Fibrosis and Mast Cells in Colorectal Lesions: Significance in Adenoma-Colorectal Cancer Sequence and Association with Diet

Purpose: Adenoma is the most common benign neoplasm with potential to progress into colorectal cancer (CRC), a disease responsible for high rates of mortality. However, it is not possible yet to establish which lesions will evolve into CRC. We aimed to investigate the intrinsic factors, diet profile, and microenvironment as factors involved in adenoma-CRC progression.

Methods: We evaluated nutritional profile and microscopic features. Adenomas and CRC lesions were stained with Mallory's trichrome to reveal fibrosis and Alcian blue to identify mast cells.

Results: A total of 143 patients was selected, 66 % diagnosed with normal mucosa, 28.4 % with benign lesion, and 5.6 % with CRC. A higher frequency of lesions was associated with patients older than 50 years (26.57 %) and women (18.18 %), but men were more likely to develop CRC. Regarding microscopic aspects, epithelium-connective tissue interface with disorganization feature was significantly higher in CRC when compared to adenoma (P = 0.0007). A greater fibrosis around vessels was also observed in CRC (P = 0.01). The statistical analysis indicated a significant correlation between mast cell population and patients older than 50 years (P < 0.01), male (P < 0.01), with right colon lesion (P < 0.05) and CRC. Low consumption of leafy greens (P < 0.001) and carotenoids (P < 0.01) and elevated consumption of red meat (P < 0.001) were associated with a high density of mast cells.

Conclusions: An association between clinical, diet profile, and microscopic features in colorectal lesions was observed, with a progressive change in the microenvironment during adenoma-CRC sequence.