Sentinel lymph node identification with magnetic nanoparticles

Most solid malignancies have a tendency to spread through the lymphatic system to locoregional lymph nodes. Presence of metastasis is an important prognostic factor, and is used to determine the optimal treatment of the patient. The sentinel lymph nodes (SLNs) receive direct lymphatic drainage from the tumour area, and are therefore most likely the first site of metastasis, if present. The SLNs therefore play a crucial role in the staging and treatment of cancer. This thesis describes the use of magnetic nanoparticles for SLN identification in colorectal- and breast cancer. In colorectal cancer currently used experimental techniques suffer from limitations, hampering widespread clinical implementation of the technique. In breast cancer, a radioactive tracer is used. However, the worldwide availability of radioisotopes, and therefore the best treatment, is limited. The aim of the research in this thesis is twofold. In colorectal cancer, the objective is to introduce a SLN procedure allowing to improve nodal staging accuracy in a routine clinical workflow after ex vivo administration of magnetic nanoparticles. In breast cancer, we aim to introduce an entirely radioisotope-free method for in vivo SLN Biopsy (SLNB). A commercially available magnetometer and magnetic tracer were used for SLN identification in patients suffering from colorectal cancer to evaluate the feasibility of the technique. Patient, animal and phantom studies were performed to optimize the use of the SLNB technique with magnetic nanoparticles in breast cancer patients. With the work in this thesis we have established the feasibility of using ex vivo magnetic SLNM to improve staging accuracy of colorectal cancer patients, in routine clinical practice. Furthermore, by analysing and resolving shortcomings and pitfalls of the existing intraoperative magnetic technique for SLNB our research made important contributions to make the introduction of an entirely radioisotope-free technique for SLNB in breast cancer patients possible.