The prognostic value of the early tumor response to first-line chemotherapy remains unknown in metastatic nasopharyngeal carcinoma (mNPC). The aim of this study was to explore the association between early tumor response (response at 6 weeks) and survival outcomes and to assess the relationship between best (response at 18 weeks) and early tumor response.
A total of 433 mNPC patients with measurable lesions, who received first line chemotherapy between 2005 and 2016 were enrolled in this study. Response was assessed at completion of 6 weeks and 18 weeks of chemotherapy using RECIST 1.1. To estimate in an unbiased way, the landmark method was used in this study. Log-rank test and Cox regression were used to analyze survival data. The correlation between early tumor response and best tumor response was measured by Kappa agreement, Pearson correlation and receiver operating curves.
The median follow-up time was 54.3 months (IQR: 38.6-79 months). Two hundred and sixty-five patients achieved tumor response at 6 weeks. From the 6-week landmark, patients with tumor response were significantly associated with better OS (hazard ratio, HR = 0.566, P < 0.001, median OS: 30.3 versus 21.7 months) and PFS (HR = 0.426, P < 0.001, median PFS: 9.2 versus 7.3 months) than the patients without. After adjusting for potential confounders, the early tumor response was an independent prognostic factor associated with OS (HR = 0.539, 95% CI, 0.428 to 0.679, P < 0.001) and PFS (HR = 0.467, 95% CI, 0.378 to 0.576, P < 0.001), respectively. There was a good correlation between the early and best tumor response (Kappa: 0.82; Pearson: 0.83). The sensitivity, specificity, positive and negative predictive values of early tumor response in predicting best response were 100%, 79%, 88% and 100%.
Early tumor response is an independent prognostic factor in determining survival. The early and best tumor response correlated very well. The data could provide a basis for trial design that addresses alteration of first line chemotherapy intensity. Validation studies are awaited.
Clinical trial identification
Legal entity responsible for the study
Sun Yat-sen University Cancer Center.
National Natural Science Foundation of China.
All authors have declared no conflicts of interest.