PTC transformation into anaplastic thyroid carcinoma component (DTC→ATC dedifferentiation...

Deterministic view of the source YAML entity. Clinical authority remains with the cited source IDs and reviewer sign-off state.

ID	`RF-THYROID-PAPILLARY-TRANSFORMATION-PROGRESSION`
Type	Red flag
Status	reviewed 2026-04-27 \| pending_clinical_signoff
Diseases	`DIS-THYROID-PAPILLARY`
Sources	`SRC-ATA-THYROID-2015` `SRC-NCCN-THYROID-2025`

Red Flag Origin

Definition	PTC transformation into anaplastic thyroid carcinoma component (DTC→ATC dedifferentiation, ~5-15% of long-standing PTC), progression to RAI-refractory metastatic disease (no iodine uptake on therapy scan, RECIST progression on therapeutic ¹³¹I activities), rapid thyroglobulin doubling time (<1 yr — adverse prognostic), new bulky lung / bone / brain metastases, or rapid progression on lenvatinib — triggers re-staging, re-biopsy of progressing lesion, salvage second- line TKI (cabozantinib post-lenvatinib) or selective TKI if molecular rebiopsy reveals actionable target.
Clinical direction	hold
Category	transformation-progression

Trigger Logic

{
  "any_of": [
    {
      "finding": "dtc_to_atc_dedifferentiation",
      "value": true
    },
    {
      "finding": "rai_refractory",
      "value": true
    },
    {
      "comparator": "<",
      "finding": "thyroglobulin_doubling_time_months",
      "threshold": 12
    },
    {
      "finding": "new_metastatic_disease",
      "value": true
    },
    {
      "finding": "rapid_progression_on_tki",
      "value": true
    }
  ],
  "type": "composite_clinical"
}

Notes

Thyroglobulin doubling time <12 months is a validated adverse prognostic marker (Miyauchi et al, JCEM 2011) — predicts shorter OS in DTC. RAI refractoriness defined per ATA criteria (Schlumberger consensus): no uptake at diagnosis, lesion-level uptake but no response, or progression after RAI ≥600 mCi cumulative. Lenvatinib is 1L for RAI-refractory progressive PTC (SELECT trial); cabozantinib COSMIC-311 is FDA-approved 2L post-lenvatinib (PFS 11 vs 1.9 mo placebo). DTC→ATC dedifferentiation: re-biopsy any new rapidly enlarging mass (especially neck) — disease tempo changes dramatically. Brain metastases rare in PTC; if present, consider stereotactic RT + CNS-penetrant TKI. Selpercatinib for RET-fusion / pralsetinib for RET-fusion pediatric / adolescent.

Used By

No reverse references found in the YAML corpus.