Clinical evaluation of circulating tumor cells in locally advanced nasopharyngeal carcinoma: A prospective study.

Abstract

e17523 Background: Circulating tumor cells (CTCs) have been showed to correlate with curative effects and prognosis in many cancers, but there are few data describing the importance of CTCs in nasopharyngeal carcinoma (NPC). Our aim was to prospect the karyotyping of CTCs and the correlation between CTCs and clinical response in patients with locally advanced NPC. Methods: Serum was collected in 82 patients with locally advanced NPC. CTC was measured by negative enrichment with immunostaining of CD45, DAPI and imFISH with the centromere of chromosome 8 probe (CEP8) method. Cells with CD45-/DAPI+/CEP8 ≥3 were defined as positive CTCs and the karyotyping of chromosome 8 in CTCs were identified as triploidy, tetraploidy and multiploidy. Patients were treated with 2 cycles of induction chemotherapy followed by concurrent chemoradiotherapy according to the clinical trial (NCT 02562599). CTC was also measured after each cycle of chemotherapy. Clinial response was classified according to the Response Evaluation Criteria in Solid Tumours (RECIST 1.1) criteria. Results: Positive CTCs were detected in 42 of 82 patients prior to treatment. They were independent with age, sex, smoking and clinical stages. Continuous CTC detection of 30 enrolled patients with positive CTCs showed that the ratio of CTCs and CTCs with different ploidies significantly decreased after therapy (P < 0.05). Although the change was not correlated with clinical response (P = 0.054), the decreases in CTCs count of patients who had complete response (CR) to the treatment were significant (P < 0.05), while the decreases of CTCs count of patients who had partial response (PR) were not (P > 0.05). Further analysis indicated that CR patients had fewer tetraploidy CTCs prior to the therapy than PR patients (P < 0.05). Moreover, tetraploidy CTCs count also indicated a positive prediction value for clinical response to treatment according to maximum likelihood estimation (P = 0.045, 95%CI [1.032,18.060]). Conclusions: The decrease of CTCs is correlated with a better therapeutic efficacy in patients with locally advanced NPC and the number of tetraploidy CTCs before treatment could be used as a predictive factor for clinical outcomes.