Pretreatment diagnosis factors associated with overtreatment with surgery in patients with differentiated-type early gastric cancer

Application of artificial intelligence for diagnosis of early gastric cancer based on magnifying endoscopy with narrow-band imaging

Although magnifying endoscopy with narrow-band imaging is the standard diagnostic test for gastric cancer, diagnosing gastric cancer using this technology requires considerable skill. Artificial intelligence has superior image recognition, and its usefulness in endoscopic image diagnosis has been reported in many cases. The diagnostic performance (accuracy, sensitivity, and specificity) of artificial intelligence using magnifying endoscopy with narrow band still images and videos for gastric cancer was higher than that of expert endoscopists, suggesting the usefulness of artificial intelligence in diagnosing gastric cancer. Histological diagnosis of gastric cancer using artificial intelligence is also promising. However, previous studies on the use of artificial intelligence to diagnose gastric cancer were small-scale; thus, large-scale studies are necessary to examine whether a high diagnostic performance can be achieved. In addition, the diagnosis of gastric cancer using artificial intelligence has not yet become widespread in clinical practice, and further research is necessary. Therefore, in the future, artificial intelligence must be further developed as an instrument, and its diagnostic performance is expected to improve with the accumulation of numerous cases nationwide.

Application of artificial intelligence-driven endoscopic screening and diagnosis of gastric cancer

The landscape of gastrointestinal endoscopy continues to evolve as new technologies and techniques become available. The advent of image-enhanced and magnifying endoscopies has highlighted the step toward perfecting endoscopic screening and diagnosis of gastric lesions. Simultaneously, with the development of convolutional neural network, artificial intelligence (AI) has made unprecedented breakthroughs in medical imaging, including the ongoing trials of computer-aided detection of colorectal polyps and gastrointestinal bleeding. In the past demi-decade, applications of AI systems in gastric cancer have also emerged. With AI's efficient computational power and learning capacities, endoscopists can improve their diagnostic accuracies and avoid the missing or mischaracterization of gastric neoplastic changes. So far, several AI systems that incorporated both traditional and novel endoscopy technologies have been developed for various purposes, with most systems achieving an accuracy of more than 80%. However, their feasibility, effectiveness, and safety in clinical practice remain to be seen as there have been no clinical trials yet. Nonetheless, AI-assisted endoscopies shed light on more accurate and sensitive ways for early detection, treatment guidance and prognosis prediction of gastric lesions. This review summarizes the current status of various AI applications in gastric cancer and pinpoints directions for future research and clinical practice implementation from a clinical perspective.

A "Just Enough" Gross Proximal Margin Length Ensuring Pathologically Complete Resection in Distal Gastrectomy for Gastric Cancer

Introduction

The objective of this study is to determine a "just enough" gross proximal margin (PM) length to ensure a pathologically negative PM in distal gastrectomy for gastric cancer. There is a discrepancy between the gross and pathological proximal boundaries of gastric cancer. We must transect the stomach maintaining some safety margins to obtain a pathologically negative PM. However, we have no standard to indicate where to transect the stomach.

Methods

Patients undergoing distal gastrectomy for gastric cancer were enrolled. A new parameter named ΔPM, which corresponded to the pathological extension proximal to the gross tumor boundary toward the resection stump, was evaluated. The number of patients was counted in each ΔPM range of 1-cm increments. The maximum ΔPM was defined as the first value at which the number of patients became 0, and it was determined as the recommended gross PM length for each disease type.

Results

In cT1, 259 and 330 patients were assigned to differentiated (Dif) and undifferentiated types (Und), respectively. The maximum ΔPM was 20 mm for Dif and 40 mm for Und. In cT2-4, 194 and 490 patients were assigned to the expansive (Exp) and infiltrative (Inf) growth types. The maximum ΔPM was 30 mm for Exp. The maximum ΔPM was 50 mm for Inf of less than 80 mm and 60 mm for Inf of 80 mm or more.

Conclusions

A newly recommended gross PM length to ensure pathologically negative PMs in distal gastrectomy for each gastric cancer type was determined.

Role of prophylactic hyperthermic intraperitoneal chemotherapy in patients with locally advanced gastric cancer

BACKGROUND

Gastric cancer is the second most common malignant tumor in China, ranking third among all malignant tumor mortality rates. Hyperthermic intraperitoneal chemotherapy (HIPEC) has been shown to increase significantly the effectiveness of intraperitoneal chemotherapeutic drugs, prolong the action time of these drugs on intraperitoneal tumor cells, and enhance their diffusion in tumor tissues. HIPEC may be one of the best choices for the eradication of residual cancer cells in the abdominal cavity.

AIM

The aim of this study was to study the role of preventive HIPEC after radical gastrectomy.

METHODS

A prospective analysis was performed with patients with cT₄N_0-3M₀ gastric cancer to compare the effects of postoperative prophylactic HIPEC plus intravenous chemotherapy with those of routine adjuvant chemotherapy. Patients’ medical records were analyzed, and differences in the peritoneal recurrence rate, disease-free survival time, and total survival time between groups were examined.

RESULTS

The first site of tumor recurrence was the peritoneum in 11 cases in the conventional adjuvant chemotherapy group and in 2 cases in the HIPEC group (P = 0.020). The 1-year and 3-year disease-free survival rates were 91.9% and 60.4%, respectively, in the conventional adjuvant chemotherapy group and 92.1% and 63.0%, respectively, in the HIPEC group. The 1-year and 3-year overall survival rates were 95.2% and 66.3%, respectively, in the conventional adjuvant chemotherapy group and 96.1% and 68.6%, respectively, in the HIPEC group. No significant difference in postoperative or chemotherapy complications was observed between groups.

CONCLUSION

In patients with cT₄N_0-3M₀ gastric cancer, prophylactic HIPEC after radical tumor surgery is beneficial to reduce peritoneal tumor recurrence and prolong survival.

HER2 as a potential biomarker of lymph node metastasis in undifferentiated early gastric cancer

Human epidermal growth factor receptor 2 (HER2) is implicated in several cancers, including gastric cancer. However, limited data are available regarding its clinical significance in early gastric cancer (EGC). We evaluated the clinical significance of HER2 overexpression in patients with EGC. We retrospectively reviewed 727 patients who underwent surgical treatment for EGC between October 2010 and August 2017. HER2 expression was analysed in 680 EGC cases by immunohistochemistry and classified as negative (0 and 1+), equivocal (2+), or positive [overexpression (3+)]. Among patients with differentiated EGC, the number of patients with HER2 overexpression was not significantly different from that of HER2-negative patients in terms of age, sex, tumour size, location, gross type, depth of invasion, presence of lymphovascular invasion (LVI), and presence of lymph node metastasis (LNM). However, in patients with undifferentiated EGC, HER2 overexpression was significantly correlated with LVI and presence of LNM compared with HER2-negative patients. Multivariate analysis indicated HER2 overexpression as a good predictive marker of LNM in patients with undifferentiated EGC. HER2 expression is associated with LNM in undifferentiated EGC. Therefore, the importance of HER2 overexpression in EGC should not be overlooked, and further studies are needed to identify its clinical significance.