[New classification of the T category for pancreatic cancer]

The General Rules for the Study of Pancreatic Cancer (4th edition) is widely used in Japan, but several problems have been detected. One is the complexity of classification of the T category of peripancreatic invasion. This study was undertaken to simplify the classification of the T category. In 145 patients who underwent resection of pancreatic cancer, we analyzed the prognosis of those with invasion and without invasion based on seven factors of peripancreatic invasion. Furthermore, we selected three factors (S, invasion to the anterior pancreatic capsule; RP, invasion to the retroperitoneal tissue; and PL, invasion to the extrapancreatic nerve plexus) as prognostic factors by means of stepwise multivariate linear regression analysis. Subsequently we established a new classification of the T category: T1, without invasion in all three factors; T2, with invasion in only one of the three factors; and T3, with invasion in two or three factors. The prognoses of the same patients were analyzed retrospectively, and 1-, 3-, and 5-year survival rates were 100%, 88%, and 44% in T1, 76%, 30%, and 18% in T2, and 27%, 4%, 3% in T3 patients, respectively. In conclusion, we suggest that our new classification of the T category is simple and useful for the assessment of the prognosis in pancreatic cancer.