Abstract 3365: High infiltration of mast cells predicts worse outcome following resection of colorectal liver metastases
Authors: Suzuki Shinsuke , Ichikawa Yasushi , Nakagawa Kazuya , Kumamoto Takafumi , Mori Ryutaro , Matsuyama Ryusei , Takeda Kazuhisa , Ota Mitsuyoshi , Tanaka Kuniya , Endo Itaru 
Published: August 2015

Abstract
Background.
Tumor infiltrating mast cells (MCs) are considered a primary host immune response against cancer. From some reports, their roles are not determined yet and vary with the type of cancer. There was no report about tumor infiltrating MCs in colorectal liver metastases (CRLM). Aim of this study is to determine whether peritumoral MCs infiltration of CRLM become a predictive factor of survival after curative resection of CRLM.
Methods. A total of 135 patients who underwent potentially curative resection for CRLM between 2001 and 2010 were included in our retrospective study. Expression of tryptase, MAC387, CD83, and CD31, which are markers for MCs, macrophages, mature dendritic cells, and vascular endothelial cells, respectively, was determined via immunohistochemistry of resected tumor specimens. The different types of immune cells in the 3 most abundant peritumoral areas and normal liver areas were counted, and the each cell number was utilized to predict a good prognosis. “Peritumoral” was defined as the division between normal liver tissue and the tumor. The cut-off point of each immune cell number was calculated to select a group of good prognosis after liver resection by using the Youden index from the ROC curve. Using these cut-off points, 135 patients were classified into 2 groups and statistic difference of prognosis was calculated by Kaplan-Meier analysis and the log rank test, and statistic difference of clinic-pathological feature was calculated by chi square test and cox proportional hazard regression. This study was approved by the Yokohama City University Ethics Committee.
Results.
Cancer-specific survival (CSS) at 1, 3, and 5 years were 91.0%, 62.4%, and 37.4%, respectively. The cut-off points were fixed 26 of MCs, 176 of Mϕs, and 17 of DCs. Only the cut-off point of MCs classified 2 groups which showed significantly different prognosis. 54% (73 of 135) of patients were classified in the high MC group. Five-year disease free survival (DFS) of the high MC group and the low MC group was 1.6% and 42.6%, respectively (P&lt;0.001) and CSS of the 2 was 38.1% and 55.6%, respectively (P&lt;0.01). In the clinicopathological feature, only the peritumoral vessel density showed significant difference, significantly higher in the high MC group. Multivariate analyses indicated that hypoalbuminemia and high peritumoral MC infiltration were significant predictors of unfavorable CSS.
Conclusion. High peritumoral MC infiltration predicts poor prognosis in patients after resection of liver metastases of colorectal cancer. High MC infiltration might be related with peritumoral neovascularization.
Citation Format: Shinsuke Suzuki, Yasushi Ichikawa, Kazuya Nakagawa, Takafumi Kumamoto, Ryutaro Mori, Ryusei Matsuyama, Kazuhisa Takeda, Mitsuyoshi Ota, Kuniya Tanaka, Itaru Endo. High infiltration of mast cells predicts worse outcome following resection of colorectal liver metastases. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 3365. doi:10.1158/1538-7445.AM2015-3365