Brachytherapy

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(2014) 1

Letter to the Editor

Response to Dr Sabater We greatly appreciate the interest that Dr Sabater has shown in our work (1) and agree that clustering secondary to repeat measurements is a valid point that should be addressed in our work. To this point, we have undertaken two secondary analyses to eliminate this clustering effect entirely and confirm the overall conclusions. The first included dosimetry from only the first fraction from each woman, and confirmed the association with bowel D2cc and D0.1cc at a p-value #0.001 in both univariate and multivariate analysis. This analysis did not confirm the association with bladder dose (all p O 0.2), however, urinary catheters were often used on the first fraction, creating a potential confounding factor. The second approach was to take only the last fraction from each woman, where catheters were less commonly used. This continued to confirm the association with bowel dose ( p ! 0.001 for univariate and !0.01 for

multivariate for D0.1cc and D2cc). The association with bladder dose was of borderline significance (D2cc, p 5 0.143 and D0.1cc, p 5 0.075); when controlling for catheter use in a multivariate model, the associations were stronger at p ! 0.02 for both D0.1 and D2cc. We are grateful for the point raised by Dr Sabater, which we feel strengthens the work as a whole, while confirming the conclusions made. John Boyle, MD Junzo Chino, MD Department of Radiation Oncology Duke University Medical Center Durham, NC Reference [1] Boyle JM, Craciunescu O, Steffey B, et al. Body mass index, dose to organs at risk during vaginal brachytherapy, and the role of threedimensional CT-based treatment planning. Brachytherapy 2014;. [E-pub ahead of print].

1538-4721/$ - see front matter Ó 2014 American Brachytherapy Society. Published by Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.brachy.2014.05.008

Response to Dr Sabater.

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