Accurate assessment of metastasis of sentinel lymph nodes (SLNs) is important for deciding whether to remove axillary lymph nodes and providing appropriate treatment for patients. However, new diagnostic methods are required because there is a heavy workload for pathologists, and current methods have high false-negative rates and low sensitivity, and are expensive. Recently, we developed a “semi-dry dot-blot (SDB)” procedure, which visualizes the presence of cancer cells in the lavage fluid of sectioned lymph nodes by anti-pancytokeratin antibody (AE1/AE3) and chromogen on a dot-blot membrane. This method is based on the simple principle that there is usually no epithelial component in the lymph node if cancer does not develop into metastasis to the lymph node. We evaluated the validity and efficacy of the SDB method for the diagnosis of lymph node metastasis in a clinical setting.
To evaluate the efficacy of the SDB method in sentinel lymph node (SLN) biopsy, 174 SLNs from 100 cases of clinically node-negative breast cancer were analyzed. Each SLN was longitudinally sliced at 2-mm intervals and the sensitivity, specificity, accuracy, and time required for the SDB method were determined and compared with the permanent  pathology report. Metastasis was detected in 15 SLNs (8.6%), and the sensitivity, specificity, accuracy, and mean required time of the SDB method were 93.3%, 96.9%, 96.6%, and 43.3 minutes, respectively. The cost for two SLN analyses by the SDB method was approximately 10 USD, which included cutting blades, primary and secondary antibodies, chromogen, filter, absorption paper, and dot-blot membrane. Special equipment was not necessary, but a centrifuge and micropipette were required.
The SDB method is simple, accurate, cost-effective, and feasible for the intraoperative diagnosis of SLN metastasis without the loss of lymph node tissue, and it enables a simultaneous pathological investigation and application to other cancers. We plan to develop a kit product, which will contribute to cost reduction for the detection of SLN metastasis. We succeeded in making this system as a rapid test kit, which is currently on clinical trial with support of Japan Agency for Medical Research and Development. We aim for future government approval.

Thyroid follicular carcinomas are diagnosed by postoperative pathological diagnosis with views of capsule invasion, vascular invasion, or metastasis to other organ. Thus, it is difficult to diagnose preoperatively by fine-needle aspiration cytology. P53-binding protein 1 (53BP1) is one of nuclear proteins, that seems to reflect genomic instability of thyroid tumors. We already evaluated immunofluorescence analysis of 53BP1 expression in follicular carcinoma and follicular adenoma, and are trying to apply this result to the preoperative diagnosis of thyroid follicular tumors.

Superficial non-ampullary duodenal epithelial tumors (SNADETs) are duodenal adenomas and adenocarcinomas arising from non-ampullary lesions. Recently, SNADETs have received increased recognition because of improvements in endoscopic devices and increased awareness among endoscopists. However, the guidelines for SNADETs have just been published and lack strong recommendations.

In endoscopic diagnosis, we are researching the ability to detect duodenal lesions by using Linked Color Imaging (Fujifilm Co., Ltd.), which is one of the image-enhanced endoscopies. If LCI mode is confirmed to be useful, it is expected that SNADETs can be detected and diagnosed by medical examination endoscopy.

Most SNADETs remain in the mucosa without lymph node metastasis; therefore, endoscopic treatment is often the first treatment choice. However, standardized endoscopic techniques to resect SNADETs are yet to be determined. Classical endoscopic mucosal resection (CEMR), a snare excision with submucosal injection, is commonly utilized for SNADETs ＜20 mm. Although CEMR is simple and safe, the anatomical characteristics of SNADETs often result in inadequate outcomes. For example, endoscopic maneuverability is often poor given their narrow lumen with sharp curves. Indeed, the en bloc resection and R0 resection rates of CEMR for SNADETs have been reported to be 63%–89% and 33.6%–62%, respectively. Lower R0 resection rates can cause local recurrence in up to 7.7% of cases. Following the introduction to the treatment of the stomach and colon, endoscopic submucosal dissection (ESD) has been introduced for SNADETs > 20 mm, and it has high en bloc and R0 resection rates (98.6%–100% and 86%–87.8%, respectively). However, duodenal ESD is a technically challenging procedure due to the extremely high risk of complications. In particular, the reported intraoperative and delayed perforation rates are 27.0%–35.7% and 6.3%–12.5%, respectively.

Underwater endoscopic mucosal resection (UEMR) has been recently introduced as an innovative endoscopic resection technique. The chief characteristic is water submersion to fill the duodenal lumen, instead of submucosal injection. Compared with CEMR, UEMR has the following advantages: lower possibility of unintentional snare fastening of the muscularis, ease of capture of relatively large lesions due to less duodenal lumen distension, and protection of the deeper duodenal wall from electrosurgical injury. In recent years, UEMR has become more widespread as a treatment for SNADETs ＜ 20 mm. However, the reported negative horizontal margin and R0 resection rates remain moderate (46%–67%), resulting in a residual recurrence rate of 2.8%-5%.

Therefore, we designed "underwater EMR with submucosal injection and marking (UEMR-SIM) "as a modified combined method to improve the negative horizontal margin rate. UEMR-SIM has the following three underlying concepts: (i) underwater conditions for optimal snaring (the same as UEMR), (ii) marking that not only guides the lesion border in underwater conditions but also works as an anchor during snare deployment, and (iii) submucosal injection of a small volume of saline to expand the lesions and acquire additional horizontal margins.

We have started a prospective randomized controlled trial to investigate the efficacy of UEMR-SIM for SNADETs and compared with that of CEMR. If the efficacy of UEMR-SIM is proved, it is expected that a new endoscopic treatment for SNADETs will be established.

In duodenal ESD for SNADETs ＞ 20 mm, the high rate of intraoperative and delayed perforation is problem. In particular, delayed perforation can lead to severe peritonitis and retroperitonitis. In recent years, laparoscopic and endoscopic cooperative surgery (LECS) is widespread for SNADETs. Although the closure of defect to prevent delayed perforation is suggested, there have not been established method.

We are conducting research to prevent delayed perforation by transplanting an autologous myoblast sheet in collaboration with Professor Kanetaka et al. The proof of concept has already been confirmed with a large animal experiment.

From April 2021, we have started a physician-led clinical trial "prevention of delayed perforation of duodenal ESD using an autologous myoblast sheet". If the usefulness of this regenerative medicine is proved, it is expected that the safety of endoscopic treatment for SNADETs will be developed.

Thyroid oncocytoma is a rare thyroid tumor in which abnormal mitochondria, in which the electron transport chain complex I does not function due to abnormal mitochondrial DNA (mDNA), are accumulated in the cytoplasm. Since this type of tumor cell cannot produce ATP by oxidative phosphorylation in mitochondria, it is considered that ATP production depends on substrate level phosphorylation in glycolysis and TCA cycle. Therefore, thyroid oncocytoma is expected to be more susceptible to cytotoxicity due to inhibition of glycolysis and inhibition of glutamine metabolism, which is important for substrate level phosphorylation in the TCA cycle than for typical thyroid cancer. Therefore, we are conducting research to compare the susceptibility of thyroid oncocytoma to typical thyroid cancer cell lines to various metabolic inhibitors and to identify the predominant ATP production pathway in each. We are also investigating the involvement of mitochondrial function by creating a mitochondrial DNA-deficient cells (ρ0). Furthermore, we plan to investigate the combined enhancement effect of these metabolism inhibitors and conventional thyroid cancer treatment methods (radiation therapy, kinase inhibitors, etc.).

We are conducting research to clarify the role of autophagy in the thyroid gland and whether autophagy suppresses or promotes carcinogenesis when thyroid exposed to external radiation. Specifically, we are observing changes in autophagy when growth stimulation / suppression is given to normal thyroid gland, and investigating thyroid function at promotion / suppression of drug-induced autophagy. Furthermore, by observing Atg5TPO-KO mice for a long period of time, we are investigating whether autophagy deficiency influences thyroid function and morphological changes, as well as the frequency of carcinogenesis due to irradiation and the involvement of ROS production.