Saka, BurcuBalcı, SerdarBaştürk, OlcaBağcı, PelinPostlewait, Lauren Mc LendonMaithel, Shishir KumarKnight, JessicaEl Rayes, BasselKooby, DavidSarmiento, Juan MartinezMuraki, TakashiOliva, IrmaBandyopadhyay, SudeshnaAkkaş, GizemGoodman, MichaelReid, Michelle DianKrasinskas, AlyssaEverett, RhondaAdsay, Nazmi Volkan10.07.20192019-07-1010.07.20192019-07-102016Saka, B., Balcı, S., Baştürk, O., Bağcı, P., Postlewait, L, M. L., Maithel, S. ... Adsay, N. V. (2016). Pancreatic ductal adenocarcinoma is spread to the peripancreatic soft tissue in the majority of resected cases, rendering the AJCC T-stage protocol (7th Edition) inapplicable and Insignificant: A size-based staging system (pT1: ?2, pT2: >2–?4, pT3: >4 cm) is more valid and clinically relevant. Annals of Surgical Oncology, 23(6), 2010-2018. https://dx.doi.org/10.1245/s10434-016-5093-71068-9265https://hdl.handle.net/20.500.12511/941https://dx.doi.org/10.1245/s10434-016-5093-7Background: Most studies have failed to identify any prognostic value of the current T-stage protocol for pancreatic ductal adenocarcinoma (PDAC) by the American Joint Committee on Cancer and the Union for International Cancer Control unless some grouping was performed. Methods: To document the parameters included in this T-stage protocol, 223 consecutive pancreatoduodenectomy specimens with PDAC were processed by a uniform grossing protocol. Results: Peripancreatic soft tissue (PST) involvement, the main pT3 parameter, was found to be inapplicable and irreproducible due to lack of a true capsule in the pancreas and variability in the amount and distribution of adipose tissue. Furthermore, 91 % of the cases showed carcinoma in the adipose tissue, presumably representing the PST, and thus were classified as pT3. An additional 4.5 % were qualified as pT3 due to extension into adjacent sites. The T-stage defined as such was not found to have any correlation with survival (p = 0.4). A revised T-stage protocol was devised that defined pT1 as 2 cm or smaller, pT2 as >2–4 cm, and pT3 as larger than 4 cm. This revised protocol was tested in 757 consecutive PDACs. The median and 3-year survival rates of this size-based protocol were 26, 18, 13 months, and 40 %, 26 %, 20 %, respectively (p < 0.0001). The association between higher T-stage and shorter survival persisted in N0 cases and in multivariate modeling. Analysis of the Surveillance, Epidemiology, and End Results database also confirmed the survival differences (p < 0.0001). Conclusions: This study showed that resected PDACs are already spread to various surfaces of the pancreas, leaving only about 4 % of PDACs to truly qualify as pT1/T2, and that the current T-stage protocol does not have any prognostic correlation. In contrast, as shown previously in many studies, size is an important prognosticator, and a size-based T-stage protocol is more applicable and has prognostic value in PDAC.eninfo:eu-repo/semantics/embargoedAccessPancreatic Ductal AdenocarcinomaSpread to the PeripancreaticSoft TissueMajority of Resected CasesArticle2362010201810.1245/s10434-016-5093-7Q1Q1