Radiation-induced lymphopenia correlates with survival in nasopharyngeal carcinoma: impact of treatment modality and the baseline lymphocyte count

Table 2 Univariate Cox regression analysis demonstrates associations between baseline variables and lymphocyte nadirs during RT

Characteristic	ALC < 0.5 × 10⁹ Cells /L			ALC < 0.2 × 10⁹ Cells /L
Characteristic	HR	95% CI	P value	HR	95% CI	P value
Sex
Female	1			1
Male	0.997	0.772–1.288	0.636	1.424	0.672–3.018	0.357
Age at diagnosis (years)	0.992	0.979–1.004	0.183	0.964	0.932–0.997	*0.033*
ALC baseline	0.591	0.469–0.744	*< 0.001*	0.443	0.235–0.834	*0.012*
Body mass index	0.961	0.925–0.998	*0.041*	0.935	0.836–1.045	0.236
Smoking status (pack*year)	1	0.999–1.000	0.193	1	0.999–1.001	0.636
Tumor histologic type (WHO)
Undifferentiated (III)	1			1
Differentiated (I and II)	0.666	0.516–1.525	0.887	1.152	0.535–2.481	0.717
Stage
II	1			1
III	1.419	0.941–2.139	0.102	1.942	0.455–8.284	0.37
Iva	1.53	0.968–2.416	0.097	4.098	0.931–18.037	0.062
Induction or concurrent chemotherapy (N)
None	1			1
Induction only	1.201	0.757–1.9007	0.971	0.794	0.230–2.745	0.716
Concurrent only	1.142	0.726–1.796	0.566	1.221	0.409–3.644	0.721
Both	1.545	1.043–2.290	*0.03*	1.011	0.375–2.725	0.983
RT modality
2D-CRT	1			1
IMRT	1.594	1.233–2.061	*< 0.001*	2.148	1.099–4.200	*0.025*

Abbreviations: CI confidence interval, HR hazard ratio, 2D-CRT 2-dimensional conventional radiotherapy, IMRT intensity modulated radiation therapy, GTV gross tumor volume, WHO World Health Organization, ALC absolute lymphocyte count

ISSN: 1748-717X