Impact of proliferative indices and tumor suppressor genes on treatment response in marginal zone lymphomas

Abstract

Firstly, increased Ki67 and MUM-1 staining has been associated with worse prognosis in marginal zone B cell lymphomas (MZL). However, ours is the first study to assess the impact of proliferative indices on chemotherapy response. Secondly, loss of p53 and p16 tumor suppressor genes (TSG) has traditionally been associated with cancer progression. The significance of these markers in MZL was investigated. Thirdly, we explored the role of proliferative indices and tumor suppressor genes in identifying MZLs with significant plasmacytic differentiation (PD). Consecutive MZL cases (2006–2008) were identified. Slides were reviewed to confirm the diagnosis; immunohistochemical stains for Ki67, MUM-1, WT-1, p53, and p16 were subsequently performed and graded for percentage staining. Wilcoxon two-sample test and Pearson correlation coefficient were performed. Twenty-nine cases were analyzed. None of the assayed markers were correlated with treatment response. Ki67 and MUM1 expression, however, were correlated with PD (p = 0.0136 and p = 0.0042). A correlation between MUM1 and p16 staining was also seen (p = 0.0006). IHC assay for TSGs, p53 and p16, and proliferative indices (Ki67, MUM1, WT1) is unlikely to predict treatment response in low-grade MZL. Ki67 and MUM1 staining, however, may serve as a useful adjunct in ascribing PD.