Response to the commentary letter entitled 'Diagnostic radiography and thyroid cancer - causation or simply an association?' to our article entitled 'Diagnostic radiography exposure increases the risk for thyroid microcarcinoma: a population-based case-control study' that was published in the Europe

Our study population included incident thyroid cancer patients who were diagnosed with papillary (84.8%), follicular (12.1%), medullary (2.6%), anaplastic (0.2%), or other thyroid cancers (0.2%). Well-differentiated thyroid cancers included both papillary and follicular thyroid cancer cases; they accounted for 96.9% of all cases. We had limited statistical power to analyze the data for medullary and anaplastic thyroid cancer subtypes. We agree with the comment by Dr Wiltshire and Dr Balasubramanian that our study results can only speak for well-differentiated thyroid cancers. Future studies with sufficient statistical power are needed to investigate whether diagnostic radiography is associated with other thyroid cancers (namely, medullary and anaplastic cancers).