Figure 3. Failure-Free Survival According to Subgroup.

^aHazard ratios (HRs) and the associated 95% CIs were calculated using an unadjusted Cox proportional hazards model, which was also used to carry out the interaction test, incorporating the interaction term (eg, age × treatment), a covariate of interest (eg, sex), and the trial group. An HR of less than 1 indicated a decreased risk of failure-free survival after intensity-modulated radiation therapy alone compared with that after concurrent chemoradiotherapy.

^bThe index of Karnofsky performance scales is a primarily subjective score of physical ability used to assess the ability of a patient to carry on normal activities in life from normal health (100) to disabled (50) and death (0).

^cAccording to the 7th edition TNM Staging System. ; T1: Nasopharynx, oropharynx or nasal cavity without parapharyngeal extension; T2: Parapharyngeal extension; T3: Bony structures of skull base and/or paranasal sinuses; N0: No regional lymph node metastasis; N1: Unilateral cervical, unilateral or bilateral retropharyngeal lymph nodes, above the supraclavicular fossa; ≤6 cm.

^dStage II includes T2N0 and the T1-2N1 subset; stage III includes T3N0 subset.