Effect of radiation therapy on small-cell lung cancer is reduced by ubiquinone intake.

The effect of oral ubiquinone (Q10) intake on the in vivo response of tumors to single dose radiotherapy was examined. The human small-cell lung cancer (SCLC) line CPH 054A, which is sensitive to relatively low doses of X-radiation, was grown as subcutaneous transplants in the flanks of nude nu/nu mice. When macroscopical growth was established, groups of mice received either 10, 20 or 40 mg/kg Q10 in 30 mL soy oil intragastrically daily on 4 consecutive days. Controls received either 30 mL 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 posttreatment was analyzed according to a transformed Gompertz algorithm using the software program GROWTH. Treatment with Q10 or soy oil alone had no effect on tumor growth compared with untreated controls. Groups of tumors that received Q10 and radiotherapy had a significantly lower specific growth delay (SGD) than the radiotherapy-only groups. This effect was significant at 40 mg/kg and borderline at 20 mg/kg, whereas at 10 mg/kg no radioprotection was seen. We conclude that systemic Q10 reduces the response to single dose tumor irradiation inxenotransplanted human SCLC tumors.