Ionizing radiation and the risk of brain and central nervous system tumors: a systematic review

Abstract

Although exposure to moderate-to-high doses of ionizing radiation is the only established environmental risk factor for brain and CNS tumors, it is not clear whether this relationship differs across tumor subtypes, by sex or age at exposure, or at the low-to-moderate range of exposure. This systematic review summarizes the epidemiologic evidence on the association between ionizing radiation exposure and risk of brain/CNS tumors. Articles included in this review estimated radiation exposure doses to the brain and reported excess relative risk (ERR) estimates for brain/CNS tumors. Eight cohorts were eligible for inclusion in the analysis. Average age at exposure ranged from 8 months to 26 years. Mean dose to the brain ranged from 0.07 to 10 Gy. Elevated risks for brain/CNS tumors were consistently observed in relation to ionizing radiation exposure, but the strength of this association varied across cohorts. Generally, ionizing radiation was more strongly associated with risk for meningioma compared with glioma. The positive association between ionizing radiation exposure and risk for glioma was stronger for younger vs older ages at exposure. We did not observe an effect modification on the risk for meningioma by sex, age at exposure, time since exposure, or attained age. The etiologic role of ionizing radiation in the development of brain/CNS tumors needs to be clarified further through additional studies that quantify the association between ionizing radiation and risk for brain/CNS tumors at low-to-moderate doses, examine risks across tumor subtypes, and account for potential effect modifiers.

Brain tumor risk according to germ-line variation in the MLLT10 locus

“…Female gender, African ancestry and exposure to ionizing irradiation are well-established risk factors. [1][2][3] Several familial syndromes are associated with an increased incidence of meningioma and other nervous system tumors 4 , and genetic susceptibility is also documented in these tumors. 5 In a recent genome-wide association (GWA) study (859 meningioma cases and 704 controls in the discovery phase), 5 a region localizing to 10p12.31 was identified as harboring risk variants for meningioma.…”

Occupational exposure to metals and risk of meningioma: a multinational case-control study

“…Ionizing radiation is the only environmental factor that has been shown unequivocally to be a risk factor for meningioma development [2][3][4]. Data is globally concordant with the biologic hypothesis assuming that female sex hormones may increase the risk of meningioma [5].…”

Pooled analysis of Swedish case-control studies during 1997–2003 and 2007–2009 on meningioma risk associated with the use of mobile and cordless phones

“…The corresponding results for cordless phones were a median of 8.0 years (mean 8.2 and range 2-21). Mean cumulative mobile phone use for the cases was 881 h (median 176 and range 1-33,215) and for controls 784 h (median 192 and range [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19]756). Regarding cordless phone use, the mean cumulative time for cases was 1,309 h (median 487 and range 3-58,400) and for controls 861 h (median 365 and range [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18]980).…”

“…The only well-established risk factor is ionizing radiation with a long latency period (time from first exposure until diagnosis) encompassing decades (4,5). Sex hormones may be of importance due to the female predominance, yet the role is unclear and has been suggested not to fully explain the higher incidence in women (6).…”