Targeted Therapy-Induced Erythrocytosis in Thyroid Cancers: An Underrecognized Safety Signal from a Retrospective Study
Authors' conclusion
Erythrocytosis represents an underrecognized, early, recurrent, and indolent adverse event of antiangiogenic and targeted therapies, particularly RETi, in advanced thyroid cancer.
Study context
- Population
- Patients with any advanced thyroid cancer histology treated with antiangiogenic or targeted therapies (RETi, cabozantinib, dabrafenib + trametinib, lenvatinib, sorafenib, vandetanib), 2012–2023, two Italian referral centers173 screened
- Participants
- 135 patients
- Exposure
- Patients with vs without erythrocytosis on antiangiogenic or targeted therapies
- With erythrocytosisn = 24
- Outcome
- Erythrocytosis (2022 World Health Organization criteria), assessed by serial hemoglobin and hematocrit
- Follow-up
- Up to 36 months from treatment start
Methodological detailstwo Italian referral centers
- Two Italian referral centers
Main finding
As reported in the abstract
Erythrocytosis incidence
- Erythrocytosis occurred
- 24 patients (17.8%)
- Recurrent events
- 16/24 (66.6%)
- Total events
- 50
- Median time to onset
- 1.28 months (Q1-Q3: 0.76-5.14)
- Incidence with RETi (highest)
- 46.7%
- Incidence with vandetanib
- 20.7%
Observational data: associations, not effects.
Further findings
| Outcome | P value |
|---|---|
| DCRHigher DCR with erythrocytosis | P = 0.031 |
JAK2 testing
- No JAK2 V617F or exon 12 alterations among tested patients
- 14/24 tested
Management of erythrocytosis events
- Temporary treatment interruption
- 60.0% (30/50)
- Resumed at reduced dose
- 53.3% (16/30)
- Hematology-guided phlebotomy without drug discontinuation
- 4/9, 44.4%
Event-free survival (EFS), overall survival (OS), objective response rate (ORR)
- Erythrocytosis was not associated with EFS, OS, or ORR
Safety
Acute vascular events
Acute vascular events
- Comparable incidence
Original publication
Targeted Therapy-Induced Erythrocytosis in Thyroid Cancers: An Underrecognized Safety Signal from a Retrospective Study. Thyroid. Published 24 June 2026. doi:10.
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