OBJECTIVETo investigate the value of preoperative abdominal contrast-enhanced multiple-row detector computed tomography (ceMDCT) in predicting the postoperative 1-year disease-free survival (DFS) for gastric cancer.

METHODSBetween January 2009 and December 2015, 237 gastric cancer patients at Peking University People's Hospital with complete preoperative clinical, image and follow-up data were enrolled in this retrospective study.

INCLUSION CRITERIA(1) primary gastric cancer was confirmed by pathology; (2) radical gastrectomy and D2 lymph node dissection were performed;(3) patients underwent preoperative ceMDCT. Patients with gastric stump cancer, concurrent metastasis, other malignancies, and undergoing neoadjuvant treatment were excluded. According to ceMDCT examination with or without ctEMVI (extramural venous invasion), patients were divided into ctEMVI-positive and ctEMVI-negative group. ctEMVI-positive was defined as that there was a continuous tubular and nodular soft tissue filling defect from the tumor to the adjacent blood vessel lumen in ceMDCT, suggesting the tumor directly invaded the blood vessels outside the muscularis propria of the gastrointestinal smooth muscle. Log-rank test was used to compare differences in 1-year DFS between ctEMVI-positive group and ctEMVI-negative group. According to the 8th edition of the American Joint Committee on Cancer (AJCC), the T staging in ceMDCT (ctT) and lymph node metastasis (lymph nodes with shorter diameter > 8 mm) were determined. The patients were subdivided into four subgroups, ctT4N(+), ctT4N(-), ctT1-3N(+), and ctT1-3N(-), to further compare the difference in postoperative 1-year DFS between ctEMVI-positive and -negative patients in each subgroups. Kaplan-Meier univariate analysis was performed on preoperative imaging data (ctT, ctN, ctEMVI, tumor location/growth pattern, and ctSize). Cox proportional hazard regression was used to find the independent risk factors of 1-year DFS rate. According to the number of independent risk factors, the patients were classified to different risk stratifications. The difference of 1-year DFS rate between different risk stratifications was compared.

RESULTSAccording to the results of ceMDCT, 72 patients (30.4%) were divided into the ctEMVI-positive group and 165 patients(69.6%) into the ctEMVI-negative group. The ctEMVI-positive group had significantly lower 1-year DFS rate (55.3%) than the ctEMVI-negative group (90.2%) (χ²=40.17, P<0.001). The 1-year DFS in the ctEMVI-positive ctT4N(+) subgroup was 34.5%, which was significantly lower than that of the ctMVI-negative ctT4N(+) subgroup (85.3%) (χ²=19.13, P<0.001). In the ctEMVI-positive ctT1-3N(-) subgroup, the 1-year DFS was 77.8%, which was also significantly lower than 98.5% of the ctEMVI-negative ctT1-3N(-) subgroup(χ²=15.09, P=0.003). In Cox proportional hazards regression analysis, ctT, ctN and ctEMVI were identified as independent prognostic factors of 1-year DFS with hazard ratio (HR) of 3.351(95%CI:1.249-8.986, P=0.017), 1.987(95%CI:1.085-3.637, P=0.027) and 3.398(95%CI:1.785-6.469, P<0.001), respectively. Risk classification was carried out according to the number of independent risk factors (ctT, ctN and ctEMVI). Grade 0 had no independent risk factors, grade 1 had one independent risk factor, grade 2 had two independent factors and grade 3 had 3 independent risk factors. The risk grading result showed that the numbers of patients form grade 0 to 3 were 71, 65, 68, 33, respectively, and the 1-year DFS rates were 98.5%, 82.1%, 79.0%, 34.5%, respectively(P<0.001). With the increase of the number of independent risk factors, 1-year DFS rate decreased gradually in patients with gastric cancer (P<0.001). Differences of 1-year DFS between grade 0 and grade 1(P=0.002), between grade 2 and grade 3(P<0.001) were both significant. Meanwhile the difference between grade 1 and grade 2 was not significant (P=0.578).

CONCLUSIONSctEMVI, ctT and ctN defined by preoperative ceMDCT are independent risk factors for the prognosis of gastric cancer. With the increase of risk factors, the 1-year DFS decreases gradually.