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(2) 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(2) 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.