Guiding induction chemotherapy of locoregionally advanced nasopharyngeal carcinoma with ternary classification of predicted individual treatment effect

Abstract

Background and purpose

Induction chemotherapy (IC) before concurrent chemoradiotherapy does not universally improve long-term overall survival (OS) in locoregionally advanced nasopharyngeal carcinoma (LANPC). Conventional risk stratification often yields suboptimal IC decisions. Our study introduces a ternary classification of predicted individual treatment effect (PITE) to guide personalized IC decisions.

Materials and methods

A two-center retrospective analysis of 1,213 patients with LANPC was conducted to develop and validate prognostic models integrating magnetic resonance imaging and clinical data to estimate individual 5-year OS probabilities for IC and non-IC treatments. Differences in these probabilities defined PITE, facilitating patient stratification into three IC recommendation categories. Model effectiveness was validated using Kaplan–Meier estimators, decision curve-like analysis, and evaluations of variable importance and distribution.

Results

The models exhibited strong predictive performance in both treatments across training and cross-validation sets, enabling accurate PITE calculations and patient classification. Compared with non-IC treatment, IC markedly improved OS in the IC-preferred group (HR = 0.62, p = 0.02), had no effect in the IC-neutral group (HR = 1.00, p = 0.70), and worsened OS in the IC-opposed group (HR = 2.00, p = 0.03). The ternary PITE classification effectively identified 41.7 % of high-risk patients not benefiting from IC, and yielded a 2.68 % higher mean 5-year OS probability over risk-based decisions. Significantly increasing distributions of key prognostic indicators, such as metastatic lymph node number and plasma Epstein–Barr virus DNA level from IC-opposed to IC-preferred groups, further validated the clinical relevance of PITE classification.

Conclusion

The ternary PITE classification offers an accurate and clinically advantageous approach to guide personalized IC decision-making in patients with LANPC.