The importance of neural invasion (NI) as a prognostic factor in diffuse invasive gastric cancer.

The relationship between histological factors, including neural invasion (NI), and survival rates in patients with Borrmann type IV diffuse invasive gastric cancer was examined to determine the significance of NI as a prognostic factor. NI was studied histochemically in 75 patients who underwent resection after 1982, 37 of whom underwent curative resection. The 3-year and 5-year survival rates of the 37 patients who underwent curative resection were 37.2% and 12.7%, respectively. Recurrence was detected as peritoneal dissemination in 19 of those patients (82.6%), and the most significant prognostic factor was the depth of wall invasion (P < 0.01). While NI (P = 0.06) and lymph node metastasis (P = 0.09) appeared to be prognostic factors, there were no significant differences. Therefore, the depth of wall invasion was classified as T2 and T3 or 4 to examine the association of NI and lymph node metastasis with prognosis, whereby NI was shown to be a significant prognostic factor in T2. In conclusion, NI may be a significant prognostic factor in patients with wall invasion of T2 without serosal invasion, as it provides a pathway for the progression to peritoneal dissemination.