HiLo there.

Results of the phase 3 HiLo trial were presented last week at the NCRI cancer conference in the UK and are leading to international guideline changes. Over 400 patients with “low risk” differentiated thyroid cancer post-total thyroidectomy were randomized to receive radioactive iodine (RAI) doses of the standard 3.7 GBq (100 mCi) versus the experimental 1.1 GBq (30 mCi). The experimental dose buys the (often young) patient less radiation exposure, less isolation time, and less dry mouth. Side note: salivary glands are pretty sensitive to even small doses RAI. In a 2x2 design, enrollees were also randomized to synthetic TSH injection 2 days prior to RAI versus simply coming off T4 replacement therapy 4-6 weeks prior—both used as ways to drive up thyroid intake of the RAI. After 7 years of follow-up there were 10 recurrences in the standard arm and 11 in the experimental one, with no differences between 2 days of synthetic TSH versus several days of T4 depletion (aka several days of feeling lousy). TBL: The RAI dose threshold for case logs needs to take it down a notch. | Wadsley, NCRI 2018