Low-risk differentiated thyroid cancer (ATA risk)

Low-risk differentiated thyroid cancer, as defined by the ATA risk system, is intrathyroidal papillary or follicular cancer with no vascular invasion, no aggressive histology and at most five microscopic nodal metastases. Such cancers are almost always cured by surgery alone: the ESTIMABL2 and IoN trials showed that radioiodine ablation adds nothing, and lobectomy rather than total thyroidectomy is acceptable for tumours of 4 cm or less. Readers meet the category in the radioiodine therapy and active surveillance entries, on the radioactive iodine drug page and under TSH suppression, which is tailored to this risk level. It matters because it is the group most exposed to overtreatment, which is why the overdiagnosis bottleneck links here.