utility of indigenously developed square grid method for evaluation of tumor-stroma ratio and stromal tumor-infiltrating lymphocytes in invasive breast carcinoma: a pilot study

Background objective: invasive breast carcinoma (ibc) is the most commonly diagnosed cancer among women in india. the conventional visual method of evaluation of tumor-stroma ratio (tsr) and stromal tumor-infiltrating lymphocytes (stil) appears to be subjective. the present study aims to evaluate the utility of the indigenously designed square grid method for the evaluation of tumor-stroma ratio and stromal tumor-infiltrating lymphocytes in invasive breast carcinoma by assessing the inter-observer variability.methods: this was a retrospective study conducted at a rural tertiary care referral institute from july 2018 to june 2020. in each case, microphotographs were taken from 10 representative fields in h e-stained sections for evaluating tsr in low-power and stil in high-power. both the parameters were evaluated employing an indigenously designed square grid applied onto microphotographs in the power-point slides by making use of principles of the pythagorean theorem. both parameters were separately evaluated by two pathologists. cohen kappa statistics was the statistical tool used to analyze inter-observer variability.results: thirty cases were analyzed. invasive breast carcinoma of no special type (ibc-nst) was the most common histopathological type (26 cases (86.67%)). for trs evaluation, a kappa value of 0.78 suggested substantial agreement with an agreement of 91.67%. for stil evaluation, a kappa value of 0.51 suggested moderate agreement with an agreement of 88.33%. the p-values were statistically highly significant (p<0.001).conclusion: square grid method is a novel technique for evaluating tsr and stil in invasive breast carcinoma. it can be considered an example of the application of pythagoras’ theorem in pathology.