The use of blue dye alone for sentinel lymph node biopsy after neoadjuvant chemotherapy in patients with initially node-positive breast cancer

INTRODUCTION

False-negative sentinel lymph node biopsy (SLNB) rates following neoadjuvant chemotherapy (NACT) in initially node-positive (cN1/2) breast cancer patients are high, but decrease when lymph nodes are clipped, ≥3 sentinel lymph nodes (SLN) are removed or dual-tracer localization (radioisotope and blue dye) is used. Radiotracer, however, is often unavailable and outcomes with blue dye alone are unknown.

MATERIALS AND METHODS

Initially cT1-4, cN1/2 patients treated with NACT in 2013-2023 who underwent SLNB using blue dye alone were evaluated regarding SLN identification, axillary recurrence, disease-free and overall survival rates.

RESULTS

Of 119 patients included, 19 remained cN1/2 after NACT. SLNB was performed using blue dye alone in 100 ycN0 cases (84%), with an identification rate of 96%. The SLN was negative in 70/119 cases (i.e. 59% avoided axillary dissection). The number of SLN detected was ≥3 in 55/70 cases (78%) (median 3.1; 1-6). Median age was 49 years (25-84). Most were T2 (n = 40, 57.1%), N1 (n = 64, 91.4%). Predominant subtypes were ERBB2 (52.9%) and triple-negative (20%). No axillary recurrence occurred over a median 36-month period. Five-year disease-free and overall survival were, respectively, 85.9% (95%CI: 74-99.8) and 96.3% (95%CI: 89.4-100). The ERBB2 subtype (1.99, 95%CI: 1.02-3.85, p = 0.04) and N1 lymph node status (2.58, 95%CI: 1.54-9.10, p = 0.03) were associated with a greater likelihood of undergoing SLNB alone without axillary dissection.

CONCLUSIONS

SLNB with blue dye alone following NACT in initially cN1/2 patients avoided axillary dissection in almost 60% of cases, with no recurrences during the period evaluated. Longer follow-up studies are necessary.

Reaching task performance is associated to neuromuscular junction adaptations in rats with induced diabetes mellitus

Upper limb performance is affected by diabetes mellitus (DM). Neuromuscular junction (NMJ) is a key structure to understand the relationship between performance and morphology in DM. The aim of the study was to analyze NMJ plasticity due to DM in an animal model and its relationship with the function of forelimbs in rats. Twelve Wistar rats were divided into control (C) and DM groups. Animals were trained to perform a grasping task, following procedures of habituation, shaping, and reaching task. DM was induced using streptozotocin. Forelimb neuromuscular performance for dexterity was evaluated one day before DM induction and five weeks following induction. After that, biceps, triceps, and finger flexors and extensors were removed. Connective tissue and muscle fiber cross-sectional area (CSA) were measured. NMJ was assessed by its morphometric characteristics (area, perimeter, and maximum diameter), using ImageJ software. Motor performance analyses were made using single pellet retrieval task performance test. Student’s t-test was used for comparisons between groups. A significant decrease in all NMJ morphometric parameters was observed in the DM group compared with the C group. Results showed that DM generated NMJ retraction in muscles involved in a reaching task. These alterations are related to signs of muscular atrophy and to poor reaching task performance. In conclusion, induced DM caused NMJ retraction and muscular atrophy in muscles involved in reaching task performance. Induced DM caused significantly lower motor performance, especially in the final moments of evaluation, when DM compromised the tropism of the muscular tissue.