Letter to the Editor From Zandee and Links: “Metastatic Differentiated Thyroid Cancer Survival Is Unaffected by Mode of Preparation for 131I Administration”

Response to Letter to the Editor from Zandee and Links: “Metastatic Differentiated Thyroid Cancer Survival Is Unaffected by Mode of Preparation for 131I Administration”

“…Insofar as our study did reach this conclusion, they express concern that we may have overstated that the results achieved by the 2 approaches were equivalent due to underpowering of the study. While our conclusions are supported by prior analyses as cited in our paper [ 3 , 4 ], Zandee and Links [ 2 ] indicate that perhaps due to the multifarious nature of factors influencing thyroid cancer survival (in our subjects and presumably in general) that the failure to observe a statistically significant difference between the outcomes derived from the 2 approaches does not signify that they can be considered equivalent. While this inference is arguable, in our view it renders any conclusion inutile or ambiguous.…”

“…In our view, there is little doubt that use of recombinant human thyrotropin (rhTSH) has proved of significant benefit to patients with low- or intermediate-risk differentiated thyroid cancer (DTC). And in their communication regarding our study [ 1 ], Zandee and Links [ 2 ] present compelling arguments with which we fully agree on the importance and merits of also establishing that preparation by rhTSH for radioiodine (RAI) therapy of higher risk or metastatic DTC would be equally efficacious to preparation by thyroid hormone withdrawal. Insofar as our study did reach this conclusion, they express concern that we may have overstated that the results achieved by the 2 approaches were equivalent due to underpowering of the study.…”

“…Our cautionary conclusion was that the choice of preparation for RAI would not “decisively affect outcome” because outcomes in the 2 groups of patients did not significantly differ statistically. We acknowledged multiple potential shortcomings of our study including the number of patients, duration of follow-up, selection bias, and retrospective design, and, as do Zandee and Links [ 2 ], look to the need for a perhaps international, carefully controlled larger study to more definitively resolve this question. Until such confirmatory data are available, we are comfortable continuing to offer the option of rhTSH preparation for RAI therapy to our patients with metastatic disease, with or without dosimetry, taking into account multiple factors known to influence either adverse or beneficial aspects of RAI therapy on an individual, personalized basis.…”