Background: Our aim was to explore relevance of the proportion between
neoplastic cell component and tumor-associated stroma in order to assess its
association with confirmed aggressive phenotypes of right/left colon and
rectum cancers in a large series of patients. Methods: The quantification of
stroma component was performed in patients diagnosed with colorectal
adenocarcinoma who underwent surgical resection. The analyzed variables were
age, gender, anatomical/pathological features, and tumor-stroma proportion.
Tumor-stroma proportion was estimated based on slides used in routine
pathology for determination of T status and was described as low, with a
stromal percentage ?50% or high, with a stromal percentage >50%. The
tumor-stroma proportion was estimated by two observers, and the
inter-observer agreement was assessed. Results: The sample included 390
colorectal adenocarcinoma patients. Stroma-rich tumors were observed in
53.3% of cases. Well-differentiated tumors had the lowest stromal
proportions (p = 0.028). Stroma-poor tumors showed less depth of invasion
(p<0.001). High stromal content was observed in association with tumor
budding, perineural, angiolymphatic, and lymph node involvement, and distant
metastasis (p?0.001). Colorectal adenocarcinoma without lymph node or
distant metastasis involvement had lower stromal proportion, while
metastatic ones exhibited high stromal content (p <0.001). The inter-rater
reliability (concordance) between the estimations of pathologists for
tumor-stroma proportions was high (?=0.746). Conclusion: The tumorstroma
proportion in colorectal adenocarcinoma was associated with adverse
prognostic factors, reflecting the stage of the disease. Stroma-rich tumors
showed a significant correlation with advancement of the disease and its
aggressiveness. Due to its availability tumor-stroma proportion evaluation
has high application potential and can complement current staging system for
colorectal adenocarcinoma.