DNA content of nasopharyngeal carcinoma: an independent prognostic indicator

The purpose of this study was to examine whether tumor DNA content correlated with prognosis in nasopharyngeal carcinoma (NPC). DNA flow-cytometric analysis in fresh specimens of nasopharyngeal biopsy from 123 patients with clinical suspicion of NPC was collected initially. Histopathologic study and successful flow-cytometric analysis had 28 lymphoid hyperplasias and 87 NPCs. Seventeen NPC patients were treated elsewhere and were excluded. A total of 98 patients, including 28 lymphoid hyperplasias and 70 NPCs, formed the materials of this study. There were 34 (49%) diploid and 36 (51%) aneuploid in NPC patients. No lymphoid hyperplasias were aneuploid. The mean of S-phase fraction was higher in NPC than in lymphoid hyperplasia (P < .001), indicating higher cellular activity in NPC. DNA content failed to associate with age, gender, pathology, distant metastasis, and stage, indicating that DNA content was an independent prognostic indicator and possibly a clinical parameter. The log-rank test of overall survival curves was significant for stage (P = .002) and DNA ploidy (P = .042); it was almost significant for S-phase fraction (P = .057). Because the follow-up duration was not long enough, univariate and multivariate analysis were not significant for stage, ploidy, and S-phase fraction, except for distant metastasis. It is also most likely colinearity of clinical stage and distant metastasis that explained why clinical stage could not show significance in prognosis. Interestingly, the DNA content appeared to be a potential prognostic parameter in overall survival, although it was not statistically significant (P = .052). Our data suggested that NPC patients with aneuploid DNA and high S-phase fraction tend to have poor prognosis and should be treated more aggressively, even in the early stage of the disease.