Objective Type-I collagen (Col-I) is one of the main macromolecules of the extracellular matrix, and it is involved in the desmoplastic stromal reaction, an indicator of worse prognosis in cases of colorectal cancer (CRC). The purpose of the present study was to investigate Col-I expression in cases of CRC and adenoma and to correlate with the clinical data and the data regarding the lifestyle of the patients. Methods A retrospective study including 22 patients with adenoma and 15 with CRC treated at a coloproctology service. The clinical and lifestyle data were obtained through medical records, and Col-I expression was investigated by immunohistochemistry. Results Women represented most cases of adenoma (63.64%), whereas CRC was found mainly in men (73.33%) (p = 0.0448). Immunoexpression of Col-I showed a basement membrane thickening in areas of lining of epithelium and around the glands in both lesions. The cases of CRC had a quite evident fibrosis process in the stroma. The quantitative analysis demonstrated a higher protein expression in CRCs compared to adenomas (p = 0.0109), as well as in female patients (p = 0.0214), patients aged ≥ 50 years (p = 0.0400), and in those with a positive family history of colorectal disease (p = 0.0292). These results suggested a remodeling of the microenvironment of the tumor in CRC carcinogenesis. Importantly, the clinicopathologic positive correlations showed a plausible link between the patient's profile and the immunohistochemical findings, which indicate a possible form of patient stratification. Conclusion The immunohistochemical analysis encourages the performance of more comprehensive studies to ascertain if our results could be a tool for the diagnosis and monitoring of the patients.