Immunohistochemical Expression Profile of SATB2 in Colorectal Adenocarcinoma and Association with Clinicopathological Parameters

Introduction: Colorectal carcinoma is the third most common cancer worldwide. Several clinicopathological parameters act as prognostic factors in colorectal carcinoma, but only a few are helpful in predicting the treatment outcome. Therefore, there is a need for better prognostic markers which also aids in assessing treatment benefits in colorectal carcinoma patients. Special AT Rich Sequence Binding Protein 2 (SATB2) is a highly specific marker for colorectal tissue. Decreased expression of SATB2 is also associated with poor prognosis in colorectal carcinoma.

Aim: To analyse the histomorphology, immunohistochemical expression profile of SATB2 and association with clinicopathological parameters in colorectal adenocarcinoma.

Materials and Methods: The cross-sectional study included 84 cases of colorectal carcinoma received in the Department of Pathology, SRM Medical College Hospital and Research Centre, Kattankulathur, Chennai, Tamil Nadu, India, in the period between April 2021 to September 2022. Both biopsy and resected specimens were included in the study. Relevant clinical data was collected. Histological diagnosis, grading and staging of the tumour was done using Haematoxylin and Eosin (H&E) slides as described and tabulated. Immunohistochemistry (IHC) for SATB2 was done and expression profile compared with the clinicopathological parameters to assess prognostic significance. Data was analysed using software-Statistical Package for Social Sciences (SPSS, version 23.0).

Results: Out of the 84 cases, 42 were biopsy and 42 were resected specimens. Mean age of the patients in the study was 57.9 years. Patients were predominantly males (n=51, 60.7%) with a male:female ratio of 1.54:1. Of the 84 cases, 40.5% (n=34) had tumour located in the rectum. Majority of the cases were moderately differentiated adenocarcinoma (n=48, 57.1%). Predominantly, stage III tumours (n=33, 39.3%) were noted. Out of the tumours showing decreased expression of SATB2, 55% (n=22) were left-sided tumours, metastasis was seen in 60% (n=24 cases), 37.5% of cases (n=9) showed lymphovascular invasion, and 55% (n=22) had a stage III tumour.

Conclusion: The present study results indicate that a decrease in SATB2 expression is associated with presence of lymphovascular invasion, perineural invasion, regional and distant metastasis and a higher pathological stage which signifies poor prognosis in colorectal carcinoma. These aid the physician for risk stratification of patients and enable personalised treatment choices including adjuvant chemotherapy in high-risk groups.