Impact of age on treatment effect in locally advanced head and neck cancer (HNC): Two individual patient data meta-analyses

5501 Background: The Meta-Analysis of Radiotherapy in Carcinomas of Head & Neck (MARCH; Bourhis J, ASTRO 2002) showed that altered fractionation radiotherapy (Alt-RT) could improve survival as compared to standard RT in patients with locally advanced HNC (pooled hazard ratio - HR -: 0.92, 95% confidence interval: 0.86–0.97). The Meta-Analysis of Chemotherapy in Head and Neck Cancer (MACH-NC; Bourhis J, ASCO 2004) demonstrated that concomitant chemotherapy (CT), added to RT, improved survival (HR: 0.82, 95% CI: 0.78–0.86). This study considers age as a potential modifier of the treatment effect. Methods: 15 randomized trials with 6,515 patients were included in MARCH (median follow up: 6.0 years), and 50 with 9,471 patients in concomitant part of MACH-NC (median follow up: 5.6 years). The interaction between age and treatment effect, using HR of death, was tested with heterogeneity test. Effect of prognostic factors on the interaction was analysed using Cox model. Results: The effect of Alt-RT in MARCH and...