Significance of boost dose for T4 nasopharyngeal carcinoma with residual primary lesion after intensity-modulated radiotherapy

Previous studies showed poorer survival in T4 disease with residual lesion. To evaluate the efficacy and toxicity of a boost dose for T4 nasopharyngeal carcinoma (NPC), patients with a residual primary lesion after intensity-modulated radiotherapy (IMRT). 398 T4 NPC patients with residual primary lesions after radical IMRT were retrospectively reviewed. An IMRT boost dose of 4–6.75 Gy was delivered to the residual lesions in 2–3 fractions. Propensity score matching (PSM) was applied to balance potential confounders between groups (ratio, 1:2). The presence of Epstein–Barr virus (EBV) DNA in plasma after IMRT was used for risk stratification. Patients who received boost radiation had significantly improved overall survival (OS) and local recurrence-free survival (LRFS) compared with those who did not (all P