Cancer in first-degree relatives and risk of glioma in adults.

Relatively few studies have examined glioma risk in relation to history of cancer in first-degree relatives. We sought to describe such risks in a large hospital-based case-control study. Histologically confirmed incident adult glioma cases (n = 489) were identified at three regional referral hospitals between June 1994 and August 1998. Controls (n = 799) admitted to the same hospitals for nonmalignant conditions were frequency-matched on age, sex, race/ethnicity, hospital, and proximity of residence to hospital. Participants received a personal interview, including questions regarding cancer in family members. Odds ratios (ORs) were calculated to estimate the risk of glioma associated with a history of cancer in a first-degree relative using conditional logistic regression and compared with standardized incidence ratios among relatives of cases versus relatives of controls. Among participants reporting a family history of a brain cancer or a brain tumor, risk of glioma was 1.6 [95% confidence interval (CI), 0.5-5.3; n = 5] and 3.0 (95% CI, 0.9-10.8; n = 7), respectively, in comparison with those without such family histories. Participants who had a family history of stomach (OR, 2.2; 95% CI, 1.0-4.6), colon (OR, 1.4; 95% CI, 0.9-2.2), or prostate cancer (OR, 2.1; 95% CI, 1.1-3.8) or Hodgkin disease (OR, 2.4; 95% CI, 0.9-6.3) had an increased glioma risk. OR estimates were similar to the ratios of standardized incidence ratios for cancer in relatives of cases versus controls. Shared environmental or genetic factors in families may influence glioma risk. Our findings suggest that individuals with a family history of specific cancers other than glioma may have an increased glioma risk.