The most commonly used classification for thyroid cancer is TNM (UICC).
The TNM system describes the extent of the disease at the time it is diagnosed.
- "T" describes the extent of the local tumor in and around the thyroid gland.
- "N" (node) expresses whether there is spreading to lymph nodes.
- "M" describes the absence or presence of distant metastasis.
The TNM classification differentiates between the clinical classification (TNM) and the pathological classification (pTNM). For thyroid cancer, pTNM is used. This system is based on observations made before treatment, supplemented and modified according to observations made during the surgical treatment, and the subsequent histo-pathological examination.
In order to carry out the pTNM classification, sufficient tissue must be available for the histology examination.
- pTx - primary tumor cannot be assessed
- pT0 - no evidence of primary tumor
- pT1 - tumor ≤ 2 cm, intra thyroideal
- pT2 - tumor > 2 cm, but ≤ 4 cm, intra thyroideal
- pT3 - tumor > 4 cm intra thyroideal, or with minimal extra thyroideal growth (to m sternothyroideus or perithyroideal tissue)
- pT4a - tumor regardless of size, outside thyroid capsule, with subcutaneous invasion, in the larynx, trachea, esophagus, recurrence
- pT4b - tumor regardless of size, with invasion in prevertebral fascia, carotis, mediastinal vessel tumor
- pT4a - intra thyroideal tumor
- pT4b - extra thyroideal tumor
- pNx - tumor cannot be assessed
- pN0 - no regional lymph node metastasis
- pN1a - metastasis in level VI
- pN1b - metastasis to unilateral, bilateral, or contralateral cervical or superior mediastinal lymph nodes
- pMx - cannot be assessed
- pM0 - no distant metastsis
- pM1 - metastasis (provide localization)
Assessment of risk
- Risk assessment before treatment is critical for the choice of the primary treatment.
- Risk assessment after treatment is over is critical for the choice of follow-up plan.