Stopping Metastases at Their Source

In this issue of the Journal, two papers address the role of radiation therapy in patients with breast cancer treated with adjuvant chemotherapy. These prospective, randomized trials from Denmark1 and Canada2 present 15-year results. Although this long follow-up is necessary for a proper evaluation, the question the studies ask and the results they present must be interpreted in terms of the current practice of breast-cancer management. Stating the purpose of the studies explicitly is useful, but to appreciate the implications of the results fully we need to consider the hypotheses of tumor pathogenesis that underlie the therapeutic maneuvers being tested. . . .