Both c-Myc and Ki-67 expression are predictive markers in patients with extranodal NK/T-cell lymphoma, nasal type: a retrospective study in China.

Extranodal natural killer (NK)/T-cell lymphoma, nasal type (ENKTL) is an increasingly recognized disease entity of aggressive tumor progression. The objective of this study was to investigate the clinical and prognostic significance of c-Myc and Ki-67 expression in ENKTL. Immunohistochemistry for c-Myc and Ki-67 was performed on tissue sections from 53 patients diagnosed with ENKTL, and their correlation with clinicopathologic variables was assessed. We also made a comparison between c-Myc positive and negative ENKTL on proliferation index (PI); and analyzed relationship between expression of c-Myc and Ki-67 index. The survival was analyzed by Kaplan-Meier product-limit method. Positive expression of c-Myc was shown in 64.2% of the patients, and high expression of Ki-67 was found in 66%. The PI in c-Myc-positive tumor cell was significantly higher than that in c-Myc-negative ones (P=0.005). The positive correlation between c-Myc expression and Ki-67 index was also found (r=0.454, P=0.001). Patients of c-Myc expression were shown to be associated with unfavorable overall survival (OS) and decreased progression free survival (PFS) (P=0.000 and 0.013, respectively). High expression of Ki-67 was also shown to be correlated with worse OS and PFS (P=0.014 and 0.016, respectively). And patients expression of c-Myc+/Ki-67 high had the worst OS and PFS (P=0.002 and 0.027, respectively). c-Myc may play an important role in the carcinogenesis of NK/T cell lymphoma by promoting cell proliferation. Both c-Myc expression and Ki-67 high expression in ENKTL patients may be valuable indicators for predicting the survival of ENKTL patients.