Table 2.

Standardized Incidence Ratios by Proband Characteristics (Age, Tumor Histology), Relative's Age at Diagnosis, and Relationship for Glioma in First-Degree Relatives, 1994–2006 (MDACC), 1991–2004 (UCSF), and 1958–1997 (Sweden)

	MDACC				UCSF				Sweden
	No.	No. Observed	SIR	95% CI	No.	No. Observed	SIR	95% CI	No.	No. Observed	SIR	95% CI
Proband's age, years
≤19	302	0			0	0			5,689	15	2.35	1.31, 3.87
20–50	4,788	21	2.13	1.32, 3.26	2,181	10	1.99	0.95, 3.67	16,510	55	2.42	1.83, 3.16
>50	3,497	24	2.21	1.41, 3.28	3,944	25	1.87	1.21, 2.76	15,803	36	2.19	1.53, 3.03
Proband's histology
High grade	7,029	31	1.73	1.18, 2.46	4,926	30	1.94	1.31, 2.77	24,156	114	1.76	1.45, 2.11
Low grade	1,558	14	4.29	2.34, 7.19	1,199	5	1.71	0.55, 4.00	14,006	62	1.54	1.18, 1.97
Relative's age, years
<45	4,283	21	6.01	3.72, 9.18	2,373	12	5.68	2.93, 9.93	29,154	85	1.80	1.43, 2.22
≥45	4,304	24	1.36	0.87, 2.02	3,744	23	1.42	0.90, 2.13	8,848	91	1.57	1.27, 1.93
Relationship
First-degree relatives	8,587	45	2.12	1.55, 2.84	6,125	35	1.90	1.32, 2.65	38,002	176	1.67	1.43, 1.94
Siblings	2,505	2	1.12	0.13, 4.04	2,323	15	2.20	1.23, 3.64	6,352	22	3.31	2.08, 5.02

Abbreviations: CI, confidence interval; MDACC, MD Anderson Cancer Center; SIR, standardized incidence ratio; UCSF, University of California, San Francisco.