The Frequency of Circulating Tumour Cells and the Correlation with the Clinical Response to Standard Chemoradiotherapy in Locally Advanced Nasopharyngeal Carcinoma: A Prospective Study

PURPOSE: Circulating tumour cells (CTCs) have been found to correlate with treatment response and prognosis in some cancers; however, such correlations have not been reported in nasopharyngeal carcinoma (NPC). We aimed to determine the relationship between CTCs and the treatment response in NPC. PATIENTS AND METHODS: In this prospective study, we ascertained the karyotype of CTCs and identified a possible correlation between karyotype and treatment response in locally advanced NPC (LANPC). We prospectively collected peripheral blood from LANPC patients. CTCs were measured by negative enrichment with immunofluorescence in situ hybridization (imFISH) and a centromere of chromosome 8 (CEP8) probe. Chromosome 8 was karyotyped in CTCs, which were identified as triploid, tetraploid or multiploid. Patients were then treated with platinum-based induction chemotherapy followed by concurrent chemoradiotherapy. CTCs were measured before and after treatment. RESULTS: We detected CTCs in 27 of 50 (54%) patients, which served as a baseline value. The results were independent of age, smoking history and NPC clinical stage. All of the 27 evaluable enrolled patients with detectable CTCs showed decreases in both total CTCs and CTCs of different ploidies after treatment (P<0.05). Reductions in CTCs were significantly more common in patients with a complete response (CR) than in those with a partial response (PR) (P<0.05). The presence of fewer tetraploid CTCs before treatment had a positive predictive value for a CR to chemoradiotherapy (P<0.05). CTC-positive patients had a shorter PFS after treatment (P=0.03). CONCLUSION: The decrease in CTCs was correlated with therapeutic efficacy in patients with LANPC, and the presence of tetraploid CTCs before treatment is a potential predictive factor for clinical outcomes.