Outcomes of postmastectomy radiotherapy

In 1995 the American Society of Clinical Oncology adopted a statement on the choice of outcomes in assessing cancer treatments.¹ That statement made a clear distinction between patient outcomes (survival and quality of life) and cancer outcomes (tumour regression), the former being much more important. This view is also expressed in current books on cancer therapy.² A recently published guideline, though devoted to techniques of measuring tumour response, stated that this outcome is of value as an endpoint in early clinical trials, but in phase III trials and clinical application “it should not be the sole, or major, endpoint.”³ Yet the clinical practice guidelines published in CMAJ concerning the use of postmastectomy radiotherapy⁴ appear to be founded entirely on evidence related to tumour responsiveness. Although local irradiation is effective in destroying local tumour tissue, none of the relevant clinical trials have shown that this leads to an improvement in overall survival. Normally, acceptance of a therapeutic modality requires demonstration of its efficacy, yet leading oncologists appear to take the opposite stance in regard to radiotherapy. Thus it is assumed, despite a lack of supporting evidence, that the majority of patients “require” irradiation but that subgroups who do not benefit will ultimately become recognizable.^5,6

The authors of the guidelines are to be commended for including a “questions and answers” guide for women and their physicians (Appendix 1 of the article).⁴ But one important question has been omitted: “How will radiation help me?” One must wonder how many of the patients anxiously waiting for radiation therapy are among those for whom therapy has been recommended despite a lack of evidence of benefit. If such patients were given balanced information and allowed to choose whether to undergo therapy, how many would decide against it?

Norman Kalant Sir Mortimer B. Davis Jewish General Hospital Montréal, Que.