Efficiency of High Cumulative Cisplatin Dose in High- and Low-risk Patients with Locoregionally Advanced Nasopharyngeal Carcinoma

Background: The optimal cumulative cisplatin dose (CCD) during radiation therapy for locoregionally advanced nasopharyngeal carcinoma (LA-NPC) patients receiving induction chemotherapy (IC) plus CCRT remains controversial. This study aimed to explore the treatment efficiency of CCD for high-and low-risk patients with LA-NPC.

Methods: Data from 472 LA-NPC patients diagnosed from 2014 to 2018 and treated with IC plus CCRT were reviewed. After propensity score matching, the therapeutic effects of a CCD > 200 and CCD ≤ 200 mg/m were evaluated comparatively. Five factors selected by multivariate analysis were incorporated to develop a nomogram. Subgroup analysis was conducted to explore the role of different CCDs in nomogram-defined high- and low-risk groups. Additionally, acute toxicities were evaluated comparatively between the high- and low-CCD groups.

Results: After matching, there was no difference between different CCD groups for all patients in terms of 3-year overall survival (OS), distant metastasis-free survival (DMFS), locoregional recurrence-free survival (LRRFS), or progression-free survival (PFS). A nomogram was built by integrating pretreatment EBV DNA, clinical stage, and post-IC EBV DNA, post-IC primary gross tumor and lymph node volumes obtained a C-index of 0.674. The high-risk group determined by the nomogram had poorer 3-year PFS, OS, DMFS, and LRRFS than the low-risk group. A total of CCD > 200 mg/m increased the survival rates of 3-year PFS and DMFS (PFS: 72.5% vs. 54.4%, p = 0.012; DMFS: 81.9% vs. 61.5%, p = 0.014) in the high-risk group but not in the low-risk group. Moreover, the high CCD increased treatment-related acute toxicities.

Conclusions: A high CCD was associated with better 3-year PFS and DMFS rates than a low dose for high-risk patients but could not produce a survival benefit for low-risk patients.