Correlation of smoking history and other patient characteristics with major complications of pelvic radiation therapy for cervical cancer

Purpose: The purpose of this study was to identify patient-related factors that influence the risk of serious late complications of pelvic radiation therapy. Patients and Methods: The records of 3,489 patients treated with radiation therapy for International Federation of Gynecology and Obstetrics stage I or II carcinoma of the cervix were reviewed for information about patient characteristics, treatment details, and outcomes. Any complication occurring or persisting more than 3 months after treatment that required hospitalization, transfusion, or an operation or caused severe symptoms or the patient's death was considered a major late complication. Complication rates were calculated actuarially. The median duration of follow-up was 85 months, and 99% of patients were followed for at least 3 years or until they died. Results: Heavy smoking was the strongest independent predictor of overall complications (multivariate hazard ratio, 2.30; 95% confidence interval [Cl], 1.84 to 2.87). The most striking influence of smoking was on the incidence of small bowel complications (hazard ratio for smokers of one or more packs per day, 3.25; 95% Cl, 2.21 to 4.78). Hispanics had a significantly lower rate of small bowel complications than whites, and blacks had higher rates of bladder and rectal complications than whites. Thin women had an increased risk of gastrointestinal complications, and obese women were more likely to have serious bladder complications. Conclusion: Complications of pelvic radiation therapy are strongly correlated with smoking, race, and other patient characteristics. These factors should be considered before the results of clinical studies are generalized to different cultural and racial groups.