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[Prognostic factors of lymph node-negative metastasis gastric cancer].

OBJECTIVE
To investigate the prognostic factors of patients with lymph node-negative metastasis gastric cancer (pN0).


METHODS
Clinicopathological data of patients with pN0 gastric cancer who underwent radical operation at the Department of Surgical Oncology, The First Hospital of China Medical University from May 1980 to August 2012 were collected and analyzed retrospectively.


INCLUSION CRITERIA
(1) Patients were diagnosed as gastric adenocarcinoma; (2) Postoperative pathology confirmed T1a to 4bN0M0 gastric cancer; (3) Total number of harvested lymph node was more than 15. The patients, who died within 1 month after the operation, died of other diseases, had remnant gastric cancer, or had incomplete follow-up data, were excluded. Univariate analysis was used to analyze the clinical factors that may influence the prognosis of patients with stage pN0 gastric cancer, then, those significant variables were entered into the Cox's proportional hazards regression model for multivariate analysis to obtain the independent prognostic factors for patients with pN0 gastric cancer finally. Furthermore, the prognosis of patients with pN0 advanced gastric cancer (invasive depth ≥ T2) were analyzed using the same method.


RESULTS
A total of 610 patients with pN0 gastric cancer were enrolled in the study, including 441 males and 169 females with age ranging from 19 to 83 (mean 56.4±11.0) years, D1 lymph node dissection in 45 cases, D2 lymph node dissection in 543 cases, D3 lymph node dissection in 22 cases, and 384 cases of advanced gastric cancer. The overall followed-up was 1 to 372 (median 32) months. Ninety cases (14.8%) were dead during the follow-up. The median survival was 277.7(95%CI: 257.6 to 297.8) months, and the 1-, 3-, 5-year survival rates were 96.5%, 87%, 83.2%. Univariate analysis showed that tumor diameter, depth of invasion, gross type, lymph node dissection and lymph vessel cancer embolus were related to the prognosis (all P<0.05). The 5-year survival rate of patients with tumor diameter >4 cm was significantly lower than those with tumor diameter ≤4 cm (75.6% vs. 87.8%, P=0.000). The 5-year survival rates of T1a, T1b, T2, T3 and T4 were 98.4%, 92.8%, 84.2%, 61.0% and 31.4% respectively, and the difference was statistically significant (P=0.000). In gross type, 5-year survival rate of early gastric cancer was 96.0%, and of Borrmann I( to IIII( type gastric cancer was 100%, 83.4%, 73.7% and 68.9% respectively, whose difference was statistically significant(P=0.000). The 5-year survival rates in patients undergoing lymph node dissection D1, D2 and D3 were 100%, 83.3% and 58.7%, and the difference was significant (P=0.005). The 5-year survival rate of patients with positive lymphatic cancer embolus was lower than those with negative ones (69.4% vs. 86.9%, P=0.000). Multivariate analysis showed that the gross type [Borrmann II(/early gastric cancer: HR(95% CI)=15.129(3.284 to 69.699), Borrmann III(/early gastric cancer: HR(95% CI)=14.613 (3.292 to 64.875), Borrmann IIII(/early gastric cancer: HR (95% CI)=15.430 (2.778 to 85.718),Borrmann IIIII(/early gastric cancer: HR(95%CI)=12.604 (1.055 to 150.642), P=0.025] and the positive lymphatic cancer embolus [HR(95% CI)=3.241 (2.056 to 5.108), P=0.000] were the independent prognostic factors of patients with pN0 gastric cancer. For pN0 patients with advanced gastric cancer, multivariate analysis showed that the depth of invasion [stage T3/stage T2: HR(95%CI)=1.520 (0.888 to 2.601), stage T4/stage T2: HR(95%CI)=2.235(1.227 to 4.070); P=0.031] and the positive lymphatic cancer embolus [HR(95%CI)=3.065 (1.930 to 4.868); P=0.000] were the independent risk factors influencing the prognosis.


CONCLUSIONS
Positive lymphatic cancer embolus and worse gross pattern indicate poorer prognosis of patients with pN0 gastric cancer, which may be used as effective markers in evaluating the prognosis. As for pN0 advanced gastric cancer, invasion depth and positive lymphatic cancer embolus can play a more important role in the prediction.