As we all know, telomerase as well as its catalytic subunit hTERT are closely related with the occurrence and development of vast majority of malignant tumors including NPC. Others and we [
12,
16] have shown that telomerase was overexpressed in tumor tissues and tumor cell lines, but not in normal tissues and cells. However, the detection of telomerase activity in tumor tissues of patients who has been diagnosed is not helpful for early diagnosis of tumor. Directly detection of telomerase activity from peripheral blood may play an important role in early diagnosis of patients who has not been diagnosed by the naked eyes and microscopy. Miura et al. [
17] detected hTERT mRNA in peripheral blood of liver cancer patients at early stage and compared it with other serological tumor markers AFP and DCP. Their results showed that serum hTERT mRNA content was higher in liver cancer patients than in patients with chronic liver diseases, but was not related with liver cancer differentiation level. The authors believed that hTERT mRNA in peripheral blood was superior in HCC diagnosis compared with AFP mRNA, AFP and DCP. In addition, they found that serum hTERT mRNA level was significantly different in different tissues and could be used as a new and useful biomarker for cancer. March et al. [
18] also detected plasma hTERT mRNA content in 49 patients with prostate cancer and found plasma hTERT mRNA content was significantly higher in patients with locally advanced lesions than in patients with localized lesions. Thus, it can be used as a non-invasive marker of prostate cancer to differentiate patients with locally advanced disease at molecular level. Kang [
7] and March-Villalba et al. [
19] detected peripheral hTERT mRNA content in patients with gastric and prostate cancer, respectively. Their results showed that hTERT mRNA content in these cancer patients was higher than that in control subjects. They further found that hTERT mRNA content in peripheral blood of patients with gastric and prostate cancer was also closely associated with clinicopathological parameters such as clinical stage, lymph node infiltration range, etc., but not with age and gender. Our study showed for the first time that hTERT mRNA level in peripheral blood of NPC patients was higher than that in control subjects, and was also significantly correlated with patients’ clinical stage, tumor size and lymph node infiltration scope (
P < 0.05). In addition, our results further showed that hTERT mRNA level in peripheral blood of NPC patients at early stage was markedly increased, and this increase became more obvious with severity of tumor stage: the later the stage (for both N and T staging systems) was, the higher the peripheral blood hTERT mRNA content, suggesting that this serological marker could have significance in early diagnosis and clinical staging severity assessment of NPC patients. Our results are consistent with the findings of other scholars on different cancer patients [
6,
20‐
23].
Combined detection of hTERT mRNA with other diagnostic techniques showed a potentially significant value in improving the accuracy of tumor diagnosis and evaluating treatment efficacy of malignant tumors. Ping et al. [
24] found that plasma hTERT mRNA detection combined with PDG-PET/CT can improve the accuracy of tumor diagnosis. Salvatore et al. [
25] reported that for colorectal cancer patients receiving neoadjuvant chemotherapy, peripheral hTERT mRNA can be used to assess the efficacy of chemotherapy. Lu et al. [
26] also showed that peripheral hTERT mRNA level in patients with acute myelogenous leukemia after first chemotherapy decreased to the level of 2.4 ± 2.0 at complete remission from that of 13.5 ± 8.5 before the first treatment (
P < 0.001). Among them, most had normal hTERT mRNA level of 1.2 ± 0.8. Changes in peripheral hTERT mRNA content can also be used to assess the results of tumor surgery. Lu et al. [
26] reported that the content of hTERT mRNA in peripheral blood of patients with laryngeal squamous cell carcinoma after surgery significantly reduced to 8.0 ± 5.7 from that of 11.8 ± 8.3 before surgery (
P = 0.03), suggesting that peripheral hTERT mRNA may become an important indicator for observation of therapeutic responses of cancer patients.
Our results also showed that peripheral hTERT mRNA content of NPC patients at late stage (III and IV) reached 12.68 ± 3.08 before combined therapy, and was reduced to 10.68 ± 2.48 and 3.13 ± 1.69, respectively, after inductive chemotherapy as well as concurrent IMRT and chemotherapy. It can be seen from the results that after inductive chemotherapy, peripheral hTERT mRNA level was decreased slightly in most patients, while after concurrent IMRT and chemotherapy, hTERT mRNA level was significantly decreased in almost all patients. Moreover, after IMRT, hTERT mRNA level was decreased from 5.60 ± 2.33 to 3.43 ± 1.42 in NPC patients at early stages (I and II). All these results suggested that IMRT or concurrent IMRT and chemotherapy had more obvious impacts on peripheral hTERT mRNA level than induction chemotherapy, suggesting that NPC may be more sensitive to radiation therapy. In addition, the action duration of radiation therapy was also longer than that of chemotherapy, leading to more obvious inhibition of telomerase activity and tumor micrometastasis via blood in NPC patients, thereby affecting peripheral hTERT mRNA content. These results in turn support clinical treatment modalities of radiotherapy supplemented by chemotherapy for NPC patients [
27].