The thyroid gland is an organ located in the midline of the neck, weighs 20-25 grams and has an internal secretion function. The hormone produced by the thyroid gland using iodine plays a role in regulating the whole body metabolism. Thyroid gland diseases are very common in society (approximately 3 out of every 10 people) and usually do not cause symptoms. However, some of the thyroid gland nodules appear as cancer or may later turn into cancer. Its prevalence in the society is 4.2%. The lifetime risk of thyroid cancer in women is approximately 0.7% and in men is 0.25%.
Thyroid cancer is the most common endocrine cancer after ovarian cancer, but it is not a very common disease. However, especially patients with nodules in the thyroid gland should be aware that thyroid cancer may develop. Unlike other cancers, thyroid cancer is a disease that is almost always completely treatable. Thyroid cancers account for less than 1% of all cancer cases. Although it is rare in children, it is among the top 5 cancers seen after the age of twenties. While one in 1000 people develops a thyroid nodule every year, one in 50,000 people develops thyroid cancer.
Thyroid nodules are more common in women than in men, but the incidence of cancer in nodules seen in men is higher than in women.
Ultrasonography is routinely used. In parallel with the increasing rate of thyroid nodule detection with its introduction, the rate of diagnostic approach to these nodules has also increased. More thyroid cancers can be diagnosed with fine needle aspiration biopsy. According to studies, the frequency of thyroid cancer that can be detected incidentally in adults is as high as 6%.
Another important reason why the frequency of thyroid cancers seems to have increased is the detailed pathological examinations of cases operated on for benign thyroid diseases. thin section examination. In this way, the probability of catching thyroid cancer increases from 5% to 13%.
Exposure to radiation of the head and neck area increases the frequency of thyroid cancer. It has been found that the frequency of thyroid cancer increases 20-25 years later in people who received around 200-700 rad radiation in childhood. I did a research It has been shown that the frequency of thyroid cancer is around 2% in people who receive radiation around 500 rad. After the Chernobyl nuclear power plant accident in Russia, there was a great increase in thyroid cancer in people living in that region. Thyroid cancer is 30% more common in cases where radiation was applied years ago for reasons such as acne, scalp problems, tuberculosis in the neck, fungal infections of the scalp, blood vessel tumors of the face, enlarged thymus, tonsillitis, sore throat, chronic cough and excess hair. These types of treatments are no longer applied today.
In addition, the possibility of thyroid nodule and cancer increases in patients who are diagnosed with cancer in the head and neck area and receive radiation to this area. If you have been treated with this type of treatment in the past, you should definitely consult your doctor and ask for the thyroid gland to be examined.
Types of Thyroid Cancer
Thyroid cancers are generally of four types. :
– Papillary
– Follicular
– Medullary
– Anaplastic
85% of thyroid cancers are papillary, follicular or mixed papillary and follicular types. and respond well to treatment. Unlike the rare medullary thyroid cancer, the probability of this type of cancer occurring in the same family members is very low. Since medullary thyroid cancer can be genetically inherited, the presence of nodules in the thyroid glands of family members of these patients should be investigated. Medullary thyroid cancer; It may be associated with simultaneous involvement of other endocrine glands, such as pituitary, adrenal, pancreas and parathyroid glands. This type of involvement is called multiple endocrine neoplasia syndrome. Another rare type of thyroid cancer is anaplastic cancer, which usually has a poor course.
Thyroid Cancer Symptoms and Diagnosis
Thyroid gland cancer usually does not cause symptoms. It may occur in patients who are being followed up for goiter or incidentally during tests performed for another disease. Rarely, neck mass, hoarseness, difficulty swallowing; Very rarely, it may occur with bone fractures or hyperthyroidism (toxic goiter). Facial flushing, diarrhea and fatigue may occur in 30% of patients with medullary cancer.
The person has a thyroid nodule. The most effective method used today to detect whether or not thyroid disease is thyroid ultrasonography. The thyroid scintigraphy method, which was used in the past, is now used to determine activity, not to detect nodules.
In recent years, due to the advancement of diagnostic methods in thyroid diseases and the development of technical facilities, thyroid ultrasonography and fine needle aspiration biopsy can be performed in many cases. For this reason, the possibility of diagnosing even incipient thyroid cancers is very high today. However, it is worth noting that thyroid nodules are detected at a rate of 50% in autopsy studies. In other words, there are still thyroid nodules in the society that cannot be detected even with ultrasound.
After detecting a nodule in the thyroid gland, if there is any doubt, a fine needle aspiration biopsy of the nodule determines whether the thyroid nodules are malignant or not. Fine needle aspiration is a low-risk, fast-yielding, easily applied and inexpensive method in good hands. If the biopsy result is benign and the patient has no other complaints, thyroid nodules can be followed. If the biopsy result is suspicious or malignant, the treatment phase is started.
Thyroid Cancer Treatment
The most effective method of thyroid cancer treatment is surgery. Although in some centers it is thought that removing only a part of the thyroid gland may be sufficient in thyroid cancer, the most reliable method is complete removal of the thyroid gland. This method reduces the possibility of recurrence and maximizes the effectiveness of non-surgical treatment methods such as radioactive iodine therapy after surgery. Complications such as hoarseness and low calcium that may occur in thyroid surgery are minimized when the surgery is performed by an experienced team.
In up to 80% of cases, cancer can spread from the thyroid gland to neighboring lymph nodes. However, a small number of them show clinical symptoms. When such a finding occurs, the lymph nodes in question must also be surgically removed. There is no need to perform a neck dissection for lymph nodes that do not show clinical findings in a patient with thyroid cancer.
Based on the findings during surgery, the pathological data of the cancer, and the results of whole body scans performed after total thyroidectomy. After surgery, patients may receive radioactive iodine treatment. Radioactive iodine treatment is usually given once in capsule or liquid form, 6 weeks after the required surgery. In order for radioactive iodine treatment to be effective, the patient is not given thyroid hormone for a while after the surgery and TSH values are increased. After radioactive iodine treatment, patients must receive thyroid replacement therapy (thyroid tablets).
Radioactive iodine treatment is simple, but may require a certain period of stay in the hospital depending on the dosage. Although neck discomfort, decreased salivation, and changes in taste may occur, generally no significant side effects occur. Sometimes this treatment may be repeated if residual or recurrent thyroid cancer is detected.
If the thyroid cancer cannot be completely removed, external cobalt radiation therapy may be necessary, especially in Hurtle cell cancer, medullary or anaplastic thyroid cancer. External radiation therapy involves treating the neck area with small reduced doses over a period of approximately 4-6 weeks and does not cause any side effects other than minor skin reactions.
Post-Treatment Follow-Up
Following surgery and radioactive iodine treatment, patients start taking thyroid hormone tablets. However, this is also valid for benign thyroid patients who have not undergone surgery. In other words, people with thyroid disease or who have undergone surgery due to goiter generally need to take thyroid tablets externally.
Thyroid hormone tablets not only meet the need for thyroid hormone in the body, but also suppress the pituitary gland and prevent the secretion of thyrothyropine from this gland. Thus, it prevents the development of possible thyroid cancer cells. Thyroid functions are checked with routine thyroid function tests and clinical and laboratory tests. Thyroid cancer patients are investigated for recurrence of cancer in 6 to 12 month periods. Measurement of serum thyroglobulin level is the best method to investigate the development of recurrent cancer. Additionally, neck ultrasonography and chest radiography can also help determine whether the cancer has recurred.
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