Tumor size matters in new TNM staging of pancreatic cancer

Last Updated: 2017-10-23

By Will Boggs MD

NEW YORK (Reuters Health) - The new eighth edition of the Union for International Cancer Control classification of TNM (tumor-node-metastasis) staging for pancreatic cancer includes more T and N stages that better predict overall survival.

"The most interesting finding is that the new TNM staging system (8th edition) now enables a stratification of the large, 'old' T3 subgroup of patients," Dr. Thilo Welsch from University Hospital Carl Gustav Carus, Technical University Dresden, in Germany, told Reuters Health by email. "In the 7th edition, 96% of the patients with resected pancreatic cancer were classified as pT3. Therefore, the T descriptor was useless as a prognostic discriminator."

"According to the new staging system, this subgroup is now stratified into several different T stages based on the tumor size alone," he said. "Moreover, these different T stages are associated with a significantly different survival."

Dr. Welsch's team validated the eighth edition using data from 256 patients with pancreatic cancer whose median follow-up was 18 months. The cohort's median age was 68.5 years; median tumor size was 32.5 mm.

The researchers focused specifically on the survival stratification of the new T staging.

When they applied the eighth edition retrospectively to these patients, both T and N stage were significant predictors of overall survival, according to the September 21 Annals of Surgery online report.

The 245 patients (96%) whose tumors were classified as T3, according to the seventh-edition system, now were split four different stages based on tumor size: T1b (0.7%), T1c (11.3%), T2 (58.6%), and T3 (21.9%).

The resulting survival of patients with T1-2 versus T3 tumors differed significantly (log-rank test, P=0.0474), independent of nodal and resection status.

"Clinicians and researchers now have a clearly defined T descriptor, which can discriminate different subpopulations of patients with distinct survival prognoses," Dr. Welsch said. "This, in turn, opens the door to detect new, efficient therapeutic targets or therapies."

"Pancreatic cancer is not one homogeneous type of cancer with a dismal prognosis," he concluded. "Instead, we are able to describe a subgroup of patients with a better prognosis (smaller tumors, no or minimal lymphatic spread) and distinct genetic or molecular subtypes. These patients can be identifed by the new TNM stage plus the upcoming genetic subtyping - and might benefit from a tailored multidisciplinary treatment approach."

SOURCE: http://bit.ly/2zbVWDM

Ann Surg 2017.