Does pentoxifylline increase radiation response of Ehrlich mammary carcinoma in mice?

The presence of hypoxic cells in solid tumors is generally considered as a limiting factor for the complete control of tumors by radiation therapy. Pentoxifylline is a methylxanthine derivative that produces hemorrheologic effects which increase tissue oxygen levels. In this study we aimed to determine whether pentoxifylline would enhance the radiation response of Ehlrich mammary carcinoma in mice.

Ehrlich mammary carcinoma cells were subcutaneously transplanted into the nape of 27 male Balb/c mice. Twelve animals were injected with 50 mg/kg of pentoxifylline intraperitoneally (i.p.) and irradiated 30 min after the administration (study group). Fifteen mice were irradiated without receiving pentoxifylline (control group). All animals were exposed to a single dose of 40 Gy with Co60 gamma rays locally to the tumor site. The effect of pentoxifylline was assessed by the reduxtion rate in tumor volume (mm(3)) which was measured at least 3 times a week until mice were dead.

The reduxtion rate of tumor volume on day 4, relative to the initial volume, was 42% in the control group and 61.6% in the study group (p=0.24). The survival of mice in the two groups was not significantly different (p=0.08).

Although the reduction rate of tumor volume was higher in the study group, the difference was not statistically significant. Pentoxifylline can not be considered as a radiation enhancer in Ehrlich mammary carcinoma.