Caffeine consumption is associated with decreased severe late toxicity after radiation to the pelvis

Recent studies have suggested that pentoxifylline, a methylxanthine, can prevent or ameliorate late radiation injury in animals and humans. Caffeine is a commonly consumed methylxanthine that provides a model for evaluating the impact of this category of drugs on radiation injury. A retrospective study was undertaken to determine if there is an association between caffeine consumption and a lower incidence of late radiation toxicity.

From 1984 through 1990, 82 patients with cervical cancer and 53 patients with endometrial cancer were treated with primary or adjuvant radiation therapy at the University of Washington. Patients were interviewed regarding ingestion of caffeine-containing beverages, and average daily caffeine consumption during the time of radiotherapy was estimated. The evaluable patients (42 cervical, 31 endometrial) were stratified by quantity of caffeine consumption for correlation with the incidence of radiation toxicity.

Acute radiation toxicity was not associated with caffeine consumption for cervical or endometrial cancer. There was a nonstatistically significant trend toward a decrease in overall late radiation toxicity with increased caffeine intake for cervical cancer patients. Subgroup analysis revealed this trend to be attributable to a decreased incidence of severe late radiation injury in cervical cancer patients who consumed higher levels of caffeine at the time of their radiotherapy (p = 0.02). This relationship was not observable for late toxicity in the endometrial cancer patients due to the low incidence of severe late injury following radiation for that disease.

This investigation is supportive of previous studies showing a radioprotective effect for pentoxifylline, and suggests that the mechanisms of radioprotection may be common to methylxanthines as a drug class.