Adjuvant therapy of breast cancer: compliance and data validity in a multicenter trial

Multicenter clinical trials are often large and complex, involving many institutions and investigators. The organizational structure is of vital importance in conducting and coordinating such trials. The present article describes the organization of a multicenter trial of adjuvant therapy of breast cancer. The trial is conducted since 1978 and involves all 15 hospitals in the Southern Swedish Health Care Region. The paper also describes methods of determining patient accrual rate, compliance with entrance criteria, diagnostic procedures, treatment, and follow-up. Comparison of data obtained from a population-based regional tumor registry revealed an accrual rate of more than 80%. Compliance with entrance criteria varied between the treatment groups from 85% to 97%. No patients were lost to follow-up. Compliance with diagnostic procedures and treatment was generally good. Reporting of recurrences was in accordance with data from patients' records in 98% of patients. One hundred thirteen patients died during the first 5 years of study. Twenty-one of these deaths were not reported to the secretariat. This strongly illustrates the necessity of matching to a population register before presenting data of such trials.