SATOSHI KUROSE

Abstract Background Cancer-related weight loss is associated with poor prognosis, reduced treatment tolerance, and impaired quality of life. Recent studies have highlighted the importance of oral health in maintaining nutritional status among older adults. Oral frailty, a reversible stage of oral function decline, has been linked to reduced food intake and systemic frailty. However, the relationship between oral frailty and weight loss in patients with lung cancer undergoing chemotherapy remains unclear. This study aimed to identify factors associated with weight loss, with a particular focus on oral frailty, in this population. Methods This single-center retrospective study included 67 patients with lung cancer who received outpatient chemotherapy at Kansai Medical University Hospital between October and December 2024. Oral frailty was evaluated using the 5-item Oral Frailty Checklist (OF-5) by non-dental clinicians on the day of chemotherapy. Weight loss was defined as an unintentional loss of > 5% within 6 months. Logistic regression models were constructed to examine associations between oral frailty, dysgeusia, and weight loss, adjusting stepwise for performance status, C-reactive protein, sex, and cancer stage. Model robustness was confirmed using bootstrap resampling (1,000 replications). Results Nineteen patients (28.4%) experienced significant weight loss. In multivariate analyses, oral frailty (odds ratio [OR]: 28.79, 95% confidence interval [CI]: 1.81–36.05, p  = 0.006) and dysgeusia (OR: 39.84, 95% CI: 1.76–40.62, p  = 0.001) were independently associated with weight loss after adjustment for confounders. These associations remained robust in bootstrap analyses. No multicollinearity was detected among variables. Conclusions Oral frailty and dysgeusia were significantly associated with weight loss in patients with lung cancer receiving chemotherapy. Screening for oral frailty using the simple OF-5 checklist, even when performed by non-dental clinicians, may facilitate early identification of patients at risk for nutritional decline. Multidisciplinary supportive care, including oral and taste function management, should be integrated into oncology practice to help mitigate cancer-related weight loss.