecca Moser; Sophia Kiesl; Jana Nano; Jan C Peeken; Julius C Fischer; Eva M Fallenberg; Thomas Huber; Bernhard Haller; Evelyn Klein; Marion Kiechle; Stephanie E Combs; Kai J Borm

doi:10.1016/j.ijrobp.2024.02.030

Tumor Contact With Internal Mammary Perforator Vessels as Risk Factor for Gross Internal Mammary Lymph Node Involvement in Patients With Breast Cancer

Int J Radiat Oncol Biol Phys. 2024 Mar 7:S0360-3016(24)00339-0. doi: 10.1016/j.ijrobp.2024.02.030. Online ahead of print.

Authors

Affiliations

¹ Department of Radiation Oncology, TUM School of Medicine and Health, Technical University Munich (TUM), Klinikum rechts der Isar, Munich, Germany.
² Department of Radiology, TUM School of Medicine and Health, Technical University Munich (TUM), Klinikum rechts der Isar, Munich, Germany.
³ Institute of AI and Informatics in Medicine, TUM School of Medicine and Health, Technical University Munich (TUM), Klinikum rechts der Isar, Munich, Germany.
⁴ Department of Gynecology and Obstetrics, TUM School of Medicine and Health, Technical University Munich (TUM), Klinikum rechts der Isar, Munich, Germany.
⁵ Department of Radiation Oncology, TUM School of Medicine and Health, Technical University Munich (TUM), Klinikum rechts der Isar, Munich, Germany; Deutsches Konsortium für translationale Krebsforschung (DKTK) - Partner Site Munich, Munich, Germany; Institute of Radiation Medicine, Helmholtz Zentrum München, Munich, Germany.
⁶ Department of Radiation Oncology, TUM School of Medicine and Health, Technical University Munich (TUM), Klinikum rechts der Isar, Munich, Germany. Electronic address: kai.borm@mri.tum.de.

PMID: 38458496
DOI: 10.1016/j.ijrobp.2024.02.030

Abstract

Purpose: The identification of internal mammary lymph node metastases and the assessment of associated risk factors are crucial for adjuvant regional lymph node irradiation in patients with breast cancer. The current study aims to investigate whether tumor contact with internal mammary perforator vessels is associated with gross internal mammary lymph node involvement.

Methods and materials: We included 297 patients with primary breast cancer and gross internal mammary (IMN+) and/or axillary metastases as well as 230 patients without lymph node metastases. Based on pretreatment dynamic contrast-enhanced magnetic resonance imaging, we assessed contact of the tumor with the internal mammary perforating vessels (IMPV).

Results: A total of 59 patients had ipsilateral IMN+ (iIMN+), 10 patients had contralateral IMN+ (cIMN+), and 228 patients had ipsilateral axillary metastases without IMN; 230 patients had node-negative breast cancer. In patients with iIMN+, 100% of tumors had contact with ipsilateral IMPV, with 94.9% (n = 56) classified as major contact. In iIMN- patients, major IMPV contact was observed in only 25.3% (n = 116), and 36.2% (n = 166) had no IMPV contact at all. Receiver operating characteristic analysis revealed that "major IMPV contact" was more accurate in predicting iIMN+ (area under the curve, 0.85) compared with a multivariate model combining grade of differentiation, tumor site, size, and molecular subtype (area under the curve, 0.65). Strikingly, among patients with cIMN+, 100% of tumors had contact with a crossing contralateral IMPV, whereas in cIMN- patients, IMPVs to the contralateral side were observed in only 53.4% (iIMN+) and 24.8% (iIMN-), respectively.

Conclusions: Tumor contact with the IMPV is highly associated with risk of gross IMN involvement. Further studies are warranted to investigate whether this identified risk factor is also associated with microscopic IMN involvement and whether it can assist in the selection of patients with breast cancer for irradiation of the internal mammary lymph nodes.