OBJECTIVETo evaluate the rationality of T staging of gastric cancer with transverse mesocolon invasion.

METHODSData of 808 patients with primary gastric cancer undergoing surgical treatment was screened from the Data base of Gastric Cancer of Sun Yat-sen University, from April 1996 to October 2009. According to the information of transverse mesocolon invasion, all cases were divided into groups NOI (T4a stage, non organ invasion, n = 638), NTMI (T4b stage, non transverse mesolon invasion, with organ invasion, n = 126), and TMI (transverse mesocolon invasion, n = 44). The clinicopathological features, surgical procedure and prognosis were compared among the three groups.

RESULTSNo significant difference was found in gender, age, lymph node metastasis, hepatic metastasis, tumor's Borrmann type, histological type, differentiation degree, value of serum CEA among the 3 groups (all P > 0.05). In the groups NOI, NTMI and TMI, the ratio of mean tumor diameter ≥ 5 cm was 39.0% (249/638), 61.1% (77/126) and 54.5% (24/44), respectively; the ratio of distal metastasis was 11.9% (76/638), 30.2% (38/126) and 43.2% (19/44), respectively; the ratio of peritoneal metastasis was 8.2% (52/638), 26.2% (33/126) and 38.6% (17/44), respectively; the ratio of TNM IV stage was 25.4% (162/638), 84.7% (107/126) and 93.7% (41/44), respectively; and the ratio of radical resection was 92.0% (587/638), 69.8% (88/126) and 77.3% (34/44), respectively; all with significant differences (P < 0.01), and the results of pairwise comparisons (Bonferroni correction, significant level α = 0.05/3 = 0.0167) showed that these parameters were significantly different between groups NOI and TMI (P < 0.0167), but non-significant between groups NTMI and TMI (P > 0.0167). The median survival time was 42.0, 16.4 and 19.0 months in the groups NOI, NTMI and TMI, respectively (P < 0.01), and the results of pairwise comparison showed that the prognosis were significant different between the groups NOI and TMI (P < 0.01), but non-significant between the groups NTMI and TMI (P > 0.05). In the cases who received radical resection, the median survival time was 47.9, 23.5 and 21.4 months in the groups NOI, NTMI and TMI, respectively (P < 0.01), and the results of pairwise comparison showed that the prognosis was significantly different between the groups NOI and TMI (P < 0.05), but not significant between groups NTMI and TMI (P > 0.05).

CONCLUSIONSThe tumor size, distal meatastasis, peritoneal metastasis, TNM stage, surgical procedure and prognosis of gastric cancer with transverse mesocolon invasion are similar to that of T4b gastric cancer, but are significantly different from that of T4a gastric cancer. Gastric cancer with transverse mesocolon invasion should be reclassified as T4b stage.