In recent years, with the change in public health awareness and the popularity of high-resolution ultrasonography, thyroid nodules have become one of the most common clinical thyroid disorders. According to statistics, at least one thyroid nodule can be found in 4% to 7% of people with no clinical symptoms, and the chance of finding a thyroid nodule on ultrasound is about 17% to 27%, and may be even higher. Most thyroid nodules are benign, but about 5% are malignant.
Early detection and identification of benign and malignant nodules are important for the selection of clinical treatment and prediction of treatment outcome.
Preoperative differential diagnosis of thyroid nodules mainly includes ultrasonography and ultrasound-guided cytopathological examination by fine needle aspiration. Signs of ultrasound-suspected thyroid cancer mainly include.
(1) Significant hypoechogenicity of the nodule;
(2) Nodules with poorly defined borders, irregular margins and protruding envelope;
(3) Echo disorder in the nodule;
④There are small gravel-like calcifications;
(⑤) Rich blood supply in the nodule;
(6) The anterior-posterior diameter of the nodule cross-section is greater than the left-right diameter;
(7) Metastatic lymph nodes in the neck. If the nodule has more than three signs above, thyroid cancer should be highly suspected and surgery or further fine needle aspiration should be performed promptly. Ultrasound-guided cytopathological examination with fine needle aspiration can confirm the diagnosis of thyroid cancer in some patients before surgery to a certain extent and save some patients from unnecessary surgical treatment.
The gold standard for thyroid cancer diagnosis is pathological examination, and thyroid cancer is classified into differentiated and undifferentiated types according to histology. Differentiated thyroid cancer is subdivided into papillary thyroid cancer and follicular thyroid cancer. According to the possibility of tumor recurrence, differentiated thyroid cancer is classified into low-risk and high-risk types. Age at onset <45 years, tumor diameter <1.0 cm, and no evidence of intra- or extra-thyroidal spread are classified as low-risk type, accounting for 85% of thyroid cancer; age at onset >45 years, tumor diameter >1.0 cm, and evidence of peripheral lymph node involvement and distant metastasis are classified as high-risk type.
The American Thyroid Association guidelines for the treatment of thyroid cancer propose a three-step process for the radical treatment of differentiated thyroid cancer: surgery + postoperative 131I therapy + thyroid hormone replacement therapy. The guidelines state the criteria for clinical cure of differentiated thyroid cancer.
① No clinical evidence of tumor presence;
②No imaging evidence of tumor presence;
③No uptake of 131I in the thyroid bed and extra-bed tissues on 131I whole body imaging after thyroid clearing therapy;
④Serum Tg (thyroglobulin) was not measured in the absence of TGAb (thyroglobulin antibody) interference in the case of thyroid hormone suppression therapy and in the case of TSH stimulation.
Surgery: Nodules with a high probability of malignancy suggested by ultrasound or nodules with a diameter of more than 1.5 cm should be surgically removed. Postoperative pathology confirms the benign and malignant nature of the nodule. Malignant nodules require further treatment.
Postoperative 131I therapy: Patients with postoperative pathologically confirmed differentiated thyroid cancer should undergo 131I therapy to further remove residual thyroid and metastases, which is an effective means to prevent residual or recurrence of thyroid cancer and to prevent and treat metastases. Depending on the patient’s condition and surgery, patients with malignant thyroid cancer without distant metastases can generally be clinically cured with 1-3 times of postoperative 131I treatment.
Thyroid hormone replacement therapy: Patients with differentiated thyroid cancer who undergo total thyroidectomy have insufficient thyroid hormone secretion and need exogenous supplemental replacement therapy to achieve the purpose of correcting hypothyroidism and inhibiting the recurrence or metastasis of lesions.
After each 131I treatment, the next treatment plan will be drawn up according to the patient’s condition, surgery and the results of 131I whole body scan. 131I treatment interval is about 3~6 months, thyroid hormone is stopped 2~4 weeks before 131I treatment, low iodine diet for 1 month after discharge from 131I treatment, and free thyroid function and two thyroid tumors (Tg, TGAb) are reviewed regularly. Patients who have reached clinical cure should still be reviewed regularly and have neck ultrasound and 131I whole body scan at appropriate times, and keep taking thyroid hormone for a long time.