Stage IVB Thyroid Gland Anaplastic Carcinoma AJCC v8

**Semantic type:** Neoplastic Process

**Definition:** Stage IVB includes: (T1-T3a, N1, M0); (T3b, Any N, M0); (T4, Any N, M0). T1: Tumor measuring 2 cm or less in greatest dimension limited to the thyroid. T2: Tumor measuring more than 2 cm but 4 cm or less in greatest dimension limited to the thyroid. T3a: Tumor measuring more than 4 cm in greatest dimension limited to the thyroid. T3b: Gross extrathyroidal extension invading only strap muscles (sternohyoid, sternothyroid, thyrohyoid, or omohyoid muscles) from a tumor of any size. T4: Tumor of any size with gross extrathyroidal extension. N1: Metastasis to regional nodes. M0: No distant metastasis. (from AJCC 8th Ed.)

**Synonyms:** - Stage IVB Thyroid Gland Undifferentiated (Anaplastic) Carcinoma AJCC v8 - Undifferentiated (Anaplastic) Stage IVB Thyroid Gland Cancer