The Comprehensive Repair-Inflammation Index (CRII) Predicts Tooth Extraction After Chemoradiotherapy: A Continuous...

Background: Tooth extraction (TE) after chemoradiotherapy is common in locally advanced nasopharyngeal carcinoma (LA-NPC), yet its determinants remain unclear. We evaluated the association between the Comprehensive Repair-Inflammation Index (CRII), reflecting systemic inflammation and host repair capacity, and TE risk after concurrent chemoradiotherapy (CCRT). Methods: We conducted a retrospective analysis of 354 patients with LA-NPC treated with definitive CCRT. The primary endpoint was post-treatment TE (none vs. ≥1). CRII was calculated from pre-treatment laboratory parameters and analyzed continuously, with a breakpoint identified via segmented regression. Logistic regression and restricted cubic splines were used. Multivariable models adjusted for clinical variables and mandibular dosimetric parameters (mean dose, V50, V60). Results: TE occurred in 70.1% of patients. CRII was significantly higher in those with TE (147.5 vs. 122.0; p < 0.001). CRII was strongly associated with TE (per 10-unit increase: OR 1.49, 95% CI 1.34-1.66; p < 0.001). A nonlinear relationship was observed, with a breakpoint at 145.7, above which TE rates increased markedly (90.5% vs. 58.8%; p < 0.001). CRII remained independently predictive after adjustment (adjusted OR 1.46; ≥145.7: OR 5.1; both p < 0.001). Mandibular dose parameters were not significantly associated with tooth extraction in this analysis. Conclusions: CRII independently predicts post-CCRT TE with a nonlinear risk pattern, highlighting the potential contribution of systemic host-related factors alongside conventional dosimetric parameters.