Table 4. Anatomic Stage/Prognostic Groupsa,b continued...
Stage III follicular thyroid cancer
Stage III is follicular carcinoma in patients older than 45 years, larger than 4 cm and limited to the thyroid or with minimal extrathyroid extension, or positive lymph nodes limited to the pretracheal, paratracheal, or prelaryngeal/Delphian nodes. Follicular carcinoma invading cervical tissue has a worse prognosis than tumors confined to the thyroid gland. The presence of vascular invasion is an additional poor prognostic factor. Metastases to lymph nodes do not worsen the prognosis in patients younger than 45 years.
Stage IV follicular thyroid cancer
Stage IV is follicular carcinoma in patients older than 45 years with extension beyond the thyroid capsule to the soft tissues of the neck, cervical lymph node metastases, or distant metastases. The lungs and bone are the most frequent sites of spread. Follicular carcinomas more commonly have blood vessel invasion and tend to metastasize hematogenously to the lungs and to the bone rather than through the lymphatic system. The prognosis for patients with distant metastases is poor.
Hürthle cell carcinoma
Hürthle cell carcinoma is a variant of follicular carcinoma with a similar prognosis and should be treated in the same way as equivalent stage non-Hürthle cell follicular carcinoma.
Medullary Thyroid Cancer
Several staging systems have been employed to correlate extent of disease with long-term survival in medullary thyroid cancer. The clinical staging system of the AJCC correlates survival to size of the primary tumor, presence or absence of lymph node metastases, and presence or absence of distance metastasis. Patients with the best prognosis are those who are diagnosed by provocative screening, prior to the appearance of palpable disease.
Stage 0 medullary thyroid cancer
Clinically occult disease detected by provocative biochemical screening.
Stage I medullary thyroid cancer
Tumor smaller than 2 cm.
Stage II medullary thyroid cancer
Tumor larger than 2 cm but 4 cm or smaller with no metastases or larger than 4 cm with minimal extrathyroid extension.
Stage III medullary thyroid cancer
Tumor of any size with metastases limited to the pretracheal, paratracheal, or prelaryngeal/Delphian lymph nodes.
Stage IV medullary thyroid cancer
Stage IV medullary thyroid cancer is divided into the following categories:
- Stage IVA (moderately advanced with or without lymph node metastases [for T4a] but without distant metastases).
- Stage IVB (very advanced with or without lymph node metastases but no distant metastases).
- Stage IVC (distant metastases).
Medullary carcinoma usually presents as a hard mass and is often accompanied by blood vessel invasion. Medullary thyroid cancer occurs in two forms, sporadic and familial. In the sporadic form, the tumor is usually unilateral. In the familial form, the tumor is almost always bilateral. In addition, the familial form may be associated with benign or malignant tumors of other endocrine organs, commonly referred to as the multiple endocrine neoplasia syndromes (MEN 2A or MEN 2B).