Pattern of expression of CDX2 in colorectal cancer and its role in prognosis.

Abstract

36 Background: CDX2 (Caudal Homeobox2), a nuclear protein, is essential for the proliferation and development of intestinal epithelial cells and is frequently down-regulated during tumorigenesis. We have evaluated the pattern of expression of CDX2 in all stages of CRC (Colorectal Cancer) and its association with prognosis. Methods: We performed CDX2 staining by immunohistochemistry (IHC) on the available biopsy block of patients of CRC registered with Medical Oncology, JIPMER, from January 2014-January 2018. CDX2 scoring was done in semi-quantitative method. Results: 286 patients were registered during this period, of which only 110 biopsy blocks were available for staining. Of 110 patients, 77 (70%) constituted colon cancer and 33(30%) were rectal cancer. The median age was 54.2 years, 62 (56.4%) being male and 48 (43.6%) female with male to female ratio 1.3:1. In the study cohort, 33(30%) patients had stage II, 30 (27.3%) stage III and 47(42.7%) were stage IV. 73 (66.4%) were positive for CDX2 and 37 (33.4%) were negative. Lack of CDX2 was significantly associated with advanced stage, rectal site, poor grade of differentiation and presence of lympho-vascular invasion (LVSI). With median follow-up of 16 months, PFS (progression free survival) at 2 years was 30% for CDX2 negative compared to 67% for CDX2 positive (P = 0.009), while OS (overall survival) ) at 2 years was 46% for CDX2 negative versus 77% for positive (P = 0.01). Conclusions: Lack of CDX2 is associated with significantly worse PFS and OS, serves as poor prognostic factor in CRC. Lack of CDX2 expression is associated with advanced stage, higher tumor grade and presence of LVSI.