CORRESPONDENCE

RESPONSE: Re: Is Less More? Lessons in Radiation Schedules in Breast Cancer

Carolyn I. Sartor, Joel E. Tepper

Affiliation of authors: C. I. Sartor, J. E. Tepper, Department of Radiation Oncology, University of North Carolina School of Medicine, Chapel Hill, NC.

Correspondence to: Carolyn Sartor, M.D., Department of Radiation Oncology, University of North Carolina School of Medicine, 101 Manning Dr., Rm. 1056, Campus Box 7512, Chapel Hill, NC 27599–7512 (e-mail: sartor{at}radonc.unc.edu).

We would like to take this opportunity to again congratulate Drs. Whelan et al. for their very well-designed and -conducted study. Our comments did not imply that the study’s results should not be widely applied to many breast cancer patients, as defined by the disease characteristics of those treated on the trial. Rather, as is true for interpretation of any clinical trial, one must use caution in extrapolating the results obtained from treatment of a defined patient population to a broader population in which the treatment was untested. In this respect, we believe that the authors’ suggested extension of shorter fractionation schedules to patients who were ineligible for participation in the trial is premature.

The results of any clinical trial predict the efficacy of the tested intervention in a future cohort of patients represented by those who were actually treated, not necessarily those who met the eligibility criteria. By their thorough (and highly commendable) reporting of the proportion of patients deemed eligible versus those actually enrolled, the authors illustrate that a substantial proportion of patients who met all eligibility criteria were not enrolled, raising the possibility that unmeasured, or unmeasurable, factors may contribute to selection of patients enrolled in the trial. We strongly agree that the degree of non-enrollment in this trial compares favorably with other studies. The problem of applying study results to patients with disease characteristics that would have made them eligible for a trial, but on which they were not in fact well-represented, is not unique to this study but is an issue frequently encountered in the medical literature. Thus, we urge caution in applying study results as the standard of care based solely on eligibility, when patients actually treated represent a more select group.

We believe that this important study will and should have a substantial impact on treatment patterns of patients with early-stage breast cancer. We hope that the use of shorter courses of radiotherapy will improve convenience of radiotherapy to the patient and reduce logistic barriers to receipt of appropriate care.



             
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