Low incidence of lymph node metastasis in patients with microinvasive breast cancer: a Korean nationwide study

Abstract

Purpose Microinvasive breast cancer (MIBC) is an invasive carcinoma with a tumor dimension not exceeding 1 mm. Owing to its low incidence, the rate of axillary node metastasis and its management are not well established. The aim of this study was to assess the incidence of lymph node metastasis (LNM) and identify variables associated with LNM, as well as to evaluate the need for axillary staging in MIBC patients by analyzing nationwide data. Methods The Korean Breast Cancer Society registry was searched to identify MIBC patients diagnosed between January 1996 and April 2020. Patients without neoadjuvant chemotherapy experiences, systemic metastasis, and missing or discordant data were eligible for the analysis. The incidence rate of LNM was determined, and variables associated with LNM were identified by multivariable regression analysis. Results Of 2,427 MIBC patients identified, 98 (4.0%) had LNM and 12 (0.5%) had N2/3 disease. Type of breast operation (odds ratio [OR], 2.093; 95% confidence interval [CI], 1.332–3.290; P = 0.001), age (OR, 2.091; 95% CI, 1.326–3.298; P = 0.002), hormone receptor status (OR, 2.220; 95% CI, 1.372–3.594; P = 0.001), and lymphovascular invasion (OR, 11.143; 95% CI, 6.354–19.540; P < 0.001) were significantly related to LNM. Conclusion The incidence of LNM in MIBC patients was only 4.0% in our study, suggesting that de-escalation of axillary surgical interventions could be carefully considered. The indications for axillary staging should be individualized considering tumor volume, age, hormone receptor status, and lymphovascular invasion to improve the quality of life of MIBC survivors.

Characteristics and risk factors of axillary lymph node metastasis of microinvasive breast cancer

“…In an observational retrospective study of prospectively collected data from 10 Italian Breast Centers, LVI was the only statistically signi cant variable associated with the lymph node status [3]. In a national database study carried out by the Korean Breast Cancer Society, LVI was the strongest risk factor among multiple variables affecting ALNM (OR = 11.143; 95% CI: 6.354-19.540; p < 0.001) [11], which correspond with the present study ndings. Lymphovascular invasion was detected in only 2.3% of overall patients with MIBC in the present study, while 27.8% and 1.7% of those with positive and negative lymph nodes had LVI, respectively.…”

“…From previous literature reviews involving patients with American Joint Committee of Cancer-de ned MIBC who had undergone SLNB [6,7,17,18], we evaluated the most recent studies reporting the number of patients with axillary metastasis and associated risk factors (Table 4). The ALNM rate ranged from 4.0% to 21.5% in the studies published between 2011 and 2022 [3,7,10,11,[14][15][16][19][20][21]. The signi cant variation observed could be attributed to the different pathological methods used to examine the sentinel node and the methodology used to section the breast tissue [7].…”

“…A common risk factor for ALNM was LVI. Lymphovascular invasion was associated with sentinel lymph node (SLN) positivity in a univariate and/or multivariate analysis of several studies, including single center, multicenter, or national database studies [3,11,15,17,19,28]. In an observational retrospective study of prospectively collected data from 10 Italian Breast Centers, LVI was the only statistically signi cant variable associated with the lymph node status [3].…”

“…Performing axillary staging for the risk assessment of MIBC is advised in previous studies [9]. While the rate of axillary lymph node metastasis (ALNM) varies greatly, ranging from 4-20%, it remains an adverse prognostic factor [7,10,11]. In a study involving 11,692 patients whose data were derived from the Surveillance Epidemiology and End Results (SEER) database, lymph node metastasis demonstrated a signi cant prognostic impact on breast cancer-speci c survival.…”

“…The decision of performing axillary staging can burden the patients with re-operation if it has not been performed at the initial surgery. To predict ALNM, previous studies have identi ed various risk factors for sentinel lymph node positivity, with young age and lymphovascular invasion (LVI) being the most common and well-proven factors [3,7,10,11,[14][15][16]. However, due to the small proportion of cases attributed to MIBC among all breast cancer cases, and even smaller proportion of patients with MIBC who develop lymph node metastasis, large-scale studies with homogeneity are lacking.…”