Background & objective: Radiotherapy is the fundamental treatment for the patients with nasopharyngeal carcinoma (NPC). Altered fraction radiotherapy and chemotherapy have become a part of combined regimes for advanced disease judged by clinicopathological criteria. However, the known prognostic factors reveal a wide range of treatment outcomes with NPC. This study was designed to investigate whether the deoxyribonucleic acid (DNA) content or proliferative indices (PIs) of the tumors in NPC patients detected with flow cytometry (FCM) could be an additional prognostic reference.
Methods: Two hundred and five cases of paraffin-embedded archival NPC biopsies obtained from the patients treated from 1994 to 1995 were tested for the analysis of DNA ploidy, and proliferative indices including S-phase fraction(SPF), G2/M-phase fraction (G2/MF), and proliferative fraction (PF). DNA ploidy and PIs of tumors were correlated to the clinical parameters and prognosis of the patients.
Results: Of the 205 tested cases, 117 tumor biopsies were satisfied the guideline criteria of the DNA Cytometry Consensus Conference. Thirty-five tumors (30%) were aneuploid (AN) and eighty-two (70%) were DNA diploid (DP). DNA ploidy and PIs were not significantly associated with age, sex, pathological classification, T/N classification, and clinical stage. AN tumors had a significantly higher SPF and PF than the DP tumors did (P = 0.023, P = 0.012, respectively). There was a significant difference in 5-year relapse-free-survival (RFS) between the patients with DP and those with AN (62% versus 43%, P = 0.035). There was a significant difference in 5-year RFS among low, middle, and high SPF and PF groups(81% versus 61% versus 21%, 77% versus 62% versus 33%, respectively) (P = 0.000, P = 0.048, respectively). There were no significant differences in 5-year RFS among the low, middle, and high G2/MF groups (55% versus 58% versus 54%, P = 0.8617).
Conclusion: DNA ploidy, SPF, and PF could be predictors of prognosis for NPC patients. Thus, determination of these indices can be used as an additional reference for clinicians to identify a poor prognostic NPC individual together with clinic pathological parameters.