CBX4 and NOX4 Expression Are Associated With Chemoradiotherapy Response and Overall Survival in Locally Advanced Cervical Squamous Cell Carcinoma.

BACKGROUND

Tissue biomarkers may improve risk stratification in locally advanced cervical cancer before definitive concurrent chemoradiotherapy (CCRT). We evaluated pretreatment expression of chromobox 4 (CBX4), NADPH oxidase 4 (NOX4), specificity protein 1 (SP1), and copper transporter 1 (CTR1) in relation to CCRT response and overall survival.

METHODS

In this retrospective 1:1 matched case-control study, pretreatment biopsies from 40 patients with locally advanced cervical squamous cell carcinoma (20 CCRT-resistant, 20 CCRT-sensitive) were quantified by AI-assisted digital pathology using H-scores. A parsimonious CBX4 + NOX4 logistic model was evaluated by apparent ROC, leave-one-out cross-validation (LOOCV), repeated stratified 5-fold cross-validation, and bootstrap optimism correction. Overall survival analyses were exploratory.

RESULTS

CBX4 and NOX4 expression was lower in CCRT-resistant tumors (median H-score: CBX4, 40.47 vs. 79.62; NOX4, 7.00 vs. 53.93; both p < 0.001), whereas SP1 and CTR1 did not differ. Apparent AUCs were 0.840 for CBX4 and 0.843 for NOX4. The two-marker model had an apparent AUC of 0.903, LOOCV AUC 0.845, repeated 5-fold CV AUC 0.854 ± 0.022, and bootstrap-corrected AUC 0.883. High CBX4 and NOX4 expression was associated with better 5-year overall survival; in joint Cox models, hazard ratios per 1-SD increase were 0.31 (95% CI 0.13-0.74) for CBX4 and 0.48 (0.26-0.90) for NOX4. No histochemically detectable copper deposits were observed.

CONCLUSIONS

Lower pretreatment CBX4 and NOX4 expression was associated with a CCRT-resistant phenotype and poorer overall survival in this small, response-enriched cohort. Internal resampling suggested discrimination, but same-dataset marker selection may introduce residual optimism and does not establish generalizability. Independent validation in a consecutively recruited cohort is required before clinical application. No mechanisms involving DNA repair, ROS, or chemoradiotherapy sensitivity were established.