659P - PIK3CA mutations up-regulate Akt expression and confer aggressive tumor biology in gastric cancer

Date 08 October 2016
Event ESMO 2016 Congress
Session Poster Display
Topics Gastric Cancer
Presenter Keun-Wook Lee
Citation Annals of Oncology (2016) 27 (6): 207-242. 10.1093/annonc/mdw371
Authors K. Lee1, J. Kim2, J.W. Kim2, H.S. Lee3
  • 1Internal Medicine, Seoul National University Bundang Hospital, Seoul National University College of Medicine, 13620 - Seongnam/KR
  • 2Department Of Internal Medicine, Seoul National University Bundang Hospital, 13620 - Seongnam/KR
  • 3Department Of Pathology, Seoul National University Bundang Hospital, Seongnam/KR

Abstract

Background

PIK3CA mutations are frequently observed in gastric cancer (GC). However, their pathologic and clinical implications have not been well understood yet.

Methods

Clinical and pathological data of patients with stage I-IV GC who underwent gastrectomy between May 2003 and December 2005 were retrospectively analyzed according to their PIK3CA mutation status using real-time polymerase chain reaction.

Results

A total of 302 patients (male, 202) were included and the median age of patients was 61 years (range, 29-89). PIK3CA mutations were detected in 40 patients (13%). Compared with PIK3CA wild-type tumors, cytoplasmic expression of Akt was significantly increased in PIK3CA mutant tumors [immunohistochemstry 3 + : 17% (mutant) vs. 2% (wild type); p = 0.001]. PIK3CA mutant tumors were more likely to be located in the upper third of stomach (37% vs. 18%; p = 0.021) and presented with more advanced T stage (pT4: 53% vs. 33%; p = 0.018). PIK3CA mutant tumors were significantly associated with poorly differentiated histology (73% vs. 46%; p = 0.018), and increased lymphatic (93% vs. 75%; p = 0.015), vascular (35% vs. 16%; p = 0.005), and perineural invasion (73% vs. 54%; p = 0.026). In addition, these tumors exhibited significantly more lymphocyte and neutrophil infiltration in stroma (p 

Conclusions

PIK3CA mutations up-regulate Akt expression and seem to confer aggressive tumor biology in GC. These data suggest that PIK3CA-mutated GC may be a distinct disease entity. However, the existence of PIK3CA mutation was not associated with poor prognosis in GC patients receiving gastrectomy.

Clinical trial identification

Legal entity responsible for the study

None

Funding

This study was partially supported by research grants from the Seoul National University Bundang Hospital Research Fund (02-2015-009).

Disclosure

All authors have declared no conflicts of interest.