Table 2. Summary of multivariate analysis of different prognostic factors in 1800 patients with NPC.

Endpoint	Factor	HR	95% CI	P
Progression	Age > vs. ≤45 yrs	1.25	0.99–1.58	0.06
or death	Sex female vs. male	1.00	0.76–1.31	0.99
	Chemotherapy yes vs. no	0.94	0.63–1.41	0.76
	AJCC T-category T3–4 vs. T1–2	1.71	1.30–2.24	<0.01
	AJCC N-category N2–3 vs. N0–1	2.19	1.72–2.78	<0.01
	PLN metastasis yes vs. no	1.92	0.71–5.21	0.20
Death	Age > vs. ≤45 yrs	1.48	1.03–2.12	0.04
	Sex female vs. male	0.85	0.55–1.31	0.46
	Chemotherapy yes vs. no	0.70	0.37–1.31	0.26
	AJCC T-category T3–4 vs. T1–2	2.77	1.74–4.42	<0.01
	AJCC N-category N2–3 vs. N0–1	3.58	2.48–5.17	<0.01
	PLN metastasis yes vs. no	2.48	0.78–7.91	0.13
Distant failure	Age > vs. ≤45 yrs	1.09	0.81–1.48	0.57
	Sex female vs. male	0.75	0.51–1.09	0.13
	Chemotherapy yes vs. no	1.14	0.64–2.04	0.65
	AJCC T-category T3–4 vs. T1–2	1.78	1.25–2.52	<0.01
	AJCC N-category N2–3 vs. N0–1	2.74	2.01–3.73	<0.01
	PLN metastasis yes vs. no	3.15	1.16–8.60	0.03
Regional	Age >vs. ≤45 yrs	0.87	0.52–1.46	0.60
failure	Sex female vs. male	1.70	1.01–2.87	0.05
	Chemotherapy yes vs. no	0.80	0.36–1.80	0.59
	AJCC T-category T3–4 vs. T1–2	1.16	0.67–2.01	0.59
	AJCC N-category N2–3 vs. N0–1	1.92	1.15–3.19	0.01
	PLN metastasis yes vs. no	2.72	0.37–20.00	0.33

Abbreviations: HR = hazard ratio; CI = confidence interval; PLN = parotid lymph nodes. The 11 patients whose involved parotid lymph nodes were not irradiated were excluded from this analysis.