RADIATION-THERAPY QUALITY-CONTROL IN A CLINICAL-TRIAL OF ADJUVANT POSTOPERATIVE TREATMENT FOR RECTAL-CANCER

Purpose: Deviations from protocol can detract from the reliability of results obtained in prospective clinical trials. In an effort to decre ase the number of deviations in a prospective trial of adjuvant treatm ent for rectal cancer, we undertook pretreatment review of the irradia ted fields. Methods and Materials: Before initiation of radiation ther apy, patients' radiation therapy fields were simulated by their radiat ion oncologists and films were submitted for review. The treating phys icians were then informed whether their fields were in compliance with the protocol or whether any modifications were needed. Results: Among the 625 patients participating in this study who received radiation t herapy as a component of protocol treatment, 419 (67%) had no radiatio n therapy deviations, 127 (20%) had minor deviations, and 51 (8%) had major deviations; 28 (4%) could not be evaluated or did not receive pr otocol treatment because of circumstances beyond the treating radiatio n oncologist's control. The pretreatment quality control review identi fied major deviations in the radiation portals for 57 cases; these fin dings were communicated to the radiation oncologists prior to initiati on of treatment, and, on final review, 40 had no deviation or only min or deviation. Conclusion: In the absence of pretreatment quality contr ol review, 40 additional patients would have had major deviations from their radiation therapy protocol. On the basis of these findings, it is estimated that pretreatment quality control reduced the rate of maj or deviation from 15% to 8%, Pretreatment review of radiation therapy parameters is an effective method of reducing the frequency of major d eviations in prospective clinical trials.