Novel surgical approach based on the sentinel node concept in patients with early gastric cancer

Efficacy of lymph node dissection for duodenal cancer according to the lymph node station

Background

Lymph node metastasis (LNM) is associated with poor prognosis in patients with duodenal cancer (DC). However, the efficacy and optimal extent of lymph node (LN) dissection have not been thoroughly discussed.

Methods

A total of 98 consecutive patients with DC who underwent surgical resection (pancreatoduodenectomy, n = 55; partial resection, n = 32; pancreas-sparing total duodenectomy, n = 9) were retrospectively analyzed. The LN stations located upstream of the lymphatic flow were defined as Np stations according to tumor location, whereas the others were defined as Nd stations. The association between the dissection of each LN station and survival outcome was investigated using the efficacy index (EI; percentage of metastases to lymph nodes in each station multiplied by the 5-year survival rate of metastatic cases).

Results

The survival of patients with LNM at the Nd stations (n = 6) was significantly worse than that of patients with LNM only at the Np stations (n = 20) (relapse-free survival, median survival time [MST], 6.0 vs. 48.4 months, p < 0.001; overall survival, MST, 15.1 vs. 96.0 months, p < 0.001). Multivariate analysis identified LNM at Nd stations as an independent prognostic factor for overall survival (hazard ratio 9.92; p = 0.015). The Np stations had a high EI (range, 8.34-20.88), whereas the Nd stations had an EI of 0, regardless of the tumor location.

Conclusions

LN dissection of the Np stations contributed to acceptable survival, whereas LNM of the Nd stations led to poor survival, possibly reflecting advanced tumor progression to systemic disease in patients with DC.

The Use of Deep Learning-Based Computer Diagnostic Algorithm for Detection of Lymph Node Metastases of Gastric Adenocarcinoma

Objectives. The diversifying modalities of treatment for gastric cancer raise urgent demands for the rapid and precise diagnosis of metastases in regional lymph nodes, thereby significantly impact the workload of pathologists. Meanwhile, the recent advent of whole-slide scanners and deep-learning techniques have enabled the computer-assisted analysis of histopathological images, which could help to alleviate this impact. Thus, we developed a deep learning-based diagnostic algorithm to detect lymph node metastases of gastric adenocarcinoma and evaluated its performance. Methods. We randomly selected 20 patients with gastric adenocarcinoma who underwent surgery as definitive treatment and were found to be node metastasis-positive. HEMATOXYLIN-eosin (HE) stained glass slides, including a total of 51 metastasis-positive nodes, were retrieved from the specimens of these cases. Other slides with 776 metastasis-negative nodes were also retrieved from other twenty cases with the same disease that were diagnosed as metastasis-negative by the final pathological examinations. All glass slides were digitized using a whole-slide scanner. A deep-learning algorithm to detect metastases was developed using the data in which metastasis-positive parts of the images were annotated by a well-trained pathologist, and its performance in detecting metastases was evaluated. Results. Cross-validation analysis indicated an area of 0.9994 under the receiver operating characteristic curve. Free-response receiver operating characteristic curve (FROC) analysis indicated a sensitivity of 1.00 with three false positives. Further evaluation using an independent dataset also showed similar level of accuracies. Conclusion. This deep learning-based diagnosis-aid system is a promising tool that can assist pathologists involved in gastric cancer care and reduce their workload.

Clinical utility of artificial intelligence assistance in histopathologic review of lymph node metastasis for gastric adenocarcinoma

BACKGROUND

Advances in whole-slide image capture and computer image analyses using deep learning technologies have enabled the development of computer-assisted diagnostics in pathology. Herein, we built a deep learning algorithm to detect lymph node (LN) metastasis on whole-slide images of LNs retrieved from patients with gastric adenocarcinoma and evaluated its performance in clinical settings.

METHODS

We randomly selected 18 patients with gastric adenocarcinoma who underwent surgery with curative intent and were positive for LN metastasis at Chiba University Hospital. A ResNet-152-based assistance system was established to detect LN metastases and to outline regions that are highly probable for metastasis in LN images. Reference standards comprising 70 LN images from two different institutions were reviewed by six pathologists with or without algorithm assistance, and their diagnostic performances were compared between the two settings.

RESULTS

No statistically significant differences were observed between these two settings regarding sensitivity, review time, or confidence levels in classifying macrometastases, isolated tumor cells, and metastasis-negative. Meanwhile, the sensitivity for detecting micrometastases significantly improved with algorithm assistance, although the review time was significantly longer than that without assistance. Analysis of the algorithm's sensitivity in detecting metastasis in the reference standard indicated an area under the curve of 0.869, whereas that for the detection of micrometastases was 0.785.

CONCLUSIONS

A wide variety of histological types in gastric adenocarcinoma could account for these relatively low performances; however, this level of algorithm performance could suffice to help pathologists improve diagnostic accuracy.

Recent Advances in Sentinel Node Navigation Surgery for Early Gastric Cancer

Maintaining the postoperative quality of life (QOL) while ensuring curability without overtreatment is important in the treatment of early gastric cancer. Postoperative QOL is anticipated to be maintained through minimally invasive function-preserving gastrectomy in early gastric cancer. The concept of the sentinel lymph node (SN) basin is essential to maintain the curability of early gastric cancer using minimally invasive function-preserving gastrectomy. However, additional resection after surgery is difficult to perform in gastric cancer. Thus, the SN basin theory is important. Recently, a multicenter randomized phase III trial in South Korea (SENORITA trial) proved that laparoscopic sentinel node navigation surgery (LSNNS) for stomach preservation results in better postoperative QOL compared with standard gastrectomy in patients with early gastric cancer. LSNNS contributes to patients' QOL based on the concept that curability is not impaired. A multicenter nonrandomized phase III trial is ongoing in Japan, and oncologic safety is expected to be demonstrated. LSNNS has been established as a treatment option for selected patients with early gastric cancer, and its application will become widespread in the future.

Mapping Lymph Node during Indocyanine Green Fluorescence-Imaging Guided Gastric Oncologic Surgery: Current Applications and Future Directions

Huge strides have been made in the navigation of gastric cancer surgery thanks to the improvement of intraoperative techniques. For now, the use of indocyanine green (ICG) enhanced fluorescence imaging has received promising results in detecting sentinel lymph nodes (SLNs) and tracing lymphatic drainages, which make it applicable for limited and precise lymphadenectomy. Nevertheless, issues of the lack of specificity and unpredictable false-negative lymph nodes were encountered in gastric oncologic surgery practice using ICG-enhanced fluorescence imaging (ICG-FI), which restrict its application. Here, we reviewed the current application of ICG-FI and assessed potential approaches to improving ICG-FI.

History of the lymph node numbering system in the Japanese Classification of Gastric Carcinoma since 1962

The Japanese Classification of Gastric Carcinoma was established by the Japanese Research Society for Gastric Cancer in 1962. The latest 15th edition was published in 2017. One of its main features is that lymph nodes are numbered as stations. The number of groups has increased from 16 to 36 in 55 years. Seven groups (nos. 1, 2, 5, 7, 9, 10, and 15) were retained from the original classification. Nine groups (nos. 3, 4, 6, 8, 11, 12, 13, 14, and 16) were sub-divided into two or more groups. Furthermore, seven groups (nos. 17, 18, 19, 20, 110, 111, and 112) were added in the 6th, 11th, and 12th editions. This numbering system helps surgeons recognize the exact lymph nodes that need to be dissected. However, the numbering system has become extremely complicated. It is necessary to organize the historical background of each lymph node station and share the definitions clearly. This review focuses on nine anatomical zones around the stomach and summarizes the history of lymph node stations in the Japanese Classification of Gastric Carcinoma. Lymph node stations will continue to be modified in the future, and the historical background may be useful in future revisions.

Prognostic impact of lymph node micrometastasis in patients with gastric cancer

PURPOSE

The clinical significance of lymph node micrometastasis (LNMM) remains controversial in gastric cancer (GC). In this study, we investigated the prognostic impact of LNMM in patients with GC.

METHODS

A total of 624 patients with pathologically lymph node metastasis-negative (pN0) and N1 status (pN1) who underwent gastrectomy between 2004 and 2018 were enrolled in this retrospective study. The diameter of tumor cell clusters in metastatic lymph nodes was measured in 120 patients with pN1 GC.

RESULTS

Patients with lymph node tumors < 1500 μm in diameter (LNMM) had a significantly better prognosis than those with tumors ≥ 1500 μm in diameter (p = 0.012; log-rank test). Cox's proportional hazards model revealed that LNMM (p = 0.016), several dissected lymph nodes (p = 0.049), and the provision of adjuvant chemotherapy (p = 0.002) were independent prognostic factors for the overall survival of patients with pN1 GC. There was no significant difference in the overall survival between patients with LNMM who received chemotherapy and those who did not (p = 0.332).

CONCLUSIONS

LNMM is associated with a favorable prognosis and maybe an independent prognostic marker in patients with pN1 GC. LNMM in GC may be considered a factor preventing adjuvant chemotherapy.

Current status of function-preserving gastrectomy for gastric cancer

Early gastric cancer (EGC) has excellent postoperative survival outcomes; thus, one of the recent keywords in the treatment of EGC is "function-preserving gastrectomy (FPG)." FPG reduces the extent of lymphadenectomy and gastric resection without compromising the long-term prognosis. Proximal gastrectomy (PG) is an alternative to total gastrectomy (TG) for EGC in the upper-third of the stomach, in which the gastric reservoir, gastric acid secretion, and intrinsic factors are maintained. Distal gastrectomy (DG) with a small remnant stomach, namely subtotal gastrectomy (STG), is another option for upper EGC, where the function of the cardia and fundus is preserved. Pylorus-preserving gastrectomy (PPG) is a good alternative to DG for EGC in the middle-third of the stomach, where pyloric function is preserved. Following elucidation of the markedly low incidences of possible metastasis to lymph node stations where dissection is omitted, the oncological safety of these FPG procedures was clarified. Nutritional advantages of PG or STG over TG have been reported; however, the standardized reconstruction methods after PG are yet to be established, and it is important to devise methods to prevent postoperative gastroesophageal reflux and anastomotic complications regardless of the reconstruction method. Nutritional benefits of PPG compared with DG have also been clarified, in which reducing postoperative gastric stasis is important. For the further spread of these FPG procedures, several issues, such as precise evaluation of preserved function, confirmation of oncological safety, and standardization of the technique, should be addressed in future prospective randomized controlled trials.

Combination of endoscopic submucosal dissection and laparoscopic sentinel lymph node dissection in early mucinous gastric cancer: Role of lymph node metastasis

BACKGROUND

Recent evidence showed that combining endoscopic submucosal dissection (ESD) and laparoscopic sentinel lymph node dissection may avoid unnecessary gastrectomy in treating early mucinous gastric cancer (EMGC) patients with risks of positive lymph node metastasis (pLNM).

AIM

To explore the predictive factors for pLNM in EMGC, and to optimize the clinical application of combing ESD and sentinel lymph node dissection in a proper subgroup of patients with EMGC.

METHODS

Thirty-one patients with EMGC who had undergone gastrectomy with lymph node dissection were consecutively enrolled from January 1988 to December 2016. Univariate and multivariate logistic regression analyses were used to estimate the association between the rates of pLNM and clinicopathological factors, providing odds ratio (OR) with 95% confidence interval. And the association between the number of predictors and the pLNM rate was also investigated.

RESULTS

Depth of invasion (OR = 7.342, 1.127-33.256, P = 0.039), tumor diameter (OR = 9.158, 1.348-29.133, P = 0.044), and lymphatic vessel involvement (OR = 27.749, 1.821-33.143, P = 0.019) turned out to be significant and might be the independent risk factors for predicating pLNM in the multivariate analysis. For patients with 1, 2, and 3 risk factors, the pLNM rates were 9.1%, 33.3%, and 75.0%, respectively. pLNM was not detected in seven patients without any of these risk factors.

CONCLUSION

ESD might serve as a safe and sufficient treatment for intramucosal EMGC if tumor size ≤ 2 cm, and when lymphatic vessel involvement is absent by postoperative histological examination. Combining ESD and sentinel lymph node dissection could be recommended as a safe and effective treatment for EMGC patients with a potential risk of pLNM.

Evaluation of postoperative quality of life by PGSAS-45 following local gastrectomy based on the sentinel lymph node concept in early gastric cancer

BACKGROUND

The usefulness of sentinel node navigation surgery (SNNS) for early gastric cancer has been demonstrated in a multicenter prospective study. However, quality of life (QOL) after local resection remains unclear. This present study investigated QOL after local resection and distal gastrectomy.

METHODS

We examined 69 patients who underwent laparoscopic distal gastrectomy (LADG) (n = 44) and laparoscopic local resection (LLR) (n = 25) in our hospital between September 2011 and May 2018. We conducted a combination of laparoscopic and endoscopic approaches to neoplasia with non-exposure technique (CLEAN-NET) with SNNS as LLR. All patients had pStage I or II and none had received adjuvant chemotherapy. We evaluated QOL using the postgastrectomy syndrome assessment scale questionnaire (PGSAS-45) 1, 6, and 12 months after surgery.

RESULTS

In PGSAS-45, no significant differences were observed between LLR and LADG at 1 and 6 months after surgery. At 12 months, the LLR group scored better for some of the subscales (SS). In the endoscopic evaluation, the LLR group showed significant improvements in residual gastritis at 6 months (P = 0.006) and esophageal reflux and residual gastritis at 12 months (P = 0.021 and P = 0.017). A significant difference was observed in the prognostic nutritional index, which was assessed using serum samples, between the two groups at 6 months (P = 0.028). The body weight ratio was better in the LLR group than in the LADG group at 6 and 12 months (P = 0.041 and P = 0.007, respectively).

CONCLUSIONS

CLEAN-NET with SNNS preserved a better QOL and nutrition status than LADG in patients with early gastric cancer.

Essential updates 2017/2018: Recent topics in the treatment and research of gastric cancer in Japan

Recent developments in diagnostic technology, accumulated clinical effort and established evidence have boosted early detection and drastically improved early and long-term outcomes of gastric cancer. However, gastric cancer continues to be one of the most aggressive and life-threatening malignancies among all cancers and is a global health problem. Between January 2017 and December 2018, various fascinating reports of managements and research were published, including the new 15th Japanese Classification of Gastric Carcinoma reflecting the 8th American Joint Committee on Cancer/Union for International Cancer Control (AJCC/UICC) tumor, node and metastasis (TNM) classification (October 2017) and the new Gastric Cancer Treatment Guidelines version 5 (January 2018). Moreover, pivotal molecular features of gastric cancer were clarified by the worldwide cancer genome project, and various treatment targets and biomarkers such as circulating DNAs and microRNAs were detected. Novel treatment options using programmed cell death protein 1 immune checkpoint inhibitors have been started. In this review, we summarize the recent topics of classification, guidelines, and clinical and basic research in order to bring new insights to gastric cancer treatment.

Clinical outcomes of minimally invasive treatment for early gastric cancer in patients beyond the indications of endoscopic submucosal dissection

BACKGROUND

Endoscopic submucosal dissection (ESD) with laparoscopic sentinel lymph node dissection (ESN) and endoscopic full-thickness gastric resection with laparoscopic sentinel lymph node dissection (Hybrid-natural orifice transluminal endoscopic surgery, Hybrid-NOTES) are minimally invasive treatment options for early gastric cancer (EGC) beyond the indications of ESD. This study aimed to evaluate the short- and long-term clinical outcomes of ESN and Hybrid-NOTES.

METHODS

We retrospectively analyzed patients who had undergone ESN or Hybrid-NOTES for EGC from January 2009 to March 2013. A total of 48 patients, including 21 undergoing ESN and 27 undergoing Hybrid-NOTES, were enrolled. All patients had cancer stage T1N0M0, EGC less than 5 cm in size, and suspected submucosal invasion according to imaging or biopsy-proven diffuse-type histology.

RESULTS

In ESN and Hybrid-NOTES, the curative resection rates were 76.5% and 90.9% of patients, respectively. In the ESN group, 5 patients underwent an additional gastrectomy (1 for lymph node metastasis (LNM), 3 for surgical complications, and 1 for noncurative resection). In the Hybrid-NOTES group, 6 patients underwent additional gastrectomy, (1 for LNM, 3 for surgical complications, and 2 for noncurative resection). Of the 37 patients who were followed up in the long-term (a median follow-up of 59.8 months), one was found to have liver metastasis after ESN and received palliative chemotherapy.

CONCLUSIONS

ESN and Hybrid-NOTES have shown favorable long-term outcomes despite their technical limitations. These methods may be utilized as a bridge between ESD and gastrectomy in cases of EGC with a high risk of LNM beyond the ESD indications.