Retrospective Analysis of Early Gastric Cancer Patients Based on Prospective Clinical Dataset

Overall survival is defined as the time from the date of surgery to death from any cause.

Recurrence-free survival is defined as the time from the date of surgery to the first occurrence of disease recurrence.

Progression-free survival is defined as the time from the date of surgery to the first occurrence of either disease progression or death from any cause. Disease progression includes recurrence, metastasis, or progression of residual disease.

Incidence and severity of complications occurring within 30 days following surgery, graded according to the Clavien-Dindo classification.

All-cause mortality occurring within 30 days after surgery, ascertained from medical records and follow-up data.

Rate of unscheduled reoperation within 30 days after the initial surgery, identified from surgical records and inpatient documentation.

Rate of unplanned hospital readmission within 30 days after discharge following the initial surgery, identified from readmission records.

Total duration of the surgical procedure, extracted from operative records.

Estimated total volume of blood loss during the surgical procedure, extracted from operative records and anesthesia documentation.

Total number of days from the date of surgery to hospital discharge, extracted from inpatient medical records.

Maximum diameter of the primary tumor (in millimeters) measured by preoperative gastroscopy.

Macroscopic type of the primary tumor assessed by preoperative gastroscopy, classified as elevated (0-I), flat (0-IIa, IIb, IIc), or depressed (0-III) types according to the Paris classification.

Depth of tumor invasion assessed by preoperative contrast-enhanced CT, categorized as cT1, cT2, cT3, or cT4 according to the AJCC 8th edition TNM staging system.

Lymph node metastasis status assessed by preoperative contrast-enhanced CT, categorized as cN0, cN1, cN2, or cN3 according to the AJCC 8th edition TNM staging system.

The number of suspicious metastatic lymph nodes identified during the preoperative enhanced CT examination.

Pathological depth of tumor invasion assessed according to AJCC 8th edition pT category (pT1a, pT1b, pT2, pT3, or pT4) based on postoperative histopathological examination of the resected specimen.

Pathological lymph node metastasis status assessed according to AJCC 8th edition pN category (pN0, pN1, pN2, or pN3) based on postoperative histopathological examination.

Total number of lymph nodes retrieved and examined from the resected specimen.

Total number of lymph nodes with pathologically confirmed metastasis.

Anatomical distribution of pathologically confirmed metastatic lymph nodes identified in the resected specimen, categorized by lymph node station (e.g., No.1, No.3, No.4sb, No.7, etc.) according to the Japanese Gastric Cancer Association (JGCA) classification system. Data will be extracted from postoperative pathology reports.

Proportion of positive lymph nodes among total lymph nodes examined (number of positive lymph nodes / total lymph nodes examined × 100%).

Histological differentiation of gastric adenocarcinoma, categorized as well-differentiated, moderately-differentiated, poorly-differentiated, or undifferentiated, based on postoperative pathology.

Presence or absence of lymphatic and/or vascular invasion assessed by postoperative histopathological examination.

Presence or absence of perineural invasion assessed by postoperative histopathological examination.

Proportion of patients with no residual tumor microscopically confirmed on both the primary tumor resection margins and resected lymph nodes, assessed by postoperative pathological examination.

It is evaluated by gastric emptying half-time (GET₁/₂) measured via radionuclide scintigraphy.

Helicobacter pylori infection status determined by ¹³C/¹⁴C urea breath test.

The European Organization for Research and Treatment of Cancer Quality of Life Questionnaire-Core 30(EORTC-QLQ-C30) includes 30 items measuring functional, symptomatic, and global quality-of-life domains. Scores are transformed to a 0-100 scale, with higher scores indicating better quality of life.

The European Organization for Research and Treatment of Cancer Quality of Life Questionnaire-Stomach Cancer Module 22(EORTC-QLQ-STO22) supplement contains 22 items assessing symptoms and concerns specific to gastric cancer. Scores are transformed to a 0-100 scale, with higher scores indicating greater symptom burden.

The Postgastrectomy Syndrome Assessment Scale 45(PGSAS-45), consisting of 45 items, will be used to comprehensively evaluate postgastrectomy symptoms, digestive status, and daily life functions. All subscale scores are linearly transformed to a 0-100 range. For symptom-related subscales, higher scores indicate greater symptom burden; for functional and quality of life subscales, higher scores indicate better functioning or quality of life.

It is a combined score based on serum albumin level and total lymphocyte count. It is calculated as 10 × serum albumin (g/dL) + 0.005 × total lymphocyte count (cells/μL). Higher scores indicate better nutritional and immunological status.

It will be measured by serum C reactive protein (CRP) level.

Time from the date of surgery to the first passage of flatus, indicating recovery of gastrointestinal motility. Data will be extracted from postoperative recovery records.

Time from the date of surgery to the resumption of oral intake (liquid or solid diet), extracted from postoperative dietary records.