Table 2

Family history of brain tumors and risk of glioma: risks estimated by standardized incidence ratios (SIRs) and odds ratios (ORs), overall and by age at interview

Family history ofCases N (%)Controls N (%)SIR gliomaaSIR glioma/SIR controlsOR (95% CI)b,c
(n = 468)(n = 768)
 Brain cancer5 (1.1)6 (0.8)0.7 (0.2–1.7)1.11.6 (0.5–5.3)
 Benign brain tumors7 (1.5)4 (0.5)dd3.0 (0.9–10.8)
 Brain tumor (unknown if benign or malignant)11 (2.4)27 (3.5)dd0.7 (0.3–1.4)
Age 18–49 yrs at interviewn = 227n = 396
 Brain cancer3 (1.3)4 (1.0)1.4 (0.3–4.0)1.41.4 (0.5–12.3)
 Benign brain tumor5 (2.2)2 (0.5)dd3.7 (0.7–20.6)
 Brain tumor (unknown if benign or malignant)5 (2.2)5 (1.3)dd0.9 (0.3–3.1)
Age ≥50 yrs at interviewn = 241n = 372
 Brain cancer2 (0.8)2 (0.5)0.4 (0.1–1.6)1.01.4 (0.2–10.4)
 Benign brain tumor2 (0.8)2 (0.5)dd0.6 (0.1–8.9)
 Brain tumor (unknown if benign or malignant)6 (2.5)22 (5.9)dd0.3 (0.1–0.9)
  • a Glioma only, no controls.

  • b The reference group for each odds ratio estimate was comprised of study participants without a family history of the particular cancer of interest and can be obtained by subtracting from the total of 468 cases and 768 controls. CI, confidence interval.

  • c Odds ratio estimates were adjusted for age at interview (continuous), race (white, nonwhite), sex, study hospital, proximity of residence to hospital (<15 miles, ≥15 miles).

  • d Standardized incidence ratios were not calculated because the expected numbers of cases of benign brain tumors or those of unknown behavior (benign or malignant) were not available from the Connecticut Tumor Registry.