Associations among smoking, IDH mutations ,MGMT promoter methylation, and grading in glioma a cross-sectional study

<b>Methods</b><br>Patients were recruited from Dr. Sardjito General Hospital (a referral hospital in Yogyakarta and Central Java region) and its network hospitals. Genomic DNA was extracted from formalin-fixed paraffin-embedded samples or fresh glioma tissues. Identification of <i>IDH1</i> mutation was performed using Polymerase Chain Reaction-Restriction Fragment Length Polymorphism (PCR-RFLP) or DNA sequencing. Methylation-specific real-time PCR was performed to identify MGMT promoter methylation status. Smoking status was obtained by history taken from the patient or family members.<b>Results</b>In total, 122 patients were included in this study. As many as 35 patients (28.7%) had a smoking history. Most smokers (57.1%) smoke less than ten cigarettes per day. However, most of them (68.8%) have been smoking for more than 20 years. Smoking patients have a significantly higher proportion of high-grade glioma than non-smokers (80% vs. 55.2%, <i>p</i>=0.01). Among 122 patients, 24 (19.7%) of them carried <i>IDH1</i> mutation. Smoking patients have a significantly higher proportion of <i>IDH1</i> mutation compared with non-smokers (31.4% vs. 14.9%, <i>p</i>&lt;0.001). No significant association was found between intensity and duration of smoking with <i>IDH1</i> mutations and glioma grading. No significant association was found between smoking and MGMT promoter methylation.<b>Conclusions</b>In glioma patients, smoking is associated with <i>IDH1</i> mutations and grading but not with MGMT promoter methylation.