[Prognostic value of the tumor deposit in N0 gastric cancer by propensity score matching analysis].

OBJECTIVE

To investigate the prognostic value of tumor deposits(TD)in N0 stage gastric cancer.

METHODS

A retrospective case-control study was performed on clinicopathological data of 751 N0 stage gastric cancer patients who underwent subsequent R0 gastrectomy from January 2011 to February 2013 at Zhengzhou University Affiliated Tumor Hospital. Patients were divided into TD-negative group (688 cases) and TD-positive group (63 cases). Propensity score matching was used to balance the covariances between the two groups, such as age, gender, differentiation degree, tumor location, T stage, perineural invasion, lymphovascular invasion, extent of resection, tumor size, surgical procedure,and chemotherapy. Matching was performed by the minimal adjacent method of 1:2 pairing. The survival analysis was carried out using Kaplan-Meier method,and differences between the curves were detected by log-rank test. Cox proportional hazard model was used to perform univariate analysis and multivariate analysis.

RESULTS

After matching,56 patients were allocated into the TD-positive group and 112 patients into the TD-negative group, and the baseline of clinicopathological data of 2 groups matched well (all P>0.05). The median follow-up time was 55.2 (12.0-83.2) months, and 3 patients were lost to follow-up (died of other diseases). In TD-positive group, 38 patients died of gastric cancer and 1 died of other disease. In TD-negative group, 52 patients died of gastric cancer and 2 died of other diseases. The TD-positive group had lower 5-year survival rate than TD-negative group (31.0% vs. 52.9%,χ²=6.230, P=0.014). Subgroup analysis showed that the 5-year survival rate of T1-2 stage TD-positive patients was significantly lower than that of T1-2 stage TD-negative patients (47.1% vs. 92.6%, χ²=11.433,P<0.001),while the difference between two groups with T3-4 stage (23.8% vs. 40.0%, χ²=2.995,P=0.084)was not significant. In patients receiving chemotherapy, the 5-year survival rate of TD-positive group was significantly lower than that of TD-negative group(34.1% vs. 54.8%, χ²=4.122, P=0.042). Further subgroup analysis showed that patients receiving postoperative chemotherapy of TD-positive group both in T1-2 stage (63.6% vs. 100%, χ²=3.830,P=0.048) and in T3-4 stage (24.2% vs. 48.4%, χ²=4.740,P=0.029) had significantly lower 5-year survival rates than those of TD-negative group. However,T1-2 stage TD-positive patients receiving chemotherapy had significantly higher 5-year survival rate as compared to those without receiving chemotherapy(63.6% vs. 16.7%, χ²=5.474,P=0.019).Univariate analysis revealed T stage (HR=1.829, 95%CI:1.490-2.245, P<0.001),perineural invasion (HR=2.620, 95%CI:1.617-4.246,P<0.001),tumor size (HR=1.646, 95%CI:1.078-2.512, P=0.021),TD(HR=1.691,95%CI:1.112-2.572,P=0.014) were associated with the prognosis of patients with gastric cancer. Multivariate analysis showed TD-positive (HR=2.035, 95%CI:1.325-3.126, P=0.001), later T stage (HR=1.812, 95%CI: 1.419-2.313,P<0.001), perineural invasion (HR=1.782,95%CI:1.058-3.002,P=0.030) were independent risk factors for the prognosis of gastric cancer.

CONCLUSIONS

TD is an independent risk factor for N0 stage gastric cancer,and may be closely related to T stage. Patients with TD-positive stage T1-2 should receive chemotherapy, but the prognosis of TD-positive patients undergoing adjuvant chemotherapy is poorer as compared to TD-negative patients. Therefore, more individualized treatments should be administrated.