1.What is thyroid cancer and how is it related to thyroid nodules?
Thyroid nodules are abnormal masses of thyroid gland found by self-examination, clinical doctor’s palpation or by ultrasound or CT examination. Nodules are classified according to their causes: inflammation, benign tumor, malignant tumor, etc. Thyroid cancer is a special kind of thyroid nodule, which is the most dangerous disease to human body because it is a malignant tumor with invasive growth characterized by genetic mutation and out of the body’s immune monitoring.
2.What are the symptoms of thyroid cancer?
Early thyroid cancer may not have any symptoms and is often detected by physical examination. In advanced thyroid cancer, due to invasion of adjacent tissues or distant metastasis, clinical symptoms may appear: for example, local hard lumps may be palpable in the primary lesion of thyroid gland or metastasis of lymph nodes in the neck; tumor invading the recurrent laryngeal nerve may lead to hoarseness; tumor invading the trachea may lead to hemoptysis or whistling disorder; tumor invading the esophagus may lead to difficulty in swallowing; tumor metastasis to bone may lead to pain; tumor metastasis to lung may lead to hemoptysis or chest fluid. Tumor bone metastasis can lead to pain; tumor lung metastasis can lead to hemoptysis or pleural fluid and other manifestations.
3.What are the tests for thyroid cancer?
Physical examination (physical examination), ultrasound, CT and MRI, FNA (fine needle aspiration cytology), etc. are commonly used. Ultrasound is currently the first choice for thyroid cancer screening, which is non-invasive, highly accurate, reproducible and inexpensive. The accuracy of ultrasound can reach 85%, while CT and MRI are more important for thyroid cancer with extensive invasion or lymph node metastasis in the neck, especially for determining the involvement of adjacent organs and the relationship between lymph nodes and blood vessels, which is essential for surgical treatment. Currently, FNA is the most accurate preoperative test, with a diagnostic accuracy of 90%. However, for follicular tumors or larger tumors, the accuracy decreases. For such tumors, intraoperative frozen pathology is more meaningful.
4.Will patients with thyroid cancer have any abnormalities in biochemical indicators?
Thyroid cancer is a change in the biological properties of some tissues of the thyroid gland. The remaining tissues can still maintain normal physiological functions, so thyroid cancer patients can often have normal thyroid function tests. On the other hand, thyroid gland is an endocrine organ and thyroid cancer can show some characteristics of endocrine tumors, such as the relationship with estrogen, calcitonin, carcinoembryonic antigen (CEA), tumor-specific growth factor (TGSF) and thyroglobulin (Tg). The abnormalities of these indicators can suggest the presence of tumor, but cannot be used as a basis for diagnosis.
5.What are the characteristics of the development of thyroid cancer? What are the factors associated with it?
Thyroid cancer is one of the most common malignant tumors of the endocrine system, and its incidence has been increasing year by year in many countries and regions in recent years, becoming one of the malignant tumors of great concern. The incidence of thyroid cancer in women is about three times higher than that in men.
It is generally believed that thyroid cancer is the result of a combination of genetic factors, environmental factors, ionizing radiation, psychosocial factors and psychiatric conditions, but its exact pathogenesis is still unclear. One of the more definite factors is the exposure to ionizing radiation during early childhood. Therefore, we cannot prevent the occurrence of thyroid cancer now.
6.The relationship between thyroid cancer and iodized salt, is it possible to eat seafood after thyroid cancer surgery?
There is no clear scientific evidence that salt iodization or excessive iodine intake is directly related to the occurrence of thyroid tumor. Studies have shown that prolonged high or low iodine intake can lead to overproduction of thyroid stimulating hormone by the pituitary gland, which can lead to significant hyperplasia of thyroid follicular epithelial cells, causing goiter and eventually mutation into thyroid cancer. In plain areas, there is no lack of iodine under normal diet, so you can use some low iodized salt or non-iodized salt moderately. If you like to eat seafood, you can continue to eat it after surgery, because the current research cannot confirm a direct relationship between seafood and the development of thyroid cancer.
7.What are the pathological types of thyroid cancer?
Thyroid cancer is a malignant tumor that originates from follicular and parafollicular cells of the thyroid gland. There are 4 types of pathological types:
① papillary thyroid carcinoma (PTC).
(2) Follicular thyroid cancer (FTC).
(iii) Undifferentiated thyroid cancer.
Medullary thyroid carcinoma (MTC). Among them, PTC and FTC are called differentiated thyroid cancer (DTC), which accounts for more than 90% of all thyroid cancers and has a 30-year survival rate of more than 90%. There are some rare types of thyroid cancer, such as squamous carcinoma and lymphoma. Among them, undifferentiated thyroid cancer, which is the most malignant, is usually found to be advanced and difficult to have a chance of surgery, with a survival period of about 6 months. Therefore, the pathological types of thyroid cancer include papillary carcinoma and follicular carcinoma, which have good prognosis, as well as undifferentiated carcinoma, which has the most rapid growth and the worst prognosis.
8.What are the treatment methods for differentiated thyroid cancer (DTC)?
At present, the main treatments for DTC patients at home and abroad include surgery, thyroid stimulating hormone (TSH) suppression therapy and iodine-131 internal radiation therapy, while molecular targeted therapy, radiation therapy and biologic therapy are also developing rapidly in recent years.
9.What surgical procedures are available for differentiated thyroid cancer (DTC)?
Standard surgical treatment is still the most effective and simple way to treat DTC, and there are two types of surgical methods: traditional open and minimally invasive (lumpectomy, robotics).
Traditional open surgery is currently the mainstream approach for thyroid cancer. A 3-20 cm long “collar” incision is made in the neck using the transverse neck line to remove the diseased tissue including the thyroid gland and surrounding metastatic lymph nodes. The advantage of this approach is that it facilitates the management of larger primary thyroid cancer lesions and lateral cervical lymph nodes that are tightly adherent to blood vessels and have cystic changes, which are more difficult to manage during lumpectomy and robotic surgery. The disadvantage is that it leaves a more obvious scar in the exposed part of the neck. Despite the use of fine subcutaneous and skin alignment, intracutaneous continuous sutures and other cosmetic plastic surgery methods in our surgery, some scarring is slight due to the different body types of patients, but some scarring can also be hyperplastic, resulting in more obvious scarring. Female patients who are young and have limited lesions often struggle with these scars as they gradually recover from the blows of surgery.
In recent years, the use of endoscopic and robotic techniques in the field of thyroid treatment has developed rapidly. Endoscopically assisted removal of not only the thyroid lobes but also the central thyroid area and lateral cervical lymph nodes is possible, allowing both complete removal of the lesion and cosmetic, minimally invasive features, and is playing an increasingly important role in the treatment of DTC. Compared with traditional open surgery, robotic thyroid surgery is more complete, with smaller and more aesthetic incisions, less damage to the nerves and blood vessels around the thyroid gland, and faster postoperative recovery. However, the high cost of surgery is its biggest drawback, which restricts the promotion of clinical use.
There are still some questions about lumpectomy and robotic surgery. The main questions are whether the lesion can be cut and the size of the trauma. In fact, any surgical procedure is a “mega-invasive” procedure in the hands of an unskilled or uninformed surgeon. When a surgeon has mastered the lumpectomy technique and the local anatomical features around the thyroid gland, the lumpectomy technique becomes a truly minimally invasive surgical approach. Due to the unique magnification of the lumpectomy, tiny bleeding spots, the recurrent laryngeal nerve, parathyroid glands, lymph nodes and other structures can be clearly detected. Sometimes when using lumpectomy for radical thyroid cancer treatment, a piece of gauze cannot get wet and a bloodless operation can be achieved completely. In recent lumpectomies, we also usually do not routinely place drains because of the minimal trauma and minimal exudation. This allows patients to be more comfortable postoperatively and also further reduces scarring. For some thyroid cancers that do not have heavy lateral neck metastases and no cystic changes in the lymph nodes, lumpectomy is a good option. Just like 20 years ago, gallbladder surgery was done openly, but nowadays, even in primary care hospitals, lumpectomy to remove the gallbladder is a necessary basic skill. The lumpectomy thyroid cancer surgery is done to remove the tumor with precision while achieving a completely scarless neck. It is especially suitable for women who are unmarried and have high aesthetic requirements and quality of life.
10.What is the extent of resection for differentiated thyroid cancer (DTC)? Is it necessary to perform lymph node dissection in the neck?
Since the prognosis of DTC is very good, it should be equally important to cure the tumor and to give the patient a good quality of life. As a specialist in head and neck surgery, one should have a better understanding of the thyroid than other specialties. Simply put, thyroid surgery is dealing with 2 parathyroid glands (superior and inferior thyroid glands), 2 vessels (superior and inferior thyroid arteries), and 2 nerves (recurrent laryngeal nerve, lateral branch of superior laryngeal nerve). For low-risk thyroid cancer, lobe and isthmus resection is a minimal scope. In contrast, for higher risk thyroid cancer, total bilateral lobectomy of the thyroid should be performed. Near-total thyroidectomy and subtotal thyroidectomy, which were used in the past, should be eliminated. If the thyroid is not cut cleanly, it is not good for postoperative treatment. For one thing, once the recurrence of localization occurs, it is difficult to preserve the recurrent laryngeal nerve and parathyroid glands. Another is that if Iodine-131 treatment is performed in the future, it will be very difficult to deal with the more residual thyroid tissue. A good thyroid specialist should have the ability to completely remove the thyroid tissue while protecting the 2 parathyroid glands and 2 nerves so that the patient has a low Tg level after surgery.
The general trend has been relatively conservative in terms of whether lymph node dissection should be performed, as detailed in the 2015 ATA guidelines and others. Lymph nodes with clear clinical metastases should be treated without mercy, as surgery is the easiest and most effective way to deal with these lymph nodes. However, lymph nodes that are not clinically proven to have metastases, especially those that are only ultrasonically detected but not definite, must be treated differently. The author once met a young patient who underwent total thyroidectomy + bilateral lymph node dissection in area VI + lymph node dissection in areas II, III and IV of the lateral neck according to the ultrasound report “multiple lymph nodes in areas III and IV of the lateral neck, closely related to the internal jugular vein, the largest of which is 1.7 cm*0.5, with unclear demarcation between the skin and the medulla, considered to be abnormal lymph nodes. Postoperative pathology: papillary thyroid carcinoma with surrounding Hashimoto’s thyroiditis changes; no metastasis in lateral cervical lymph nodes (0/17). A more careful evaluation or observation period might have prevented such a major surgery, leaving a long scar in the patient’s neck. Especially when thyroid cancer combined with thyroiditis is most common in patients with reactive hyperplasia of lymph nodes, then it is important to consider carefully how extensive the debulking should be performed. It is important not to be either too conservative or too extensive. After all, DTC has a good prognosis and a slow growth rate. Under the premise of standardizing the removal of the primary thyroid lesion, the lateral cervical lymph nodes that cannot be clinically identified can be completely further followed up so that the patient can spend the best youthful years of his life, and then determine whether further surgery is needed during the follow-up process. It is completely too late to determine the lymph nodes that are metastatic before doing surgery.
11.What is the principle of iodine therapy for differentiated thyroid cancer (DTC)? Under what circumstances is iodine therapy necessary?
The main function of the thyroid gland is to take iodine from the body (mainly from our diet) and then use it to synthesize thyroid hormones in the thyroid gland for our body to use. Papillary carcinoma and follicular thyroid cancer are the most common types of thyroid cancer. The common feature of these two types of cancer is that they can absorb iodine and synthesize thyroid hormones. When the cancerous tissue absorbs iodine-131, it can kill the thyroid cancer cells.
Since iodine therapy is effective for DTC, do all thyroid cancers need to have iodine therapy after surgery? The answer is no. The indications for iodine therapy emphasize the need for iodine therapy in patients with high risk factors, while iodine therapy is not required for low risk patients without indications. Indications for iodine-131 therapy include.
(1) Those with distant metastases and iodine uptake.
(2) Those with localized lesions that cannot be completely removed.
(3) Lymph node metastasis or cancer embolism, or invasion of the outer envelope.
(4) Multiple cancer foci with all foci <1 cm in diameter and no other high-risk factors, or a single lesion with a maximum diameter <1 cm; any DTC including follicular carcinoma, as long as there are no other risk factors such as lymph node metastasis, perineural invasion, vascular invasion or distant metastasis, and no residual thyroid gland, there is no need for iodine-131. Some other cases need to be systematically evaluated. Overall, only a small percentage of DTCs require iodine-131 treatment after standard surgical treatment. Adverse effects and potential harms of iodine therapy include short-term mild gastrointestinal discomfort, nausea, vomiting, nausea and swelling and painful sensation in the neck after treatment; a small percentage cause more serious toxic side effects such as laryngeal edema, impaired salivary gland function, radiation cystitis, hair loss, bone marrow suppression and gonadal suppression, and even fibrosis of the lung.
12.What is the principle of endocrine suppression therapy for differentiated thyroid cancer (DTC) and how much TSH should be controlled?
The main regulatory mechanism of the thyroid gland is the hypothalamic-pituitary-thyroid self-regulatory system. The pituitary thyrotropin (TSH) is the most important of these mechanisms and affects many aspects of thyroid activity, especially the synthesis and secretion of thyroid hormones. It is generally accepted that TSH plays a major role in the development of the thyroid gland. The reason for receiving thyroxine after surgery for papillary and follicular thyroid carcinoma is, on the one hand, to correct hypothyroidism after subtotal or total thyroidectomy. On the other hand moderate intake of thyroxine promotes TSH suppression, reduces the stimulation of residual thyroid cancer tissue by TSH secretion and inhibits the growth and recurrence of tumor. Especially in the high-risk thyroid cancer group, TSH suppression therapy can increase the disease-free survival rate of patients by 2-3 times.
The TSH secretion is suppressed while the thyroid function is maintained as normal. Usually, the TSH concentration is maintained at 0.1-0.5 mU/L, but if the patient is a high-risk patient, the TSH concentration should be maintained at less than 0.01 mu/L. For most patients, it is appropriate to maintain the TSH concentration at 0.1 mU/L or the lower limit of the normal value. The commonly used drug is levothyroxine sodium, which can be extracted from domestic animals or synthesized artificially. The dosage of levothyroxine is 75~150ug/d. The dosage is not the same for each patient because of the different tolerances of different patients, and the maximum amount tolerated by the patient is appropriate. The concentration of T3, T4 and TSH in the blood can be measured to guide the dosage of thyroid preparations.
Side effects of thyroxine application include hyperthyroidism symptoms such as palpitations, excessive sweating, and nervous excitement when the dose is too high. In severe cases, vomiting, diarrhea and fever, and even angina pectoris and heart failure may occur. Therefore, I personally believe that for some low-risk patients with nail cancer, the control of TSH does not necessarily have to be very strict. The dosage method is to be taken daily half an hour before breakfast. Because the metabolism of thyroid hormone is slow, if the dosage is adjusted, it is recommended to recheck the thyroid function after one month. In addition, if patients need iodine therapy, they should stop taking thyroxine tablets 1-2 months before surgery to deplete the thyroid hormones in the body, which can make iodine therapy achieve better results.
13.What is the targeted treatment for thyroid cancer?
Most thyroid cancers can be cured by surgery, iodine-131 internal radiation and thyroid stimulating hormone (TSH) suppression therapy, but there is still a lack of effective treatment for progressive medullary carcinoma, locally advanced radioiodine-refractory thyroid cancer. The use of molecularly targeted drugs for such patients is a major advancement in thyroid cancer treatment in recent years and has shown promising applications.
The progress of molecular biology of thyroid cancer is the basis of targeted therapy, among which the genes that are closely related to the development of thyroid cancer and more representative include ret gene, ras gene, BRAF gene and VEGF gene. Point mutations, gene translocations or abnormal methylation of these genes activate intracellular RAS/MAPK/ERK and PI3K/Akt signaling pathways to promote the development of thyroid cancer. These important discoveries have laid the theoretical foundation for molecular targeted therapy of thyroid cancer and made the scientific application of thyroid cancer biotherapy possible.
14.What do I need to pay attention to after thyroid cancer surgery? How long does it take to recover?
The common complications of thyroid cancer surgery are: bleeding, damage to the recurrent laryngeal nerve, hypoparathyroidism, seroma, lymphatic fistula and infection.
The most common postoperative complication 6-8 hours after surgery is bleeding. Depending on the urgency and amount of bleeding, it can be manifested as increased blood drainage in the drainage tube, wound swelling and petechiae on the skin and subcutis, and early compensatory symptoms of hemorrhagic shock such as palpitations, rapid pulse, and thirst when the bleeding is large. Usually urgent treatment is required to open the wound, find the definite bleeding point and ligate it.
Injury to the recurrent laryngeal nerve can be detected early, and patients experience symptoms such as hoarseness and choking on water immediately after surgery. However, sometimes patients can present with progressive hoarseness after 72 hours due to heat or other causes of injury. This condition usually recovers on its own within 2 weeks-2 months, during which time some B vitamins or hormonal oral medications can be used. Recovery is difficult if the nerve is disconnected, and often requires compensatory contralateral vocal fold overactivity after 3 months, with less volume and a slightly lower voice after recovery.
When the surgery is extensive, temporary hypoparathyroidism can occur, manifested by numbness in the hands and feet, pins and needles sensation around the mouth, and in severe cases, muscle twitching. Immediate calcium supplementation is required, with oral calcium supplementation given in mild cases or intravenous calcium in severe cases. Recovery is usually possible within 1 month. If recovery does not occur beyond 6 months, permanent hypoparathyroidism is defined and requires further evaluation and treatment.
Seroma and lymphatic fistulae often appear 3-5 days after surgery and require appropriate treatment depending on the extent, ranging from puncture and drainage in mild cases to reoperation to close the fistulae in severe cases.
Infections appearing after 5 days postoperatively are extremely rare and are usually secondary to lymphatic fistulae and require anti-inflammatory and cause-specific treatment.
Radical thyroid cancer surgery is a delicate, medium-sized operation, and patients can often heal quickly with a delicate operation. In developed countries, thyroid cancer is often a day surgery, with hospitalization in the morning and discharge in the evening. With minimal trauma and definite hemostasis, it is often possible to eliminate the need for drainage placement, which can significantly reduce scar formation and accelerate wound healing. In the author’s surgery, drainage placement is rarely required.
After full recovery, patients need to come to the clinic for regular review. Tumor surveillance is performed at the same time as TSH adjustment. Due to the slow progression of thyroid cancer, sometimes recurrence of thyroid cancer appears as long as 10 years after surgery, or even longer. Therefore, long term follow-up and monitoring is needed after thyroid cancer surgery.
15.What should I do if new lymph nodes appear during the review of thyroid cancer?
Lymph nodes are immune organs, and there can be up to 8,000 lymph nodes in the whole body. Lymph node hyperplasia is often seen in the head and neck area due to local inflammation and other reasons. There is no need to worry excessively when this happens, as a professional doctor can make a preliminary judgment based on the clinical and imaging examination of these lymph nodes. If the lymph nodes are round and lose their normal target ring structure, showing malignant signs such as punctate calcification, cystic change, and loss of lymph node portal structure, it often indicates the presence of lymph node metastasis, and if identification is difficult, it can also be confirmed by histopathology. Even if lymph node metastasis is present in thyroid cancer, there is usually still a chance for surgical resection and iodine treatment. Most of the lymph nodes can be followed up regularly.