Table 7.

Issues specific for childhood cancer survivors developing subsequent differentiated thyroid cancer

Issue	Example	Possible consequence
Previous radiation dose from prior diagnostics and treatment	High cumulative radiation dose	Avoidance, when possible, of CT scan or I-131 in the evaluation and treatment of DTC
Previous exposure to toxic agents for the childhood cancer	Bleomycin increases the risk of pulmonary dysfunction Alkylating agents and abdominal irradiation increase the risk of gonadal dysfunction Total body irradiation or 131I-MIBG treatment increases the risk of bone marrow toxicity and tertiary malignancies Chest irradiation increases the risk for breast cancer	May increase the risk for adverse effects of I-131 in the treatment for DTC
Possibility of the presence of a genetic predisposition syndrome	Possible underlying genetic mutation may be present, both causing the childhood malignancy and the thyroid malignancy; the fact that an individual has already had cancer during childhood and subsequently develops thyroid cancer may indicate a germline genetic susceptibility to develop cancer	May influence the decision to use adjuvant treatment with I-131 with regard to the risk of developing a third malignancy
Risk of cardiotoxicity and prescribing levothyroxine therapy	Anthracycline chemotherapy agents or chest irradiation may increase the risk of cardiotoxicity	Consider keeping TSH levels in the lower normal but not in suppressed range
Psychological aspects	Fear of unfavorable prognosis similar to the previous cancer	The psychological impact of DTC diagnosis as a second primary malignancy may be higher than the diagnosis of sporadic DTC

DTC, differentiated thyroid carcinoma; MIBG, meta-iodobenzylguanidine; TSH, thyroid-stimulating hormone.

Adapted, with permission, from van Santen et al. (136).