CAFFEINE CONSUMPTION IS ASSOCIATED WITH DECREASED SEVERE LATE TOXICITY AFTER RADIATION TO THE PELVIS

Purpose: Recent studies have suggested that pentoxifylline, a methylxa nthine, 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 radiati on injury. A retrospective study was undertaken to determine if there is an association between caffeine consumption and a lower incidence o f late radiation toxicity. Methods and Materials: From 1984 through 19 90, 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 ingestio n of caffeine-containing beverages, and average daily caffeine consump tion during the time of radiotherapy was estimated. The evaluable pati ents (42 cervical, 31 endometrial) were stratified by quantity of caff eine consumption for correlation with the incidence of radiation toxic ity. Results: Acute radiation toxicity was not associated with caffein e consumption for cervical or endometrial cancer, There was a nonstati stically 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 decreas ed incidence of severe late radiation injury in cervical cancer patien ts who consumed higher levels of caffeine at the time of their radioth erapy (p = 0.02). This relationship was not observable for late toxici ty in the endometrial cancer patients due to the low incidence of seve re late injury following radiation for that disease. Conclusions: This investigation is supportive of previous studies showing a radioprotec tive effect for pentoxifylline, and suggests that the mechanisms of ra dioprotection may be common to methylxanthines as a drug class.