Adjuvant irradiation for early breast cancer. An on-going controversy

Adjuvant irradiation has been used in the treatment of breast cancer for over 80 years, but its use has always been, and remains, controversial. It is extremely valuable in the treatment of Stage III and IV breast cancer because of its ability to reduce the local recurrence rate in these late stages down to acceptably low levels; however, to have a significant benefit in Stages I and II, in which the local recurrence rate is only 10% to 20% with mastectomy alone, it should be able to improve survival as well as prevent local recurrence. All of the early trials indicated that adjuvant irradiation neither increased nor decreased survival; however, these trials were flawed by poorly executed randomization processes and/or by the use of radiotherapy that would be considered inadequate by today's standards. The two recent trials, Oslo and Stockholm, which were more stringently randomized and which employed more modern radiotherapy techniques, showed an improved disease-free survival with adjuvant irradiation. Overall, survival, however, was unaffected, save for the small subset of patients with medial tumors and histologically positive axillary nodes. For these patients there was a trend toward survival enhancement by internal mammary node irradiation. All of the trials testing irradiation and surgery against surgery alone have very little relevance in today's adjuvant chemotherapy era; thus, the entire question of survival enhancement by irradiation must be reassessed within the context of adjuvant chemotherapy. Will the combination of adjuvant chemotherapy and irradiation yield a better survival than either adjuvant modality alone? The results of the few prospective trials that have addressed this question are still preliminary, and longer follow-up is necessary before any conclusions can be reached. Also, future studies must be undertaken to address two issues that may be very important when combining chemotherapy and radiotherapy: the sequencing of these two modalities, and the optimum radiotherapy technique for minimizing hematologic suppression.