Lymph node status after sentinel node biopsy followed by axillary lymph node dissection among breast cancer patients: a population-based study

Abstract

Background: Axillary lymph node dissection (ALND) for breast cancer patients is performed if there are metastases in sentinel nodes (SNs). However, ALND does not seem to provide a therapeutic benefit for breast cancer patients with few involved SNs and the current literature indicates that patients with <3 positive SNs are overtreated if ALND is performed. Luminal A-like tumors are recommended chemotherapy if ≥4 lymph node metastases (LNMs) are present. The extent to which patients with luminal A-like tumors with ≥4 LNMs could be potentially undertreated with adjuvant chemotherapy if the indication for ALND is set to >2 positive SNs is unclear. Aim: To quantify the group of luminal A patients with ≥4 LNMs who risk being undertreated with adjuvant chemotherapy and to investigate if the ratio between positive SNs and the total amount of examined SNs can provide additional information of the axillary tumor burden. Material and methods: Patients in Region Västra Götaland with clinically node-negative breast cancer who had undergone sentinel node biopsy (SNB) followed by ALND were analyzed and the SNB findings were compared to the results from the ALND. The potentially undertreated luminal A group was quantified. The ratio of positive to total SNs and its ability to describe the axillary tumor burden was evaluated using Pearson’s chi-square test. Results and conclusion: 16 (17.6%) of the 91 patients with luminal A-like tumors had ≥4 LNMs and 2 of these had >2 positive SNs leaving 14 patients (15.4%) with <3 positive SNs and ≥4 LNMs. The ratio of positive SNs to the total amount of SNs examined was significant in a multivariable analysis for predicting ≥4 LNMs among luminal A-like patients (p=0.027). This was also true for all subtypes combined (p<0.001). Our results indicate that about one sixth of patients with luminal A-like tumors may be undertreated with adjuvant chemotherapy due to a falsely low axillary staging if the indication for ALND is set to >2 positive SN. The SN ratio could be effective at identifying many of these patients.