EVG-Based Periarterial/Perivenous Invasion (periA/V) as a High-Sensitivity Surrogate Marker for Lymph Node Metastasis in pT1 Invasive Breast Carcinoma of No Special Type.

内容摘要

Conventional assessments of lymphatic invasion in the primary tumor may fail to identify lymph node metastasis (LNM) in breast cancer. We evaluated periarterial or perivenous invasion (periA/V), using Elastica-van Gieson (EVG)-stained sections, as a histological marker associated with LNM in invasive breast carcinoma of no special type (IBC-NST), focusing on the impact of invasive tumor size. We retrospectively analyzed 213 IBC-NST cases. PeriA/V was defined as tumor nests in direct contact with perivascular elastic fibers on EVG-stained sections. Diagnostic performance was compared with that of conventional LI markers (hematoxylin and eosin and D2-40), with stratified analyses by pathological T category (pT1 vs. pT2-4) and pT1 subcategories (pT1a, pT1b, and pT1c). LNM was observed in 87 cases (40.8%). Overall, periA/V demonstrated high sensitivity (97.7%) and negative predictive value (NPV; 93.5%). In pT1 tumors (n = 130), periA/V achieved 100% sensitivity and 100% NPV (27/27), and was consistently present in all node-positive pT1b-c tumors. In multivariate analyses, periA/V remained independently associated with LNM in the pT1 group (odds ratio [OR]: 16.08, p = 0.003) and pT1c subgroup (OR: 14.7, p = 0.010). In pT2-4 tumors, periA/V became frequent regardless of nodal status, indicating reduced discriminatory value. In this exploratory single-center cohort, EVG-based periA/V demonstrated high sensitivity for LNM in pT1 IBC-NSTs, with periA/V negativity consistently observed among node-negative cases. These preliminary findings suggest that periA/V may potentially contribute to LNM risk assessment in early-stage breast cancer.