Axillary sentinel node identification in breast cancer patients: degree of radioactivity present at biopsy is critical

Summary Background: The radioactivity present in the patient (Actrem) at sentinel node (SN) biopsy will depend on injected activity amount as well as on the time interval from tracer injection to biopsy, which both show great variations in the literature. The purpose of this study was to analyse the influence of varying Actrem levels on the outcome of axillary SN biopsy in patients with breast cancer (BC). Material and methods: Eight hundred and fifty‐eight patients with BC were consecutively referred to SN biopsy, 21% for a same‐day and 79% of the patients for a 2‐day procedure. Four hundred and nineteen patients underwent scintigraphy and 439 did not. For same‐day procedures, 50 MBq 99mTc‐nanocolloid (Nanocoll®) was injected, and for 2‐day procedures 110 MBq. For the analysis of SN biopsy outcome, the patients were divided into three Actrem groups: 20 MBq (21%). During surgery, SNs were located using a hand‐held gamma probe supported by image information when available and blue dye injection. Pathology included haematoxylin–eosin staining followed by immunohistochemistry. Results: The number of SNs removed (mean value 1·87 versus 2·14, P = 0·0003) and the probability of finding a malignant SN (P = 0·034) were lower in the 20 MBq. Of the 25 patients with SN non‐detection, 20 patients had an Actrem