Total dietary antioxidant index and survival in patients with glioblastoma multiforme

Objectives The role of antioxidants in survival of cancer patients is controversial. No data on the relationships between antioxidant intake and survival of glioma patients are available. Our objective was to examine such association in a large series of cases. Methods The study population includes 814 glioblastoma multiforme cases that were newly diagnosed, histologically confirmed, aged 20 or older, and residing in the San Francisco Bay Area at diagnosis. Cases were identified via the regional cancer registry's rapid case ascertainment system during 1991-1994 (series I), 1997-2000 (series II), and 2001-2004 (series III). Daily dietary antioxidant intake at diagnosis was assessed via food-frequency questionnaire and was expressed as total antioxidant index, calculated based on Trolox equivalent per gram of food. In addition, the study collected information on supplements/vitamin intake. Results Overall, our results indicated no consistent, significant association of survival with dietary antioxidant intake or its combination with vitamin supplements. However, in series III, we observed a significant association between higher antioxidant index and better survival: HR = 0.58 (95% CI: 0.46, 0.74) for each unit of antioxidant index on a log-scale. Conclusions Although it is possible that this is a chance finding, the association between dietary antioxidants and survival in the most recently recruited patients warrants further investigations.