I. What is thyroid cancer?
Thyroid carcinoma, the most common malignant tumor of thyroid gland, is a malignant tumor that originates from the epithelial cells of thyroid gland.
What are the clinical manifestations of thyroid cancer?
As thyroid cancer has different pathological types and biological characteristics, its clinical manifestations also vary. Most of them are asymptomatic, but occasionally a nodule or lump is found in the anterior neck area. In some cases, the mass has been present for many years and has only recently increased in size or metastasized. Local signs also vary, from asymmetric nodules or masses in the thyroid gland to masses within the gland that move up and down with swallowing. When the surrounding tissues or trachea are invaded, the mass will be fixed.
What are the types of thyroid cancer?
Most of the pathological types are differentiated thyroid cancer, including papillary and follicular adenocarcinoma. If treated properly, the prognosis of differentiated thyroid cancer is very good, with a 10-year survival rate of over 90%.
In 2012, a study found that the incidence of thyroid cancer in women has jumped to the fifth most common tumor in women. Except for medullary carcinoma, most thyroid cancers originate from follicular epithelial cells and can be classified into papillary carcinoma (60%), follicular carcinoma (20%), undifferentiated carcinoma (15%), and medullary carcinoma (7%) according to the pathological type. Among them, papillary carcinoma has early metastasis to cervical lymph nodes, but the prognosis is better; follicular carcinoma is fast-growing, moderately malignant and easily metastasized by blood transport; undifferentiated carcinoma has a poor prognosis, with an average survival time of 3-6 months.
What are the treatment methods of thyroid cancer?
1.Surgical treatment
(1) Treatment of suspected thyroid cancer nodules: A more reasonable plan is to perform screening and routinely do 131Ⅰ scan on all thyroid nodules. Except for the functional or inflammatory nodules shown on 131Ⅰ scan, surgical exploration is used. Early surgical treatment is particularly indicated in those with the following conditions
①Not excluding cancerous nodules.
(ii) Cystic nodules larger than 3-5 cm in diameter, or those with cancer cells found by puncture examination or not disappearing after 2 to 3 punctures.
③Substantial masses on ultrasonography. As for the choice of surgical procedure for solitary nodule, due to the high incidence of solitary nodule cancer, which can reach 5% to 35%, there is no reliable method to determine it so far, and even intraoperative frozen section examination has individual missed diagnosis, and the postoperative recurrence rate is high after simple nodule removal. It can reach 16.7%. Therefore, we routinely perform lobectomy plus isthmus resection for single solid thyroid nodules, cystic solid nodules and cystic nodules >4 cm, and do not give neck clearance for those with no intraoperative lymph node enlargement.
(2) The rules of treatment for diagnosed thyroid cancer depend on the patient’s physical condition, the pathological type and clinical stage of the cancer.
(1) Papillary carcinoma: clinically, it has the characteristics of low malignancy, high rate of cervical lymph node metastasis, and prevalence in young and middle-aged women, so surgical treatment must take these factors into consideration. If the cancer is confined to one side of the gland, the affected side of the gland together with the isthmus can be excised, and the opposite side of the gland can be excised at the same time. However, if the cancer has invaded the left and right lobes, the gland on both sides, together with the isthmus, should be completely removed. The cure rate can be more than 80% after 5 years of surgery. Clinical practice proves that it is not necessary to remove the affected cervical lymph nodes at the same time for papillary adenocarcinoma without cervical lymph node metastasis, and prophylactic cervical lymph node removal cannot improve the cure rate. However, the importance of postoperative follow-up should be emphasized, however, patients in remote mountainous areas or rural areas lacking follow-up conditions should be treated differently. For patients with enlarged lymph nodes in the neck, combined radical thyroid cancer surgery including cervical lymph node dissection is performed, and the protocols are consistent both at home and abroad.
Follicular adenocarcinoma: Although it is a low-grade malignant thyroid cancer, its metastatic mode is mainly hematologic metastasis, and lymph node metastasis accounts for about 20%. Those with cervical lymph node metastasis do not necessarily have bloodway metastasis at the same time, so therapeutic neck dissection is still necessary.
Medullary carcinoma: it is of medium malignancy and often metastasizes along lymphatic tracts and blood channels. Once the lymph nodes in the neck metastasize, it can infiltrate into the outer envelope and involve the surrounding tissues more quickly, so after diagnosis, regardless of whether it can be diagnosed clinically or not, it may affect the smooth operation due to the high blood pressure of the larvae.
Undifferentiated carcinoma: Because of the short course and rapid progress of the disease, most of them have lost the chance of radical treatment at the time of first diagnosis, and the prognosis is poor, so they should not be treated surgically or only biopsy can be done to clarify the diagnosis. However, occasionally there are small lesions that are suitable for surgery, and radical surgery should be actively pursued.
2.Chemotherapy
Differentiated thyroid cancer responds poorly to chemotherapy and is only selectively used in combination with other treatments for some patients with advanced local unresectable or distant metastases. Adriamycin is the most effective, with a response rate of 30% to 45%, which can prolong life and even long-term survival without shrinkage of cancer foci. In contrast, undifferentiated carcinoma is more sensitive to chemotherapy, and combined chemotherapy is mostly used, commonly used drugs, Adriamycin (ADM) cyclophosphamide (CTX), mitomycin (MMC), vincristine.
3.Endocrine therapy
Thyroxine can inhibit the secretion of TSH, thus inhibiting the proliferation of thyroid tissue and well-differentiated carcinoma, and has a better therapeutic effect on papillary and follicular carcinoma. Therefore, routine administration of TSH inhibiting doses of thyroxine after surgery for the above mentioned types of thyroid cancer is effective in preventing cancer with recurrence and metastatic foci, but it is not effective for undifferentiated cancer. In China, 80-120mg of dry thyroid tablets are generally used daily to maintain a high level of thyroid hormone.
4.Radiotherapy
The sensitivity of various types of thyroid cancer to radiation varies greatly, almost proportional to the degree of differentiation of thyroid cancer, the better the differentiation, the worse the sensitivity, and the worse the differentiation, the higher the sensitivity. Therefore, the treatment of undifferentiated carcinoma is mainly radiation therapy. Thyroid cancer has some ability to absorb iodine.
5.What is the prognosis of thyroid cancer?
Compared with cancers of other organs, thyroid cancer has a relatively good prognosis, except for undifferentiated cancer. There are many factors affecting the prognosis, such as the patient’s age, gender, pathological type, the degree of lesion development and whether the treatment is timely and appropriate. Most of the prognosis is related to the combination of these factors.