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

Methods

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 IDH1 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.
Results
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%, p=0.01). Among 122 patients, 24 (19.7%) of them carried IDH1 mutation. Smoking patients have a significantly higher proportion of IDH1 mutation compared with non-smokers (31.4% vs. 14.9%, p<0.001). No significant association was found between intensity and duration of smoking with IDH1 mutations and glioma grading. No significant association was found between smoking and MGMT promoter methylation.
Conclusions
In glioma patients, smoking is associated with IDH1 mutations and grading but not with MGMT promoter methylation.