**3. Role of staging and risk stratification in differentiated thyroid carcinoma (DTC) patients**

Disease staging is recommended for all patients with DTC not only as a requirement of the cancer registries but also as a factor determining the following treatment, risk assessment, and prediction of disease recurrence or persistence as well as disease mortality. Moreover, in the last years, risk stratification for thyroid cancer patients has changed from a single-point assessment at the time of the diagnosis and initial treatment to a more dynamic and changing overtime risk evaluation [16, 52].

TO No evidence of primary tumor


Any tumor with minimal extrathyroidal spread (e.g., extension into sternothyroid muscle or perithyroid soft tissues)


**Table 2.** AJCC 7th edition of TNM classification system for differentiated thyroid carcinoma (adapted from the AJCC cancer staging manual. Seventh edition (adapted from edge et al. [53]).

T1a Tumor < 1 cm in greatest dimension. limited to the thyroid. without extrathyroidal extension

The initial staging of each patient is performed post-operatively mainly on the basis of the histology report, according to the seventh edition of the TNM classification of the American Joint Committee of Cancer (AJCC), presented on **Table 2** [53]. Additionally to the TNM score, the age of the patient is also important, as young age (≤ 45 years) is considered a favorable factor upstaging the young patients with any T, any N and M0 in stage I and, respectively, young patients with distant metastases in stage II. However, some studies have questioned this "young age benefit" in the presence of lymph node metastases [54].

**Ongoing (dynamic) risk stratification** reflects the changes of recurrence risk during the follow-up period, which depends on the natural history of the disease and the patient's response

Thyroid Cancer: Diagnosis, Treatment and Follow-Up http://dx.doi.org/10.5772/intechopen.77163 59

Initial treatment of DTC includes surgery and post-operative administration of radioiodine (if indicated) and the initiation of levothyroxin therapy. In rare cases (locally aggressive thyroid

Thyroid surgery is an important element of the initial therapy for thyroid carcinoma. The recommended extent of thyroid surgery in patients with FNAB and cytology of malignant

• A tumor larger than 4 cm, or with a gross extrathyroidal extension, or clinically metastatic lymph nodes or proven distant metastases, requires a total or near-total thyroidectomy as

• For tumors >1 cm and < 4 cm without extrathyroidal invasion, with no clinical data of lymph node metastases, the initial surgical procedure can be either bilateral (total or neartotal thyroidectomy) or unilateral (lobectomy). Lobectomy may be sufficient for low-risk papillary and follicular carcinomas. Total thyroidectomy (TT) can be considered by the treatment team, especially if consequent radioiodine ablation (RAI) is planned. TT also enables a reliable follow-up, since thyroglobulin used as a tumor marker is expected to be

• For tumors <1 cm (small, unifocal and intrathyroidal carcinoma), without extrathyroidal extension and without lymph nodes involvement, thyroid lobectomy is sufficient unless there are other indications to remove the contralateral lobe as concurrent Graves' disease

• Therapeutic central-compartment (level VI) lymph dissection of the neck is recommended in addition to the total thyroidectomy for patients with clinical evidence of involved central

• Prophylactic central-compartment neck dissection should be considered in patients with PTC with no clinical data on central neck LNs' involvement in cases that lateral neck nodes

to therapy (see Section 5 on the follow-up of patients with DTC).

cancer), external beam radiotherapy to the neck is also indicated.

thyroid nodule (not medullary carcinoma) depends on the nodule size:

undetectable if the thyroid is removed.

*4.1.2. Lymph node dissection*

lymph nodes [5].

or benign nodules in the contralateral lobe [5, 52].

are involved or when the primary tumor is advanced (T3 or T4).

initial surgical intervention in order to remove all primary tumor mass [5].

**4. Treatment**

**4.1. Surgery**

*4.1.1. Thyroid surgery*

**The initial risk stratification** is based on the TNM staging, as well as the type of tumor histology. ATA guidelines from 2015 proposed some additional prognostic variables as the extent of lymph node involvement presented as the number and size of lymph metastases, mutational status and degree of vascular invasion as the number of affected vessels that were not present in previous stratification systems (**Table 3**).


**Table 3.** Initial risk stratification (adapted from ATA 2015 guidelines [5]).

**Ongoing (dynamic) risk stratification** reflects the changes of recurrence risk during the follow-up period, which depends on the natural history of the disease and the patient's response to therapy (see Section 5 on the follow-up of patients with DTC).
