| Research background and purpose:Over 70% of NPC patients were locally advanced nasopharyngeal carcinoma,and the most dominant mode of failure is local recurrence and distant metastasis.The 5-year local recurrence-free survival rate in T1-2 is over 90%,but only about 80% in T3-4.Currently,NCCN and CSCO recommend the use of induction chemotherapy combined with concurrent chemoradiotherapy for LANPC.Low-dose fractionated radiotherapy(LDFRT),which is <100c Gy,induces enhanced cell killing by the hyper-radiation sensitivity phenomenon and potentiates effects of chemotherapy,However,few relevant clinical studies have been reported.Studies in locally advanced cervical cancer have found that the ORR after induction chemotherapy combined with LDFRT was up to 100%(40% CR,60% PR),and the local control rate was up to 84%.A single arm study found the ORR of primary site was improved to 90% for head and neck squamous carcinoma patients treated with LDFRT and NACT.However,another study showed there was no significant difference between LDFRT and control group for LANPC patients.Therefore,this study aimed to explore the potential efficacy and safety of LDRT combined with induction chemotherapy in patients with T3-4 NPC.Methods:Patients with T3-4 nasopharyngeal squamous cell carcinoma(UICC / AJCC 8th edition),aged 18-70 years,with ECOG score of 0-1,normal blood routine and liver and kidney function.They were divided into experimental and control groups according to the random number table.All patients received 3 cycles of induction chemotherapy with docetaxel(75 mg / m2)and cisplatin(80 mg / m2)on days 1,22,and 43,followed by cisplatin-based concurrent chemoradiotherapy.The experimental group performed lowdose fractionated radiotherapy for primary site on days 1 and 2 of induction chemotherapy,0.5Gy twice daily,with an interval of 4-6 hours for a total of 2 days.Efficacy evaluation and toxic side effects were assessed using RECIST1.1 and CTCAE 5.0.SPSS was used to compare the recent efficacy,tumor volume reduction rate and safety between the two groups.Result:From February 2022 to December 2022,62 patients were enrolled,including 31 patients in the LDRT group and 31 patients in the control group.The median age of all patients was 51.5years(range:18-69 years).Tumor stages T3 and T4 were 38.71%、61.29% and 45.16%、54.84% in the LDRT and control groups(P=0.793).During the induction chemotherapy,for primary site,the ORR was significantly higher in the LDRT group than in the control group(93.55% vs 74.19%,P=0.038),and the median volume reduction rate in the LDRT group was 68.54%,while the control group was only 40.45%(P<0.05).The ORR of lymph nodes in the LDRT group increased compared with the control group(96.77% vs 83.87%,P=0.195)with no statistical difference.The median reduction rate of lymph nodes in the LDRT group and control group were 86.28% vs 56%(P<0.05),After the completion of the concurrent chemoradiation therapy,the median volume reduction rate of primary site had an increased tendency in LDRT group(94.25%vs 89.34%,P=0.192),but the ORR had no statistical significance(LDRT group:CR:41.94%;PR:58.06%;control group: CR:35.48%;PR:64.52%).All patients were well tolerated during the induction chemotherapy,no grade 5 adverse events occurred,the most common grade 3-4 adverse effects were leukopenia,with 16.7% vs 20%(P=0.786)in LDRT and controls.Conclusion:low-dose fractionated radiotherapy combined with induction chemotherapy could obviously improve the median volume reduction rate and objective response rate of primary site for T3-4 nasopharyngeal carcinoma patients during induction chemotherapy.This novel treatment model could be a promising strategy to improve local control and needed to be confirmed in future practice. |
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