Variations in diagnostic and therapeutic procedures in a multicentre, randomized clinical trial (EORTC 10853) investigating breast-conserving treatment for DCIS

Aims To evaluate the diagnostic and therapeutic procedures which were followed in a European Organization for Research and Treatment of Cancer (EORTC) randomized clinical trial investigating the role of radiotherapy in breast-conserving treatment (BCT) for ductal carcinoma in situ (DCIS) of the breast. Methods The medical files of 824 of the 1010 randomized patients (82%) were reviewed during site visits to 30 participating institutes. Results Large variations occurred, particularly in the surgical procedures and histopathological work-up which were performed. Important risk factors like tumour size and margin status were poorly quantified in the medical files. Conclusions These findings emphasize the need for establishing uniform guidelines for diagnostic and therapeutic procedures for DCIS, and for clearly defined risk factors for recurrence after BCT for DCIS. Because of its randomized nature, the main question of the trial, i.e. the effect of radiotherapy on the risk of local recurrence, will not be influenced by variation. The risk of local recurrence in itself, and hence the success of BCT for DCIS, may however be influenced by the quality of the initial procedures that were conducted.