Impact of omission of completion axillary lymph node dissection (cALND) or axillary radiotherapy (ax RT) in breast cancer patients with micrometastases (pN1mi) or isolated tumor cells (pN0[i+]) in the sentinel lymph node (SN): Results from the MIRROR study

Abstract

CRA506 Background: The Dutch MIRROR study is the largest cohort study on pN1mi and pN0(i+) in the SN era with long-term follow-up, central pathology review (6th AJCC-classification), and separate analyses on the use of adjuvant systemic therapy (AST). In patients not receiving AST, pN1mi and pN0(i+) as final N-stage were shown to be independent prognosticators for disease-free survival (SABCS 2008, #23, oral). As a substantial number of patients in the MIRROR study did not undergo cALND or ax RT, we questioned whether this policy was safe in patients with pN1mi(sn) or pN0(i+)(sn). Methods: Patients operated for breast cancer in all Dutch hospitals in the years 1998–2005, having favorable primary tumor characteristics, and having undergone an SN biopsy without macrometastases as final N-stage were included. For this present research question, patients were categorized by their SN-stage. Median follow-up was 4.7 years. The Kaplan-Meier method was used to estimate 5-year axillary recurrence (AR) rates, and Cox regression was used to estimate the hazard ratios (HR). In the analyses, the effect of AST was taken into account. Results: In total, 835 patients with pN0(i-)(sn), 799 patients with pN0(i+)(sn), and 958 patients with pN1mi(sn) were included. AR rates, and HRs on AR are displayed below. Conclusions: Omission of cALND or ax RT in patients with pN1mi(sn) resulted in a significantly higher 5-year AR rate, even after correction for AST, and other patient and tumor characteristics. This indicates that patients with pN1mi(sn) should undergo cALND or ax RT to prevent AR. Support: The Netherlands Organization for Health Research and Development (ZonMw) and the Dutch Breast Cancer Trialists’ Group (BOOG). [Table: see text] No significant financial relationships to disclose.

Sentinel Lymph Node Biopsy in Breast Cancer: Predictors of Axillary and Non-Sentinel Lymph Node Involvement

“…As reported in the previous studies, the low identification rate of micrometastases by frozen section and conventional H&E staining (7) and the strong evidence about the impact of micrometastatic nodal disease on locoregional recurrence (31,32) warrant identification of primary tumour-related histopathological factors with high predictive ability. Many studies have validated the MSKCC nomogram, which was proposed for predicting non-SLN metastases.…”

Radiation field design and regional control in sentinel lymph node‐positive breast cancer patients with omission of axillary dissection

“…Invasive lobular 4 (13) 21 (13) 13 (20) 6 (15) 5 (25) Select studies of patients with positive SLN and who did not undergo ALND have demonstrated low regional recurrence rates in the setting of adjuvant systemic therapy and RT (Table 5). 1,[5][6][7][8][9][10][11][12][13][14]28 Those series differed with respect to the length of median follow-up, the definition of a positive SLN, reasons for omitting ALND, and the receipt of systemic therapy. Although several of those reports 1,5,7,11 described the RT fields used, none reported treatment outcomes stratified by RT field design.…”

Sentinel Lymph Node Biopsy in Early Breast Cancer

“…Omission of any axillary treatment resulted in a higher 5-year recurrence rate in pN1(mi) but not in pN0(i+) patients (5% vs. 1%, hazard ratio (HR) 4.39) [28], even after correction for adjuvant systemic treatment.…”