Published online Jun 9, 2020. doi: 10.4292/wjgpt.v11.i2.25
Peer-review started: December 30, 2019
First decision: February 24, 2020
Revised: March 26, 2020
Accepted: May 12, 2020
Article in press: May 12, 2020
Published online: June 9, 2020
Pancreatic ductal adenocarcinoma (PDAC) is one of the leading causes of cancer related death worldwide. For the purpose of better risk stratification and clinical management, the American Joint Committee on Cancer (AJCC) published the eighth edition staging manual for pancreatic cancer that has introduced significant changes for both tumor (T) staging and nodal (N) staging. Notably majority of the validation studies were focused on PDAC in the head of pancreas, and the resected distal pancreatic adenocarcinoma was likely underrepresented due to its clinical rarity. Whether the AJCC 8th edition staging manual provides equal risk stratification for both invasive intraductal papillary mucinous neoplasm (IPMN) and non-IPMN associated PDAC is also unclear.
It’s important to investigate whether the new AJCC staging system provides risk stratification in patients with distal pancreatic cancers. It’s also important to investigate the clinical behavior and risk stratification for invasive IPMN and non-IPMN associated PDAC.
This study aims to validate the AJCC 8th edition staging manual in distal PDAC.
Clinicopathological data of resected distal PDAC cases were retrieved. All cases were re-staged based on the AJCC 7th and 8th edition, respectively. Categorical variables were compared with Fisher’s exact test. Progression-free survival (PFS) and overall survival (OS) were evaluated through Kaplan-Meier curves and univariate/multivariate analyses.
T and N staging of both 7th and 8th edition sufficiently stratify PFS and OS in the entire cohort, although dividing into N1 and N2 according to the 8th edition does not show additional stratification. For PDAC arising in IPMN, T staging of the 7th edition and N1/N2 staging of the 8th edition appear to further stratify PFS and OS. For PDAC without an IPMN component, T staging from both versions fails to stratify PFS and OS.
The AJCC 8th edition TNM staging system provides even distribution for the T staging, however, it does not provide better risk stratification than previous staging system for distal pancreatic cancer. There is significant difference of clinical outcome and risk stratification between invasive IPMN and non-IPMN associated PDAC.
Tumor location and subtype are important factors to be considered in future revisions of the AJCC staging system for pancreatic cancer.