EFFECT OF RADIATION-THERAPY ON SMALL-CELL LUNG-CANCER IS REDUCED BY UBIQUINONE INTAKE

The effect of oral ubiquinone (Q(10)) intake on the in vivo response o f tumors to single dose radiotherapy was examined The human small-cell lung cancer (SCLC) line CPH 054A, which is sensitive to relatively lo w doses of X-radiation, was grown as subcutaneous transplants in the f lanks of nude nu/nu mice. When macroscopical growth was established, g roups of mice received either 10, 20 or 40 mg/kg Q(10) in 30 mt soy oi l intragastrically daily on 4 consecutive days. Controls received eith er 30 mt of pure soy oil or nothing. Three h after the last dose half of the tumors in each group received a single radiation dose of 5 Gy, using a 300 kV therapeutic unit. The macroscopic growth pre- and postt reatment was analyzed according to a transformed Gompertz algorithm us ing the software program GROWTH. Treatment with Q(10) or soy oil alone had no effect on tumor growth compared with untreated controls. Group s of tumors that received Q(10) and radiotherapy had a significantly l ower specific growth delay (SGD) than the radiotherapy-only groups. Th is effect was significant at 40 mg/kg and borderline at 20 mg/kg, wher eas at 10 mg/kg no radioprotection was seen. We conclude that systemic Q(10) reduces the response to single dose tumor irradiation inxenotra nsplanted human SCLC tumors.