Table 1.

Risk of death from thyroid cancer [5].

	Very low risk	Low risk	Intermediate risk	High risk
Age at diagnosis	<45 years	<45 years	Young patients (<45 years) Classic PTC >4 cm Vascular invasion Extrathyroidal extension Worrisome histology of any size‡	>45 years
Primary tumor size	<1 cm	1–4 cm	Older patients (>45 years) Classic PTC <4 cm Extrathyroidal extension Worrisome histology <1-2 cm confined to the thyroid‡	>4 cm classic PTC
Histology	Classic PTC, confined to the thyroid gland*	Classic PTC, confined to the thyroid gland*	Histology in conjunction with age as above	Worrisome histology >1-2 cm‡
Completeness of resection	Complete resection	Complete resection	Complete resection	Incomplete tumor resection
Lymph node involvement	None apparent	Present or absent†	Present or absent†	Present or absent†
Distant metastasis	None apparent	None apparent	None apparent	Present

Only those patients meeting all criteria within the respective column would be classified as very low risk or low risk. Older patients with either incomplete tumor resection or presence of distant metastasis are considered high risk irrespective of tumor size and specific histology. Patients with a combination of risk factors (age, histology, and tumor size) crossing over between columns are classified as intermediate-risk patients. PTC: papillary thyroid cancer.

*Confined to the thyroid gland with no evidence of vascular invasion or extrathyroidal extension.

^†Cervical lymph node metastases in older patients, but probably not in younger patients, may confer an increased risk of death from disease.

^‡Worrisome histologies include histologic subtypes of papillary thyroid cancer such as tall cell variant, columnar variant, insular variant, and poorly differentiated thyroid cancers.