With the introducing of neoadjuvant therapy, it becomes ever more important to evaluate the preoperative TNM (cTNM) stage accurately facilitating preoperative treatment as well as the adjuvant therapy.

At present, the recommendation of neoadjuvant chemotherapy varies among guidelines especially between eastern and western countries. According to the updated Japanese gastric cancer treatment guidelines (ver.5), neoadjuvant chemotherapy is the recommended standard procedure for patients with cT2-4 stages. However, the acknowledgement of preoperative therapy accompanied by the higher risk of overtreatment. As mentioned in JCOG1302-A, the overall precision rate in cT staging is 38.8%. Patients diagnosed with pI stages postoperatively account for 6.5% in cT3-4N+ treatment indicating more likely to avoiding the overtreatment comparing to patients with other cT stages.

Inspired by JCOG1302-A, this multicentre study prospectively collect data in preoperative TNM staging assessment using CT(computed tomography, CT) scan and the postoperative TNM (pTNM) staging according to histopathologically examination. By analyzing the accordance between the cTNM and pTNM, this study aims to evaluate the current accuracy of the cTNM staging in china, verifying the proportion of pI stages less than 5% in cIII stage diagnosis patients, learning the overtreating rate in neoadjuvant chemotherapy in China and furthermore, to discover the scope of beneficiaries for neoadjuvant chemotherapy.

OBJECTIVES:

I. Confirm the inclusion of pathological stage I (pI) among clinical stage III(T3-4aNx) (cIII) diagnosis patients less than 5% II. Figure out the suitable criterion of NAC and avoid overtreatment, by examining the rate of pI rate in different diagnostic criterion groups, including cIII, TxNy(x+y>4), cN1-3, cT3-4.

III. Evaluate the current state of diagnostic accuracy of preoperative CT staging in china.

OUTLINE:

This is a prospective, multi-centers, cohort study of clinical TNM staging diagnostic accuracy.

Patients are divided into 3 preoperative stage groups according to AJCC 8th edition (cI, cII, cIII) preoperatively. All patients receive the D2 gastrectomy after cTNM diagnosis and the pathological stages is given following surgery.

The concordance of preoperative staging is evaluated in each cohorts as well as the subgroups to obtain the accuracy rate. The pI proportion will calculate in each latent criterion groups to assess the suitable NAC criteria.

PROJECTED ACCRUAL: A total of 968 patients will be accrued for this study within two years.

Inclusion Criteria:

• Histological prove of adenocarcinoma of the stomach by endoscopy
• Preoperative imaging data by contrast-enhanced CT and clinical TNM stages were given
• No evidence of stage IV disease
• No previous gastrectomy or preoperative treatment.

Exclusion Criteria:

• Discovery of distant metastasis (stage IV) during surgery
• Number of retrieved lymph node less than 15

Subjects with endoscopically biopsy-proven adenocarcinoma of the stomach and with contrast-enhanced CT cI-III diagnosis prior to surgery will receive treatment.