The role of Ki-67 in the prognostic evaluation of multiple myeloma / 白血病·淋巴瘤

ABSTRACT

Objective:To investigate the expression level of Ki-67 in the bone marrow biopsy of newly diagnosed MM patients, and its relationship with clinical efficacy and prognosis.Methods:Bone marrow pathological samples of 124 newly diagnosed MM patients in Jiangsu Province Hospital from January 2012 to June 2017 were collected. The expression level of Ki-67 in myeloma cells was detected by using immunohistochemistry. X-tile software was applied to find a cutoff of Ki-67. The patients were divided into the high Ki-67 expression group and the low Ki-67 expression group, and the clinical characteristics, therapeutic efficacy and survival of both groups were compared. Chi-square test or Fisher's exact test was used to analyze the counting data. Kaplan-Meier method was applied to make survival anlaysis. Cox regression model was used for univariate prognostic analysis and multivariate prognostic analysis.Results:A total of 124 newly diagnosed MM patients were enrolled with median follow-up of 36 months. The proportion of the positive myeloma cells in abnormal plasmocytes was used to quantize the expression level of Ki-67. Using a cutoff of 20%, these cases could be divided into two groups; the proportion of positive cells was lower than 20% (the low Ki-67 expression group) and the proportion of positive cells was 20% or above (the high Ki-67 expression group). There were 27 cases (21.7%) in the high expression group and 97 cases (78.2%) in the low expression group. There were no statistically significant differences in the clinical characteristics and treatment regimens (all P > 0.05). The overall remission rate (ORR) of patients in the high Ki-67 expression group was lower than that of patients in the low Ki-67 expression group [59.3% (16/27) vs. 83.5% (81/97)], and the difference was statistically significant (χ 2 = 7.290, P = 0.007). The percentage of patients who achieved very good partial remission (VGPR) and complete remission in the high Ki-67 expression group was lower than that of those in the low Ki-67 expression group [33.3% (9/27) vs. 66.0% (64/97)], and the difference was statistically significant (χ 2 = 9.297, P = 0.002). There were statistically significant differences in the median progression free survival (PFS) time (12.0 months vs. 31.0 months, P < 0.01) and 3-year PFS rate (10% vs. 37%, P = 0.002). The median overall survival (OS) time was 39.0 months and 56.5 months in the high and low Ki-67 expression groups, respectively ( P = 0.003). The multivariate analysis showed that high Ki-67 expression was an independent affecting factor for PFS ( HR = 3.592, 95% CI 1.921-6.719, P < 0.01) and OS ( HR = 3.511, 95% CI 1.537-8.022, P = 0.003). Conclusions:High expression of Ki-67 is an independent poor prognostic factor affecting therapeutic effect and survival for newly diagnosed MM patients.