Dynamic Variation and Prognostic Value of Weight Loss During Radiotherapy in Nasopharyngeal Carcinoma: A Large-Scale Cohort Study

Abstract Background: We aim to investigate the dynamic variation and prognostic value of weight loss among patients with nasopharyngeal carcinoma (NPC). Methods: A total of 1149 newly diagnosed NPC patients who received radical radiotherapy (RT) were retrospectively analyzed. Patients’ weights were measured at initiation of RT and every week during RT. Recursive partitioning analyses (RPAs) were utilized to determine cut-off value for rate of weight loss (RWL). Disease-free survival (DFS) was our primary endpoint. Secondary endpoints included locoregional relapse-free survival (LRRFS), distant metastasis-free survival (DMFS), and overall survival (OS).Results: RWLs were 0%, 0%, -1.54%, -2.86%, -4.11%, -5.98%, -6.56% at 1st, 2nd, 3rd, 4th, 5th, 6th, and 7th week of RT, respectively. RWL optimal threshold with respect to DFS was -5.3% based on RPAs. Thus, a consistent threshold of -5% (> -5% versus ≤ -5%) was selected to classify NPC patients into low RWL and high RWL groups for survival analysis. Compared to high RWL (≤-5%), patients with low RWL (> -5%) had significantly better ten-year DFS (78.6% versus 61.2%; P< 0.001), OS (86.6% versus 70.1%; P< 0.001), and DMFS (88.5% versus 80.2%; P = 0.007). However, no difference was observed between LRRFS groups (91.7% versus 94.3%; P= 0.173). In multivariate analysis, high RWL was an independent risk factor for DFS (HR, 1.56; 95% CI, 1.19-2.03; P= 0.001), OS (HR, 1.54; 95% CI, 1.11-2.15; P= 0.011) and DMFS (HR, 1.47; 95% CI, 1.03-2.10; P= 0.033) in patients with NPC. Additionally, chemotherapy and old age were attributed to the development of high RWL.Conclusions: Weight loss during RT was significantly associated with decreased survival among NPC patients. Clinicians should continuously inform patients on the health impact of minimizing weight loss under 5%.