Prognostic Factors And Their Significance In Nasal NK/T Lymphoma Patients From Mainland China

OBJECTIVE: Nasal Natural killer/T cell (NK/T) lymphoma is a fairly novel disease entityrecognized by the World health Organisation (WHO) classification. It is usually well localized atpresentation but due to resistance to treatment and frequent relapses, it is associated with poorprognosis. Optimal treatment and prognostic factors specific to this disease yet remain to be welldefined. This study was carried out to identify the role of plasma Epstein Barr virus (EBV) DNA,gross tumor volume of primary tumor (GTV-P) and Ki67, among others, as potential prognosticfactors, in nasal NK/T lymphoma.METHODS:51patients with nasal NK/T lymphoma were enrolled in a prospectiveobservational study. Plasma EBV DNA was measured by real time quantitative polymerasechain reaction (RQ-PCR) in51patients and also in15healthy controls. Gross primary tumorvolume (GTV-P) was obtained by a computerized method by means of the treatment planningsystem software. The Ki67for each patient was obtained from their respectiveimmunohistochemistry report of their biopsy sample at presentation. The clinical data about eachpatient was collected from their respective medical files. RESULTS: At presentation,20out of29patients were EBV DNA positive by EBNA-1fragment measurement. All the15controls were negative for EBV DNA. Positive correlationwas present between peak EBV DNA levels and LDH levels (p=0.002). There was a generaldecreasing trend in EBV DNA levels with treatment. The pretreatment EBV DNA levels weresignificantly associated with progression free survival (PFS) on univariate analysis(p=0.04).Patients with high Ki67(≥60%) levels had better PFS (p=0.03) and disease freesurvival (DFS)(p=0.04). No statistically significant difference in overall survival was present inpatients who had a high GTV-P (>31cm3) compared to those who had low GTV-P(p=0.875).Only LDH and number of involved extranodal sites proved to be independentprognostic factors of overall survival on multivariate analysis. However, besides LDH andextranodal sites, ki67was also a significant prognostic factor of PFS.CONCLUSION: EBV DNA levels reflect tumor burden and may be useful for diseasemonitoring. Patients with high Ki67levels had statistically significant longer progression freeand disease free survival probably due to higher sensitivity to treatment as a result of anincreased number of proliferating tumor cells. Gross primary tumor volume did not influence theoverall or progression free survival so that a high GTV-P was not an indicator of poor outcomein our study.