Role of fibrotic cancer stroma in rectal carcinoma: An immunomorphological assessment

Background: The aim of the study is to evaluate the role of fibrotic cancer stromal response and tumor budding in ectal adenocarcinoma development and progression. Materials and Methods: Fibrotic cancer stroma was classified into three distinct histological categories, i.e. mature, intermediate, and immature. The number of tumor-budding foci was counted in the low-power field (×10), and 0–5, 5–9 and ≥10 tumor buds were scored as I, II, and III, respectively. All histological and immunohistochemical assessments were made at the invasive front of the tumor. The distribution of T lymphocytes and myofibroblasts was assessed by immunohistochemical reactivity for the cluster of differentiation 3 and anti-smooth muscle antibody actin, respectively. Results: Among 25 cases of rectal carcinoma, 60% (15 cases) of patients had mature fibrotic cancer stroma, whereas 28% (7 cases) of patients had intermediate stroma and 12% (3 cases) of patients had immature stroma. The cancer-specific 5-year survival rate in the groups with mature stroma, intermediate stroma, and immature stroma was 53.34%, 42.8%, and 33.34%, respectively. There was a statistically significant correlation between the category of fibrotic cancer stroma and the tumor budding. Further, on immunohistochemical analysis and counting, the average number of T-cells was 302/400 μm diameter field in the region of mature fibrotic stroma, in comparison with 197/400 μm and 92/400 μm in the intermediate and immature fibrotic stroma, respectively (unpaired t-test with P < 0.05). Myofibroblasts were observed in 20% of tumors with mature fibrotic stroma compared with 65% in the intermediate fibrotic stroma and 100% of the tumors with immature fibrotic cancer stroma. Conclusions: The histological classification of fibrotic cancer stroma highlights the role of the stromal response with respect to host immune reaction and behavior in rectal adenocarcinoma and acts as a useful tool for predicting patient prognosis and outcome.