Table 2: Recommendations for the screening and management of thyroid disorders during anticancer therapy.
| Drug | Screening | Management |
|---|---|---|
| Immune checkpoint inhibitors12,13 | TSH and FT4 before initiation, should be repeated before each cycle | Primary hypothyroidism: start standard LT4 therapy: initial full dose (1.6 mcg/kg) in young and healthy; reduced dose in elderly or patients with cardiovascular disease |
| Thyroiditis: usually self-limited, beta blockers may be given for a short duration | ||
| Graves’ disease: standard therapy | ||
| Central hypothyroidism due to hypophysitis: start LT4 at 1 mcg/kg, adjust dose by monitoring FT4 every 6–8 weeks, rule out or treat associated hypocortisolism before initiation | ||
| Tyrosine kinase inhibitors37 | Euthyroid patients TSH at initiation and then monthly (or on first day of new cycle) for first 6 months. TSH every 2–3 months thereafter or on symptoms Prior hypothyroidism TSH monthly for first 3 months, followed by 3-monthly throughout the therapy period |
Primary hypothyroidism: treat if TSH >10 mIU/L or TSH 5–10 mIU/L on two assays, with clinical symptoms, positive anti-TPO antibodies or ultrasound signs of autoimmune thyroiditis Replacement dose between 1.0–1.6 mcg/kg |
| Thyroiditis: usually self-limited, beta blockers may be given for a short duration | ||
| Graves’ disease: standard therapy | ||
| Prior hypothyroidism: increased levothyroxine requirement as adjudged by TSH value | ||
| I-131 MIBG therapy79 | TSH and FT4 at baseline and at every 3–6 months | Primary hypothyroidism: LT4 therapy if TSH level >10 mIU/L. Some authorities recommend treatment even with TSH 5–10 mIU/L, because of theoretical risk of malignancy due to radiation |
| Bexarotene93–5 | TSH and FT4 at initiation of therapy | Central hypothyroidism: start LT4 at 25–50 μg along with bexarotene. FT4 levels every 1–2 weeks for first 4 weeks; dose adjusted to maintain it at upper third of normal. Monthly FT4 once levels stable. Treatment discontinued on stopping bexarotene. Prior hypothyroidism: increased LT4 requirement, and can increase 2–3 times; should be adjusted according to FT4 levels |
FT4 = free thyroxine; I-131 MIBG = iodine-131 metaiodobenzylguanidine; LT4 = levothyroxine; TPO = thyroid peroxidase; TSH = thyroid-stimulating hormone.