Management of childhood cancer survivors at risk for thyroid function abnormalities: A Delphi study

Background: Thyroid function abnormalities can occur after treatment for childhood cancer. Evidence for the management of thyroid dysfunction among asymptomatic childhood cancer survivors (CCS) is lacking. We used a Delphi consensus methodology to expand guidelines for screening asymptomatic CCS at risk for thyroid dysfunction and explore recommendations for the clinical management of abnormal results. Procedure: A Delphi panel of 40 expert physicians representing oncology, endocrinology, and primary care participated in three rounds of anonymous, iterative questionnaires formatted as clinical scenarios. Consensus is defined as ≥ 90% of panelists agree with recommendation and disagreement as < 70% agree. Results: Panelists reached consensus that CCS treated with radiation including neck, total body, whole brain, brain including the hypothalamic-pituitary axis (HPA), and therapeutic meta-iodobenzylguanidine (MIBG) should have annual, lifelong screening using serum thyroid-stimulating hormone (TSH) and free T4 starting within one year off-treatment (98%). Panelists disagreed on continuing to screen CCS for thyroid dysfunction after immunotherapy associated with acute thyroid injury (31%-50%). There was also disagreement on indications for brain (17%-43%) or thyroid (50%-65%) imaging, laboratory tests to assess the HPA (29%-75%), and TSH threshold to initiate treatment of subclinical hypothyroidism. Lack of evidence was the most frequent rationale panelists offered for not recommending additional testing or medications. Panelists’ recommendations did not vary by geography, specialty, or survivorship clinical experience. Conclusions: Consensus was reached on most recommendations for screening and management of cancer treatment-related thyroid dysfunction. Screening after completion of thyroid-toxic immunotherapy, indications for imaging, and treatment of subclinical hypothyroidism are areas of disagreement for further investigation.