Prognostic Value of the Ki67 Proliferation Index, CD10 and MUM1 in Follicular Lymphoma

Background/Purpose: Follicular lymphoma (FL) is an indolent lymphoma and is associated with a long survival time. However, there are patients who had an early progression after standard therapy. Our aim was to analyze the prognostic value of Ki67, CD10 and MUM1 expression in FL. Methods: Immunohistochemical staining for Ki67, CD10 and MUM1 was performed on formalin-fixed paraffin-embedded biopsy tissues from 27 patients with FL. Patients were grouped according to the levels of the Ki67 proliferation index (PI). Survival times were analyzed and the cut-off value for Ki67 PI was determined. The patients were also divided into groups according to the presence of CD10, MUM1and MUM1 positive/CD10 negative. Results: Ki-67 PI levels were as follows: ≤ 20% in 14 patients, 21-40% in 6 patients, 41-60% in 4 patients, > 60% in 3 patients. A cut-off value of 60% revealed significantly different survival rates. OS, PFS in the Ki67 > 60% group decreased significantly for 5 years, and the difference was statistically significant (37.5% vs. 100%, p = 0.000; 0% vs. 66.7%, p = 0.016; respectively). The CD10 negative group had a less favorable outcome than the positive group in the OS rate at 5 years (72% vs. 100%, p = 0.049) and the PFS rate at 5 years (25.3% vs. 72.6%, p = 0.017). OS and PFS in the group with MUM1 positive/CD10 negative decreased significantly for 5 years than in the group without MUM1 positive/CD10 negative (4.7% vs. 100%, p = 0.002; 0% vs. 66.4%, p = 0.006; respectively). Conclusion: Ki67 > 60%, CD10 negative, MUM1 positive/ CD10 negative are poor prognostic factors in FL.