title: Prognostic relevance of the Ki-67 proliferation index in patients with mantle cell lymphoma.
abstract: BACKGROUND
  A high Ki-67 proliferation index (PI) in neoplastic cells is associated with poor survival in mantle cell lymphoma (MCL). We aimed to determine the cut-off values for the Ki-67 PI as a prognostic factor in MCL according to bone marrow findings.
  
  
  METHODS
  Immunohistochemical (IHC) staining for Ki-67 was performed on formalin-fixed paraffin-embedded biopsy tissues from 56 patients with MCL. Patients were grouped based on their Ki-67 PI values. Survival analyses were carried out and the cut-off value for the Ki-67 PI was determined.
  
  
  RESULTS
  Of the 56 patients, 39 (69.6%) showed bone marrow involvement of MCL; 21 of these patients had leukemic manifestations at the time of diagnosis. The results of the Ki-67 IHC staining were as follows: ≤10% in 22 patients, 11-20% in 14 patients, 21-30% in 3 patients, 31-40% in 4 patients, 41-50% in 4 patients, and >50% in 9 patients. A cut-off value of 20% revealed significantly different survival rates with mean survival times of 69.8 months (Ki-67 PI≤20%) and 47.9 months (Ki-67 PI>20%), irrespective of bone marrow findings (P=0.034). Clinical outcomes did not differ, regardless of bone marrow findings. However, in cases with bone marrow involvement, the Ki-67 cut-off value of 30% for overall survival was required to yield statistical significance (P=0.033).
  
  
  CONCLUSIONS
  The 20% cut-off value for the Ki-67 PI was clinically meaningful, regardless of bone marrow involvement of MCL. For patients with bone marrow involvement, the statistically significant cut-off value increased to 30%.
authors.affiliation: Department of Laboratory Medicine, University of Ulsan College of Medicine and Asan Medical Center, Seoul, Korea.; Department of Laboratory Medicine, Ewha Womans University School of Medicine, Seoul, Korea.
authors.forename: Tae-Dong
authors.initials: TD
authors.lastname: Jeong
authors.affiliation: Department of Laboratory Medicine, University of Ulsan College of Medicine and Asan Medical Center, Seoul, Korea.
authors.forename: Hyun-Sook
authors.initials: HS
authors.lastname: Chi
authors.affiliation: Department of Laboratory Medicine, University of Ulsan College of Medicine and Asan Medical Center, Seoul, Korea.
authors.forename: Min-Sun
authors.initials: MS
authors.lastname: Kim
authors.affiliation: Department of Laboratory Medicine, University of Ulsan College of Medicine and Asan Medical Center, Seoul, Korea.
authors.forename: Seongsoo
authors.initials: S
authors.lastname: Jang
authors.affiliation: Department of Laboratory Medicine, University of Ulsan College of Medicine and Asan Medical Center, Seoul, Korea.
authors.forename: Chan-Jeoung
authors.initials: CJ
authors.lastname: Park
authors.affiliation: Department of Pathology, University of Ulsan College of Medicine and Asan Medical Center, Seoul, Korea.
authors.forename: Joo Ryung
authors.initials: JR
authors.lastname: Huh
keywords: Bone marrow; Ki-67 proliferation index; Mantle cell lymphoma; Prognosis