Central Cervical Dissection for Clinical Node Negative Papillary Thyroid Carcinoma
Central Cervical Dissection for Clinical Node Negative Papillary Thyroid Carcinoma
This study is divided into three stages. In the first stage, the investigators try to explore
 the objective clinical imaging standard of cN0PTC on the basis of previous studies, formulate
 the "clinical imaging standard of cN0PTC", and randomly enroll 2000 patients under the
 premise of meeting the standard to establish the "predictive model of cN0-pN+PTC".

 In the second stage, 2000 patients will be enrolled to test and improve the evaluation
 efficiency of "cN0-pN+PTC prediction model".

 In the third stage, 2 000 patients without lymph node metastasis assessed by "cNo-pN+ PTC
 prediction model" will be randomly divided into experimental group and control group. The
 experimental group will be treated with pCND, while the experimental group will be treated
 without pCND. The central lymph node metastasis probability, the number and size of
 metastatic lymph nodes in the control group will be observed after operation. The two groups
 will be followed up for 5, 10, 15 and 20 years to observe the RFS and OS, so as to further
 evaluate the "cN0-pN+PTC prediction model" scientifically.
Inclusion Criteria:

 -  Phase I and II:

 1. aged 18 to 80 years old;

 2. the primary treatment of patients with unilateral or bilateral PTC;

 3. ultrasound showed that the tumor was localized in the thyroid gland, and the
 maximum diameter of each lesion was less than 4cm;

 4. ultrasonography of cervical VI lymph nodes: the shortest diameter < 4 mm, no
 calcification, no cystic change, no local or global echo enhancement;

 5. CT scan of cervical VI lymph nodes: the shortest diameter < 4 mm, no
 calcification, no cystic change, no enhancement (CT value 40HU or not higher than
 banded muscle level), no cluster distribution;

 6. patients will voluntarily enter the study after informed consent;

 Phase III:

 1. aged from 18 to 80 years old;

 2. ultrasound showed that the tumor was localized in the thyroid gland, and the maximum
 diameter of each lesion was less than 4cm;

 3. Unilateral or bilateral PTC without lymph node metastasis assessed by "cNo-pN+ PTC
 prediction model";

 4. patients will voluntarily enter the study after informed consent.

 Exclusion Criteria:

 -  (1) patients refused to participate in the study; (2) non first operation patients;
 (3) Lateral cervical lymph nodes or distant metastasis; (4) Hashimoto's disease; (5)
 history of neck trauma.