Abstract 853: Prognostic significance of VEGF mRNA in pN0 patients with colorectal cancer

Abstract

Abstract Objectives: Recently, we discovered isolated cytokeratin 20 (CK20) positive cells in pN0 lymph nodes (LN) from patients with colorectal cancer (CRC) and molecular dissection of this micrometastasis pathway is essential for us to understand which metastasis-related mRNA genes are involved. Using tumor metastasis quantitative polymerase chain reaction (QPCR) arrays, vascular endothelial growth factor (VEGF) mRNA has the highest median fold change in CK20 positive pN0 LN when compared to CK20 negative pN0 LN from patients with CRC (AACR Infection and Cancer abstract number B47). In this study, we validate the QPCR array results by measuring VEGF mRNA concentration in an independent set of pN0 patients with CRC and examine the prognostic significance of VEGF mRNA in the same cohort of patients. Materials and Methods: Twenty-nine paraffin-embedded pN0 LN specimens with CK20 positive cells and the same number of specimens without CK20 positive cells from patients with CRC detected by immunostaining were retrospectively retrieved from the Department of Pathology, Queen Elizabeth Hospital, Hong Kong Special Administrative Region. Total RNA was extracted from each sample for the quantification of VEGF mRNA using primers and a Taqman minor groove binder probe which labeled with a carboxyfluorescein reporter dye at the 5′-end and a nonfluorescent quencher at the 3′-end (Applied Biosystems, Foster City, USA). All 58 pN0 patients with CRC were follow-up for 48 months from their respective diagnosis for recurrent or metastatic CRC and a recurrent/metastatic curve was plotted using the median copy number of VEGF mRNA as the cut-off point. Results: The median concentration of VEGF mRNA in CK20 positive pN0 LN (35710 copy numbers, range: 5189-51240 copy numbers) was significantly higher than those in CK20 negative pN0 LN (1654 copy numbers, range: 210-4450 copy numbers) (p < 0.0001, Mann Whitney test). Using the median VEGF mRNA copy number (35710) of 29 CK20 positive pN0 patients with CRC as the cut-off point to plot the recurrent/metastatic curves, the time to recurrence or metastasis was significantly shorter for 14 patients with VEGF mRNA concentration > 35710 copy numbers (median recurrence/metastasis = 29.5 months) than for 15 patients with VEGF mRNA concentration ≤ 35710 copy numbers (p < 0.05, log-rank test). Conclusions: VEGF mRNA concentration is significantly correlated to the time of recurrence/metastasis and it may be able to predict the risk of recurrence/metastasis in pN0 patients with CRC. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 853.