Radiation dose escalation for locally advanced nasopharyngeal carcinoma patients with local and/or regional residual lesions after standard chemoradiotherapy: a non-randomized, observational study

Table 2 Clinical characteristics of study participants

Prognostic factor	3-year LRRFS	χ²	P^a	3-year DMFS	χ²	P^a	3-year FFS	χ²	P^a	3-year OS	χ²	P^a
Gender		2.977	0.084		2.245	0.134		5.094	0.024		1.091	0.296
Male	82.9			88.5			72.9			89.5
Female	89.3			94.2			83.7			96.3
Age		1.414	0.234		0.209	0.648		0.544	0.461		2.276	0.131
≤ 65	85.6			89.7			76.4			91.7
> 65	72.3			94.7			68.2			84.4
Plasma EBV-DNA (copies/mL)		0.384	0.536		0.001	0.976		0.124	0.725		0.776	0.378
≤ 500	83.0			90.6			75.3			90.0
> 500	87.7			88.5			76.4			93.6
T category		0.013	0.911		0.707	0.401		0.587	0.444		0.069	0.793
T 1–2	82.0			93.1			78.7			91.0
T 3–4	85.2			89.4			75.3			91.4
N category		1.449	0.229		0.235	0.628		1.994	0.158		0.226	0.634
N 0–1	87.9			90.2			79.5			92.3
N 2–3	83.0			89.9			73.8			90.7
Stage		0.238	0.626		2.024	0.155		1.922	0.166		1.184	0.277
III	85.7			91.4			78.2			93.3
IVA	83.3			88.7			73.2			88.9
Time to boost after radiotherapy (days)		1.077	0.584		1.749	0.417		0.902	0.637		0.432	0.806
1–14	92.0			81.6			73.8			90.0
15–28	88.8			90.5			79.7			95.4
> 28	81.2			92.4			75.0			90.2
Sites of residual		3.533	0.171		8.580	0.014		4.181	0.124		12.631	0.002
Primary focus	79.4			98.8			78.2			94.5
Lymph nodes	90.2			87.4			78.4			92.4
Primary focus + lymph nodes	76.2			77.7			57.6			75.9

Statistically significant value is shown in bold
DMFS distant metastasis-free survival, EBV-DNA Epstein-Barr virus-deoxyribonucleic acid, FFS failure-free survival, LRRF locoregional relapse-free survival, OS overall survival
^aLog-rank test

ISSN: 1748-717X