Characteristics of intramural metastasis in gastric cancer

Intramural metastasis (IM) in gastric cancer is rare. However, it often occurs with esophageal squamous cell carcinoma and has been reported to have a poor prognosis.

In 4,714 cases of gastric cancer that underwent gastrectomy, the clinicopathological features and postoperative prognoses of 29 cases with IM were evaluated and compared with 2,770 cases of advanced gastric cancer without IM.

Of the 4,714 cases, 29 (0.6 %) were histopathologically diagnosed with gastric cancer with IM. There were significant differences in the number of lymph node metastases, capillary invasion, and stage grouping between cases with IM and advanced gastric cancer without IM. Metastasis size was approximately within 2 cm, and many metastases occurred within 2 cm of the primary lesion. Multiple metastases were observed in 38 % of cases and occurred mainly in the submucosa and muscularis propria. IM was detected preoperatively in 17.2 % of cases and was present equally on both sides of the primary lesion. Nine cases had IM outside the stomach. The median survival time with IM was significantly less than in cases of advanced gastric cancer without IM (p < 0.0001). A subgroup of cases with IM within 1 cm of the primary lesion had a relatively favorable prognosis.

The presence of IM is thought to be one of the most important prognostic factors in gastric cancer. Aggressive resection is recommended to increase long-term survival if curative resection is possible.