Sentinel lymph node biopsy in women with pT1a or “microinvasive” breast cancer

Abstract

The role of sentinel lymph node biopsy (SLNB) in pT1a and "microinvasive" breast cancer has not been extensively studied. We report our experience with SLNB in patients with "minimal" breast cancer to determine the incidence and type of SLN metastases, and to study the potential impact on their surgical or oncological management. Among some 3387 women operated upon for primary breast cancer who underwent sentinel lymph node biopsy at nine institutions participating in the Rome Breast Cancer Study Group, 251 were staged pT1a or pT1mic (7.4%). There were 13 cases of sentinel lymph node metastases identified in this group of patients (5.2%), seven macrometastases and six micrometastases. Additionally, ITC were diagnosed by immunohistochemistry in four cases (1.6%). The incidence of SLN metastases was 7/174 (4%) and 6/77 (7.8%) in patients with pT1a and pT1mic tumors, respectively (p=0.2). Age and histological grade were predictive factors for SLN metastases. Chemotherapy was seldom directed by axillary node status (8/38 patients). As the incidence of SLN metastases in these patients is very small, particularly in the pT1a group, the indications for even a minimally invasive procedure, such as sentinel lymph node biopsy, should be probably individualized.

Re-evaluating the role of sentinel lymph node biopsy in microinvasive breast carcinoma

“…Authors reporting a high incidence of positive sentinel lymph nodes argue in favor of sentinel lymph node biopsy in all patients with microinvasive carcinoma, 9,19,28,30,31 whereas authors reporting the low incidence of positive sentinel lymph nodes have questioned whether sentinel lymph node biopsy should be performed in all such patients. 32,[34][35][36][37][38] The wide variation in reported incidence can be explained in part by the diversity in the histopathologic definition of microinvasive carcinoma used in various reports. In 1982, Lagios et al, 40 Later, the 5th edition of the AJCC staging manual defined microinvasive carcinoma as extension of carcinoma cells beyond basement membrane with no single focus 41 mm, whereas Silver and Tavassoli 11 defined it as a single focus of invasive carcinoma p2 mm or up to three foci of invasion, each p1 mm in greatest dimension.…”

Microinvasive breast cancer: pathological parameters, cancer subtypes distribution, and correlation with axillary lymph nodes invasion. Results of a large single-institution series

“…In the study of the Rome Breast Cancer Study Group [21], cited in the meta-analysis, incidence of SLN metastases was 4 % in pT1a tumors and 7.8 % in pT1mic. Authors speculate that this might reflect a more aggressive nature of this subgroup, from the very beginning, as previously reported in another publication [22].…”

The Demographic Features, Clinicopathological Characteristics and Cancer-specific Outcomes for Patients with Microinvasive Breast Cancer: A SEER Database Analysis

“…In our multivariate analysis, lymph node metastasis was an independent prognostic factor for worse CSS ( P < 0.001) and OS ( P ≤ 0.010). The incidence of pathologically positive axillary lymph node metastases for patients with microinvasive ductal carcinoma of the breast has been reported as 0–20% 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 . Maibenco et al .…”