Genetic susceptibility markedly increases the risk of developing radiation-associated meningioma—a rare brain tumour—according to a study published today in the May issue of THE LANCET ONCOLOGY. "Our study showed that in families which included a member who developed radiation-associated meningioma, and in which additional siblings were irradiated, a high rate of meningioma and other radiation-related tumours was found," say study authors Drs Flint-Richter and Sadetzki. "This contrasts with the rarity of familial meningioma in the general population and supports the notion that genetic susceptibility is involved in the development of these tumours".
Ionising radiation is the only known, clearly established, risk factor for the development of meningioma. However, less than 1% of individuals who are irradiated will develop the tumour suggesting that other factors are also important. In the 1950s, in Israel and other countries, radiation was administered to immigrants, mainly from north Africa and the middle east, to treat a fungal infection of the scalp (tinea capitis). Several of these patients developed radiation-related cancers in the ensuing years and the cohort provides a unique natural experiment to study risk factors for the development of these cancers.
Flint-Richter and Sadetzki therefore assessed the number of meningiomas and other radiation-related cancers seen in a subset of this cohort including 525 families divided into four groups according to whether the index participant in each family had meningioma and whether or not they were irradiated. An additional first-degree relative with meningioma was found in 17 families (11%) of the group with an index participant with radiation-associated meningioma (RAM group) whereas only between one and two such families (1%) were found in each of the other three groups. Furthermore, 22 siblings (10%) in the RAM group had members with cancer in irradiated sites compared with only 9 siblings (5%) among the irradiated controls.
In an accompanying comment, Prof Eric Hall (Columbia University Medical Center, New York, USA) discusses the implications of the Israeli data, if confirmed, for radiation protection standards: current standards are based on the assumption that the human population is uniform in its sensitivity to radiation but The Lancet Oncology data conflict with this paradigm. Furthermore, Hall points out confirming such data will be difficult, with confirmatory studies likely to be in smaller populations than in the tinea capitis cohort.
Indeed, the authors Flint-Richter and Sadetzki conclude: "Further studies should focus on the identification of specific genes that are involved in this inherited familial sensitivity to ionising radiation. DNA repair and cell cycle control genes, such as the ataxia-telangiectasia gene, could be plausible candidates for investigation".
Journal
The Lancet Oncology