Doctors could use a cut-off level of 2ng/mL for stimulated thyroglobulin to determine which patients with papillary thyroid cancer are more likely to have post-op recurrence, Australian researchers say.

The Sydney-based team examined data for 502 patients who had undergone total thyroidectomy followed by radioactive iodine ablation for papillary tumours of 1cm or more in diameter between 2000 and 2016.

Those who had a stimulated thyroglobulin level of 2ng/mL or less — measured soon after surgery and before ablation — had less than a 5% risk of cancer recurrence at 18-month follow-up.

This compared with a 30% risk of recurrence for those with a level higher than 2ng/mL, said the researchers from the University of Sydney’s endocrinology unit and Royal North Shore Hospital.