Correlation of French Federation of Cancer Centres Sarcoma Group (FNCLCC) Grade With Ki-67 Proliferation Index in Malignant Soft Tissue Sarcomas

Background: Soft tissue sarcomas are rare malignant tumours comprising diverse histological subtypes with variable biological behaviour. Histological grading using the French Federation of Cancer Centres Sarcoma Group (FNCLCC) system is widely applied for prognostic stratification. Immunohistochemical advances have introduced proliferative markers such as Ki-67 as potential adjuncts to conventional grading. Objective: This study aimed to determine the correlation between the Ki-67 proliferation index and histological grade of soft tissue sarcomas using the FNCLCC grading system. Methods: This retrospective observational study included 49 histologically confirmed malignant soft tissue sarcomas evaluated at a tertiary care centre over a one-year period. Eligible incisional and excisional biopsy specimens were assessed histopathologically and graded using the FNCLCC grading system. Ki-67 immunohistochemistry was performed, and the proliferation index was categorised as low, intermediate, or high. The association between FNCLCC grade and Ki-67 proliferation index was analysed using the chi-square test, with p < 0.05 considered statistically significant. Results: The mean age was 30.6 years with male predominance (male: female = 1.7:1). The lower extremity was the most common site, and Ewing’s sarcoma was the predominant subtype (22.4%). Tumours were classified as Grade 1 (14.3%), Grade 2 (42.9%), and Grade 3 (42.9%). A significant association was observed between FNCLCC grade and Ki-67 proliferation index (p < 0.001). Conclusion: The Ki-67 proliferation index showed a significant correlation with FNCLCC histological grade in malignant soft tissue sarcomas and may be considered an adjunctive histopathological marker of proliferative activity. However, larger prospective studies with subtype-stratified analysis and clinical outcome correlation are necessary to determine its independent prognostic relevance and practical applicability.