Sentinel lymph node identification using superparamagnetic iron oxide particles versus radioisotope: The French Sentimag feasibility trial

Meta-analysis of sentinel lymph node biopsy in breast cancer using the magnetic technique

BACKGROUND

The standard for sentinel lymph node biopsy (SLNB), the dual technique (radiolabelled tracer and blue dye), has several drawbacks. A novel magnetic technique without these drawbacks has been evaluated in a number of clinical trials. It uses a magnetic tracer and a handheld magnetometer to identify and excise sentinel lymph nodes. A systematic review and meta-analysis was performed to assess the performance and utility of the magnetic in comparison to the standard technique.

METHODS

MEDLINE, PubMed, Embase and the Cochrane online literature databases were used to identify all original articles evaluating the magnetic technique for SLNB published up to April 2016. Studies were included if they were prospectively conducted clinical trials comparing the magnetic with the standard technique for SLNB in patients with breast cancer.

RESULTS

Seven studies were included. The magnetic technique was non-inferior to the standard technique (z = 3·87, P < 0·001), at a 2 per cent non-inferiority margin. The mean identification rates for the standard and magnetic techniques were 96·8 (range 94·2-99·0) and 97·1 (94·4-98·0) per cent respectively (risk difference (RD) 0·00, 95 per cent c.i. -0·01 to 0·01; P = 0·690). The total lymph node retrieval was significantly higher with the magnetic compared with the standard technique: 2113 (1·9 per patient) versus 2000 (1·8 per patient) (RD 0·05, 0·03 to 0·06; P = 0·003). False-negative rates were 10·9 (range 6-22) per cent for the standard technique and 8·4 (2-22) per cent for the magnetic technique (RD 0·03, 0·00 to 0·06; P = 0·551). The mean discordance rate was 3·9 (range 1·7-6·9) per cent.

CONCLUSION

The magnetic technique for SLNB is non-inferior to the standard technique, with a high identification rate but with a significantly higher lymph node retrieval rate.

The Nordic SentiMag trial: a comparison of super paramagnetic iron oxide (SPIO) nanoparticles versus Tc(99) and patent blue in the detection of sentinel node (SN) in patients with breast cancer and a meta-analysis of earlier studies

The aim of the study is to compare the efficacy of SPIO as a tracer in sentinel node biopsy (SNB) in breast cancer with Tc and patent blue in a multicentre prospective study and perform a meta-analysis of all published studies. It also aims to follow skin discoloration after SPIO injection and describe when and how it resolves. Totally 206 patients with early breast cancer were recruited. Tc and patent blue were administered in standard fashion. Patients were injected with SPIO (Sienna+) preoperatively. SNB was performed and detection rates were recorded for both methods. Skin discoloration was followed and documented postoperatively. Data extraction and subsequent meta-analysis of all previous studies were also performed. SN detection rates were similar between standard technique succeeded and SPIO both per patient (97.1 vs. 97.6 %, p = 0.76) as well as per node (91.3 vs. 93.3 %, p = 0.34), something which was not affected by the presence of malignancy. Concordance rates were also consistently high (98.0 % per patient and 95.9 % per node). Discoloring was present in 35.5 % of patients postoperatively, almost exclusively in breast conservation. It fades slowly and is still detectable in 8.6 % of patients after 15 months. Meta-analysis depicted similar detection rates (p = 0.71) and concordance rates (p = 0.82) per patient. However, it seems that SPIO is characterized by higher nodal retrieval (p < 0.001). SPIO is an effective method for the detection of SN in patients with breast cancer. It is comparable to the standard technique and seems to simplify logistics. Potential skin discoloration is something of consideration in patients planned for breast conservation.