Clinical predictors of radiation-induced lymphopenia in patients receiving chemoradiation for glioblastoma: clinical usefulness of intensity-modulated radiotherapy in the immuno-oncology era

Table 3 Univariate and multivariate logistic regression analyses for acute severe lymphopenia

	Univariate HR (95% CI)	P	Multivariate HR (95% CI)	P
Patient-related factor
Age (per 1 year)	1.02 (1.00–1.03)	0.098
Sex (Male vs. Female)	0.30 (0.18–0.47)	<.001	0.33 (0.19–0.55)	<.001
KPS
(80 vs. ≤70)	0.90 (0.53–1.56)	0.716
(≥90 vs. ≤70)	0.54 (0.30–0.97)	0.038
Baseline TLC (< 1000/μL vs. ≥1000/μL)	1.83 (1.09–3.07)	0.021	1.69 (0.94–3.03)	0.082
Tumor-related factor
Extent of resection
(Subtotal/Partial vs. Total)	2.85 (1.75–4.64)	<.001	2.40 (1.40–4.11)	0.001
(Biopsy vs. Total)	1.57 (0.62–3.94)	0.338	2.43 (0.84–6.98)	0.100
IDH1 mutation
(Yes vs. No)	0.64 (0.21–2.01)	0.447	0.75 (0.22–2.57)	0.649
(Unknown vs. No)	2.68 (1.56–4.64)	<.001	1.83 (0.93–3.62)	0.079
MGMT (Methylated vs. Unmethylated)	0.69 (0.43–1.11)	0.122
Subventriclular zone (Involved vs. Uninvolved)	1.27 (0.80–2.00)	0.308
Treatment-related factor
The cumulative dose of temozolomide (per 100 mg/m²)	0.98 (0.97–1.00)	0.087	0.99 (0.97–1.02)	0.530
PTV1 volume (per 10 cm³)	1.02 (1.00–1.03)	0.012	1.02 (1.00–1.03)	0.042
PTV2 volume (per 10 cm³)	1.02 (1.00–1.05)	0.083
Radiotherapy modality (IMRT vs. 3D-CRT)	0.32 (0.19–0.51)	<.001	0.48 (0.27–0.87)	0.015
Total dose (per 1 Gy)	0.95 (0.89–1.01)	0.072
No. of fractionation (per 1)	0.99 (0.90–1.08)	0.749

Abbreviations: 3D-CRT three-dimensional conformal radiotherapy, CI confidence interval, HR hazard ratio, IMRT intensity-modulated radiotherapy, KPS Karnofsky performance status, PTV planning target volume, TLC total lymphocyte count

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