Author Affiliations: Department of Surgical Disciplines, All India Institute of Medical Sciences, Delhi (firstname.lastname@example.org).
To the Editor: The Z0011 trial suggests that there is no difference in DFS or OS between patients treated by ALND or SLND alone.1 However, we have concerns about a number of aspects of the study. First, the authors used dynamic balance randomization to distribute important covariates equally in the 2 groups, stratifying patients according to age, ER status, and tumor size. However, in Table 1, data on these variables were missing for 17 to 81 patients. Without information on these factors, how could the randomization be accomplished and balance ascertained?
Vuthaluru S, Srivastava A. Axillary vs Sentinel Lymph Node Dissection for Invasive Breast Cancer. JAMA. 2011;305(22):2288–2291. doi:10.1001/jama.2011.755