Cytogenetic and Molecular gene array analyses of radiation‐induced meningiomas

We studied 20 radiation‐induced meningiomas RIMs seen since 1993 for cytogenetic alterations and clinical outcome. Most were WHO grade I tumors. Abnormalities of chromosome 1p and/or LOH 1p36 was identified in 5 of 11 informative cases, with monosomy 22 in 4. Most could be managed surgically, either with a single extensive resection or with re‐resection. Several have shown no growth and have required no neurosurgical intervention. Stereotactic radiosurgery or radiation + chemotherapy have been used selectively (6). Affymetrix gene array study in 2 examples were compared to a large number of other tumors (n=52) and showed that RIMs clustered closely with radiation‐induced sarcoma and Ewing's sarcoma, but not with radiation‐induced glioblastomas. RIMs generally have a favorable prognosis, although therapy needs to be individually tailored. Gene microarray illustrates a more distinctive “signature” for RIMs than does cytogenetic analysis.