Screening, monitoring, and diagnosis are critical in oncology treatment. However, there are limitations with the current clinical methods, notably the time, cost, and special facilities required for radioisotope-based methods. An alternative approach, which uses magnetic beads, offers faster analyses with safer materials over a wide range of oncological applications. Magnetic beads have been used to detect extracellular vesicles (EVs) in the serum of pancreatic cancer patients with statistically different EV levels in preoperative, postoperative, and negative control samples. By incorporating fluorescence, magnetic beads have been used to quantitatively measure prostate-specific antigen (PSA), a prostate cancer biomarker, which is sensitive enough even at levels found in healthy patients. Immunostaining has also been incorporated with magnetic beads and compared with conventional immunohistochemical methods to detect lesions; the results suggest that immunostained magnetic beads could be used for pathological diagnosis during surgery. Furthermore, magnetic nanoparticles, such as superparamagnetic iron oxide nanoparticles (SPIONs), can detect sentinel lymph nodes in breast cancer in a clinical setting, as well as those in gallbladder cancer in animal models, in a surgery-applicable timeframe. Ultimately, recent research into the applications of magnetic beads in oncology suggests that the screening, monitoring, and diagnosis of cancers could be improved and made more accessible through the adoption of this technology.

The effects of raloxifene, a novel selective estrogen receptor modulator, were studied in a mouse metastatic mammary cancer model expressing cytoplasmic ERα.

Accurate pre-operative localization of nonpalpable lesions plays a pivotal role in guiding breast-conserving surgery (BCS). In this multicenter feasibility study, nonpalpable breast lesions were localized using a handheld magnetic probe (TAKUMI) and a magnetic marker (Guiding-Marker System^®). The magnetic marker was preoperatively placed within the target lesion under ultrasound or stereo-guidance. Additionally, a dye was injected subcutaneously to indicate the extent of the tumor excision. Surgeons checked for the marker within the lesion using a magnetic probe. The magnetic probe could detect the guiding marker and accurately localize the target lesion intraoperatively. All patients with breast cancer underwent wide excision with a safety margin of ≥5 mm. The presence of the guiding-marker within the resected specimen was the primary outcome and the pathological margin status and re-excision rate were the secondary outcomes. Eighty-seven patients with nonpalpable lesions who underwent BCS, from January to March of 2019 and from January to July of 2020, were recruited. The magnetic marker was detected in all resected specimens. The surgical margin was positive only in 5/82 (6.1%) patients; these patients underwent re-excision. This feasibility study demonstrated that the magnetic guiding localization system is useful for the detection and excision of nonpalpable breast lesions.

An experimental apparatus for three-dimensional sensitivity mapping of a handheld magnetic probe with a permanent magnet and a Hall sensor was developed. To optimize the shapes and sizes of the magnets, the sensitivity mappings of two types of magnets, column- and cone-type magnets, were evaluated by the experimental apparatus. The longitudinal sensitivities of column and cone types are 8 and 9 mm, respectively, for 5 μL of magnetic nanoparticles. The measured longitudinal sensitivities agree well with the sensitivities calculated by the finite element method. Furthermore, the maximum lateral resolutions of column and cone types are 4.1 and 3.7 mm, respectively. In terms of the directionality, the sensitivities of column and cone types of the angle of 90° with respect to the probe axis fall approximately to 72% and 50% at 6 mm distance from the probe head, indicating that the cone type has high directionality due to its sharp shape. The measurement of sensitivity mapping revealed that the characteristics of the cone-type magnet are superior to that of the column-type magnet for the identification of sentinel lymph nodes.

The magnetic technique, consisting of a magnetic tracer and a handheld magnetometer, is a promising alternative technique for sentinel lymph node dissection (SLND) and was shown to be non-inferior to the standard technique in terms of identification rates. In this study, injection characteristics (iron dose, dilution, time course and massaging) were evaluated to optimize magnetic tracer uptake in the sentinel lymph nodes (SLN) in a rat hindleg model. 202 successful SLNDs were performed. Iron uptake in the SLN is proportional (10% utilization rate) to the injection dose between 20 and 200 μg, showing a plateau uptake of 80 μg in the SLN around 1000 μg injection. Linear regression showed that time had a higher impact than dilution, on the SLN iron uptake. Massaging showed no significant change in iron uptake. The amount of residual iron at the injection site was also proportional to the injection dose without any plateau. Time was a significant factor for wash-out of residual iron. From these results, preoperative injection may be advantageous for SLN detection as well as reduction in residual iron at the injection site by potential decrease in required injection dose.

We have developed the magnetic probe with a diamond quantum sensor and electromagnetic coils to detect sentinel lymph nodes (SLNs), as the medical application of diamond quantum sensing. The probe magnetizes magnetic nanoparticles (MNPs) accumulated in SLNs and detect the magnetic fields of magnetized MNPs. In this study. We designed a ferromagnetic core that has a unique shape and optimized the magnetic field generation system for improving the detection performance, such as the magnetic sensitivity and detectable distance. The proposed magnetic core enhances an excitation magnetic field strength at a longer distance and suppresses a bias field strength at a location of the diamond quantum sensor. The increment of the excitation field is approximately 370% and the decrement of the bias field is approximately 45%. In addition to the proposed magnetic core, even applying a cancellation coil, the excitation field strength is ten-fold compared with the coil only structure, suggesting the larger magnetization of MNPs generates the large magnetic field for longer detectable distance.