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Thank you for your valuable feedback on our article. There is still ongoing controversy regarding the definition of endpoints in clinical research. In our study, the primary endpoint was disease-free survival (DFS), defined as the time from the date of diagnosis to the confirmation of locoregional recurrence (LRR) or distant metastasis (DM). The secondary endpoints included locoregional recurrence-free survival (LRFS), distant metastasis-free survival (DMFS), overall survival (OS), and safety. OS was defined as the time from the date of diagnosis to the date of death from any cause, or the last known date when the patient was alive. LRFS referred to the time from diagnosis to the date of LRR, while DMFS referred to the time from diagnosis to the date of DM [1]. The correspondence from Dr. Erkan Topkan [2] indicated that death must also be considered an event in the results concerning LRFS, DMFS, and DFS.
Several prospective studies on nasopharyngeal carcinoma have used LRFS and DMFS as study outcomes, defining them as time to LRR or DM [3-5], rather than using death as the endpoint for LRFS and DMFS, as suggested by Dr. Erkan Topkan. Additionally, the definition of DFS in current literature remains controversial. Some definitions of DFS, similar to those by Delgado and Guddati [6], describe it as the “time from randomization to disease recurrence.” However, other definitions also include “the time until the date of death or first metastasis, progression, or recurrence” [5,7], which aligns with Dr. Erkan Topkan’s definition. Therefore, an accurate definition of survival endpoints can facilitate a more precise determination of patient survival outcomes and provide an important basis for the results of clinical studies.
We have redefined DFS to include patients who experienced death as one of its endpoints, yielding similar results before (p< 0.001) and after propensity score matching (p=0.005). We would like to express our gratitude once again to Dr. Erkan Topkan for providing valuable feedback on our research.
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