Table 2.

Multivariable Cox regression models for risk of meningioma by demographic and treatment-related risk factors (model 1) and by age at diagnosis/cranial radiotherapy dose (model 2), and cranial radiotherapy volume/dose (model 3) combinations^a

	N Total	N Cases	Model 1		Model 2		Model 3
			HR	95% CI	HR	95% CI	HR	95% CI
Sex
Male	3269	47	REF		REF		REF
Female	2574	50	1.36	0.91–2.04	1.36	0.91–2.04	1.37	0.92–2.06
Age at diagnosis
0–4 y	2641	46	2.38	1.39–4.07			2.35	1.40–3.96
5–9 y	1583	26	1.09	0.62–1.91			1.10	0.63–1.94
10–17 y	1619	25	REF				REF
CrRT exposure
No CrRT	4525	3	0.04	0.01–0.15
1–19 Gy	324	10	REF
20–39 Gy	445	48	1.66	0.83–3.33
40+ Gy	493	35	2.81	1.30–6.08
Exposed cranial volume
Partial CrRT			REF
Full CrRT			1.66	0.86–3.22	1.40	0.73–2.66
Carboplatin
No	5396	88	REF		REF		REF
Yes	409	9	3.55	1.62–7.78	4.26	1.95–9.31	4.31	1.97–9.45
CrRT exposure (age/dose)
No CrRT	4525	3			0.01	0.00–0.05
0–4 y / ≤25 Gy	313	31			REF
0–4 y / >25 Gy	153	15			1.84	0.95–3.56
5+ y / ≤25 Gy	382	23			0.47	0.27–0.81
5+ y / >25 Gy	414	24			0.61	0.33–1.13
CrRT exposure (volume/dose)
No CrRT	4525	3					0.01	0.00–0.05
Partial CrRTb / ≤25 Gy	13	0					REF
Partial CrRTb / >25 Gy	300	14
Full CrRT / ≤25 Gy	682	54					1.03	0.56–1.89
Full CrRT / >25 Gy	267	25					1.45	0.75–2.83

Abbreviations: CI = confidence interval; CrRT = cranial radiotherapy; Gy = Gray; HR = Hazard Ratio; N = number; REF = reference category.

^aModels include only 96 meningioma cases due to missing values.

^bDose groups were collapsed.