Abstract
PurposeSentinel lymph node biopsy (SLNB) was introduced as a minimally invasive technique for nodal staging. Since associated morbidity is not negligible, it is highly relevant to pursue a more minimally invasive alternative. The purpose of this study was to prospectively evaluate the sensitivity of fine needle aspiration cytology (FNAC) with combined gamma probe and ultrasound (US) guidance in comparison with the gold standard histology of the sentinel node (SN) after SLNB for detecting metastasis.MethodsThe study was designed as a prospective, multicentre, open-label, single-arm trial enrolling patients with newly diagnosed cutaneous melanoma or breast cancer between May 2015 and August 2017. Sample radioactivity was measured using a Mini 900 scintillation monitor. After FNAC, all patients underwent SLNB. Sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) were estimated.ResultsAccrual was terminated early following an unplanned interim analysis indicating that a FNAC sensitivity of at least 80% could not be achieved. In total 58 patients of the originally planned 116 patients underwent FNAC with gamma probe and US guidance. There were no true-positive FNAC results, 14 false-negative results and one false-positive result, and thus the sensitivity, specificity, PPV and NPV of FNAC were 0%, 98%, 0% and 75%, respectively. At least 75% of the FNAC samples had a radioactivity signal higher than the background signal.ConclusionFNAC with gamma probe and US guidance is not able to correctly detect metastases in the SN and is therefore not able to replace SLNB. Gamma probe-guided US is a highly accurate method for correctly identifying the SN, which offers possibilities for future research.
Highlights
The sentinel lymph node biopsy (SLNB) procedure was introduced in the early 1990s as a less-invasive technique than elective lymph node dissection, enabling selective detection and histopathological inspection of the primary draining lymph node in the regional lymph node basin related to the primary tumour site, e.g. melanoma or breast cancer [1, 2]
In patients with insufficient cytology Fine needle aspiration cytology (FNAC) was recorded as negative. One of these patients turned out to have a positive sentinel node (SN) on histology, and the FNAC result was recorded as false-negative
A positive SN on histology after SLNB was found in 14 patients (24.1%), 10 with melanoma and 4 with breast cancer
Summary
The sentinel lymph node biopsy (SLNB) procedure was introduced in the early 1990s as a less-invasive technique than elective lymph node dissection, enabling selective detection and histopathological inspection of the primary draining lymph node in the regional lymph node basin related to the primary tumour site, e.g. melanoma or breast cancer [1, 2]. Less invasive than elective lymph node dissection, the morbidity associated with SLNB is not negligible This is of particular concern since a positive sentinel node (SN) is found in only 20–30% of patients [5,6,7]. Several studies have focused on US examination with or without FNAC in melanoma patients, but sensitivity rates vary greatly and most studies lacked a method to accurately identify the SN prior to US examination and FNAC [12]. This problem could be overcome by using a hand-held gamma probe as an aid to US identification of the SN after lymphoscintigraphy. This has been shown to be feasible in several studies in breast cancer patients, in which the SN was correctly identified in 75–100% of patients [13,14,15,16]
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