Anaplastic thyroid cancer is a rare, severe undifferentiated malignant thyroid tumor. It is manifested by pain, dysphagia, difficulty breathing, voice changes, cough, hemoptysis, fever, weight loss, enlargement of the thyroid gland and regional lymph nodes. Sudden rapid growth, germination of nearby organs and rapid metastasis are characteristic. The diagnosis is made on the basis of complaints, anamnestic data, examination results, CT, MRI and cytological examination. Treatment – chemotherapy, radiation therapy. With local tumors, operations are possible. The prognosis is unfavorable.
C73 Malignant neoplasm of the thyroid gland
Anaplastic thyroid cancer (ATC) is a rare oncological disease that usually develops against the background of highly differentiated malignant tumors, benign neoplasms or nodular goiter. According to various data, it ranges from 0.5% to 5% of the total number of ATC. It usually occurs in old age, it is rarely detected in young people. The peak incidence occurs at the age of 65 years. Some scientists believe that anaplastic thyroid cancer is equally common in women and men, others note the predominance of female patients. This form of cancer is considered one of the most aggressive solid tumors. In 40% of patients, metastatic lesion of lymph nodes or distant organs is detected at the first treatment. The prognosis is unfavorable, the average life expectancy is less than 1 year. The treatment is carried out by specialists in the field of oncology and endocrinology.
Cataplastic processes are considered as the main cause of the development of this disease, as a result of which highly differentiated cells undergo reverse development in the process of reproduction and become like low-differentiated forms. During cataplasia, all the main characteristics of cells change: size, structure, chromosome set, biochemical and physico-chemical properties, as well as functional features, with the exception of the reproduction function.
Usually, anaplastic thyroid cancer does not develop from normal, but from already altered organ tissue. The source of an undifferentiated tumor may be a benign neoplasm or a highly differentiated cancer (including a few months or years after radical treatment). Many experts note the previous long (for decades) existence of nodular goiter. Among the factors contributing to the development of the disease are ionizing radiation, contact with carcinogenic substances and immune disorders.
When examining tissue samples of all types of anaplastic thyroid cancer, polymorphism, atypism and a large number of mitoses are detected. Cells characteristic of a particular type of tumor alternate with cells of rounded or irregular shape. There are both large and small cells. Sometimes it is possible to isolate areas of highly differentiated cells in the sample, similar in structure to follicular or papillary carcinoma, which indicates the transformation of one type of cancer into another.
Classification of anaplastic thyroid cancer
There are several classifications of anaplastic thyroid cancer, compiled taking into account the features of the morphological structure of the neoplasm. Larin and Khmelnitsky distinguish 3 types of such tumors: gigantocellular, fusiform and squamous (squamous), also indicating a common combination of intermediate and transitional forms.
- Squamoid anaplastic thyroid cancer is a neoplasm similar to non-cancerous squamous cell carcinoma;
- Fusiform thyroid cancer contains a large number of fusiform cells;
- Giant cell thyroid cancer contains a large number of giant cells.
Along with the listed types of anaplastic cancer, scientists describe other, less common variants of neoplasm, including small-cell, osteoclastic, carcinosarcomatous, lymphoepithelioma-like cancer, etc.
Symptoms of anaplastic thyroid cancer
Usually, patients consult a doctor about a rapidly growing tumor-like formation in the neck. The average period of time between the onset of symptoms and the first visit to a specialist ranges from 1 to 3 months. Three quarters of patients report unpleasant sensations when swallowing. In half of the patients, palpation pains or radiating pains are detected. Less often, hoarseness of voice and difficulty breathing are noted. At the time of the first treatment, 40% of patients with anaplastic thyroid cancer have lesions of regional lymph nodes and distant organs, including lungs (50% of the total number of cases of metastasis), bones (15%) and brain (10%).
On palpation, a dense, lumpy, immobile tumor-like formation is determined. It is possible to damage the skin with the formation of areas of hyperemia and ulceration. Sometimes areas of softening are detected in the area of anaplastic thyroid cancer. In the presence of regional metastases, lymph nodes are enlarged, form immobile conglomerates. In the process of tumor growth, it is possible to merge the primary tumor and the affected lymph nodes into a single conglomerate that captures the entire anterior surface of the neck.
Anaplastic thyroid cancer is characterized by rapid aggressive growth with damage to the muscles, esophagus, trachea, larynx and laryngeal nerve, accompanied by coughing, hemoptysis, pronounced difficulty breathing and eating. In some cases, the neoplasm spreads below the jugular tenderloin and is partially located behind the sternum, affecting the mediastinal organs. Experts note that the cause of death of a significant number of patients is not distant metastases, but the germination of vital organs by the primary tumor.
The rapid growth of anaplastic thyroid cancer is accompanied by the appearance of necrosis sites both in the area of oncological lesion and in normal organ tissue. A large amount of thyroxine enters the bloodstream, which causes the appearance of symptoms of hyperthyroidism. Along with thyroxine, toxic decomposition products are absorbed into the blood, provoking fever, weakness, anemia, hyperthermia and other manifestations of cancer intoxication. The patient’s condition is further aggravated by a violation of the functions of various organs that arose as a result of their metastatic lesion.
The diagnosis of anaplastic cancer is established taking into account anamnesis, clinical symptoms and data from additional studies. The examination plan for patients with suspected anaplastic thyroid cancer includes ultrasound of the thyroid gland, neck radiography, CT of the thyroid gland, laryngoscopy, bronchoscopy and gastroscopy. During diagnostic procedures, the prevalence of the oncological process, the nature of the lesion, the degree of compression of the esophagus and trachea are evaluated. To detect distant metastases, chest radiography, skeletal bone scintigraphy, brain CT and other studies are prescribed.
The final diagnosis of anaplastic thyroid cancer is made on the basis of cytological examination of the punctate obtained during a fine needle puncture biopsy of the thyroid gland. The reliability of the study is 80%, in the remaining 20% of cases, undifferentiated cells cannot be detected, the final diagnosis is made taking into account the results of histological examination of the removed neoplasm. Differential diagnosis is carried out with medullary cancer, high-grade lymphomas, metastatic tumors and other neoplasms with a similar structure.
Treatment of anaplastic thyroid cancer
Effective methods of treating this thyroid pathology have not yet been found. Radical removal of the tumor is impossible in most cases, surgical interventions are palliative in nature and are carried out for diagnostic purposes or to reduce the severity of symptoms caused by compression of nearby organs. The most common tactic is combination therapy, which includes external irradiation and chemotherapy, in case of local tumors – in combination with removal of the thyroid gland.
The prognosis is extremely unfavorable. According to various data, the average life expectancy of patients with anaplastic thyroid cancer does not exceed 6-9 months. The cause of death is usually asphyxia due to aggressive tumor growth or bleeding from a decaying neoplasm. 20-35% of patients manage to live one year from the moment of diagnosis. The five-year survival rate is 5-10%.