Findings from NSABP protocol no. B‐04‐comparison of radical mastectomy with alternative treatments for primary breast cancer. I. Radiation compliance and its relation to treatment outcome

Between 1971 and 1974, 1,665 women with primary operable breast cancer were entered into a prospective randomized clinical trial (NSABP Protocol No. B‐04) in order to compare the worth of radical mastectomy with alternative treatments. Six‐hundred forty‐six of the women, 352 clinically nodenegative and 294 node‐positive, were randomized so that they were to have been treated with total mastectomy and postoperative radiation. Due to a meticulous comprehensive program of radiation monitoring involving close cooperation between the NSABP Headquarters, the NSABP Radiation Monitoring Committee, the Radiological Physics Center at M. D. Anderson Cancer Center and participating institutions, it has been possible to determine protocol compliance of the radiation administered and to correlate any variation of radiation employed with treatment outcome. At the onset of the study and prior to any evaluation of treatment results, the Radiation Monitoring Committee defined minor variations from the protocol which were acceptable and those variations which were more major and unacceptable. While it was found that 53% of the 543 evaluable patients had been treated by radiation having some degree of variation from the protocol, it was ascertained that 77% of the 2.172 irradiated fields of those patients (82% in clinically node‐negative and 71% in clinically node‐positive patients) received radiation per protocol. Only 6.7% of all sites were the recipients of a major (unacceptabel) variation in radiation. Analysis of data demonstrated that there was a remarkable similarity in the incidence and rate of treatment failure (TF) or mortality between patients having some radiation variation, regardless of its degree or extent and those who were treated with no protocol variation. Results were similar when comparisons were made taking into consideration either the degree (minor or major low) or the extent (one or more than one field) of the radiation variation. A substantial number of clinically positive axillary node patients received only the radiation to the axillary field intended for those with clinically negative nodes, i.e., they failed to receive the specified radiation boost. Despite that deviation, there was no difference in TF or survival from those receiving the prescribed treatment. Moreover, findings were not different when the axilla was the only site of radiation deviation or there were deviations to other fields as well. Of singular importance was an inability to a