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Thyroid Cancer. What is The Thyrid Gland?. The thyroid gland is a butterfly-shaped endocrine gland that is normally located in the lower front of the neck. The thyroid’s job is to make thyroid hormones, which are secreted into the blood and then carried to every tissue in the body.
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What is The Thyrid Gland? • The thyroid gland is a butterfly-shaped endocrine gland that is normally located in the lower front of the neck. • The thyroid’s job is to make thyroid hormones, which are secreted into the blood and then carried to every tissue in the body. • Thyroid hormone helps the body use energy, stay warm and keep the brain, heart, muscles, and other organs working as they should.
Incidence of thyroid cancer Although thyroid cancer is considered a rare neoplasm, it is the most common endocrine malignancy and epidemiological studies report a progressive increase in the incidence of thyroid carcinoma in the last twenty years.
What is a Thyroid nodule? • The term thyroid nodule refers to an abnormal growth of thyroid cells that forms a lump within the thyroid gland. • Although the vast majority of thyroid nodules are benign (noncancerous),a small proportion of thyroid nodules do contain thyroid cancer
What are the symptoms of a Thyroid nodule? • Most thyroid nodules do not cause symptoms. • Often, thyroid nodules are discovered incidentally during a routine physical examination or on imaging tests like CT scans or neck ultrasound done for completely unrelated reasons.
What are The symptoms of a Thyroid nodule? • Occasionally, patients themselves find thyroid nodules by noticing a lump in their neck while looking in a mirror, buttoning their collar, or fastening a necklace. • Abnormal thyroid function tests may occasionally be the reason a thyroid nodule is found. Thyroid nodules may produce excess amounts of thyroid hormone causing hyperthyroidism
What are The symptoms of a Thyroid nodule? • However, most thyroid nodules, including those that cancerous, are actually non-functioning, meaning tests like TSH are normal. • Rarely, patients with thyroid nodules may complain of pain in the neck,jaw, or ear.
What are The symptoms of a Thyroid nodule? • If a nodule is large enough to compress the windpipe or esophagus, it may cause difficulty with breathing, swallowing, or cause a “tickle in the throat”. • Even less commonly, hoarseness can be caused if the nodule invades the nerve that controls the vocal cords but this is usually related to thyroid cancer.
What are The symptoms of a Thyroid nodule? The important points: • Thyroid nodules generally do not cause symptoms. • Thyroid tests are most typically normal even when cancer is present in a nodule.
Definition • A risk factor is anything that affects a person’s chance of getting a disease such as cancer. • Different cancers have different risk factors. • Some risk factors, like smoking, can be changed. Others, like a person’s age or family history, can’t be changed.
But risk factors don’t tell us everything. • Having a risk factor, or even several risk factors, does not mean that you will get the disease. And many people who get the disease may have few or no known risk factors. • Even if a person with thyroid cancer has a risk factor, it is very hard to know how much that risk factor may have contributed to the cancer.
Scientists have found a few risk factors that make a person more likely to develop thyroid cancer.
Thyroid cancer risk factors • Gender and age • For unclear reasons thyroid cancers (like almost all diseases of the thyroid) occur about 3 times more often in women than in men. • Thyroid cancer can occur at any age, but the risk peaks earlier for women (who are most often in their 40s or 50s when diagnosed) than for men (who are usually in their 60s or 70s).
Thyroid cancer risk factors A diet low in iodine • Follicular thyroid cancers are more common in areas of the world where people’s diets are low in iodine. In the United States, most people get enough iodine in their diet because it is added to table salt and other foods. • A diet low in iodine may also increase the risk of papillary cancer if the person also is exposed to radioactivity.
Thyroid cancer risk factors Radiation • Exposure to radiation is a proven risk factor for thyroid cancer. • Sources of such radiation include certain medical treatments and radiation fallout from power plant accidents or nuclear weapons.
Thyroid cancer risk factors • Having had head or neck radiation treatments in childhood is a risk factor for thyroid cancer. • Risk depends on how much radiation is given and the age of the child. • In general, the risk increases with larger doses and with younger age at treatment. Before the 1960s, children were sometimes treated with low doses of radiation for things we wouldn’t use radiation for now, like acne, fungus infections of the scalp (ringworm), or enlarged tonsils or adenoids.
Thyroid cancer risk factors • Radiation therapy in childhood for some cancers such as lymphoma, Wilms tumor, and neuroblastoma also increases risk. • Thyroid cancers that develop after radiation therapy are not more serious than other thyroid cancers.
Thyroid cancer risk factors • Imaging tests such as x-rays and CT scans also expose children to radiation, but at much lower doses, so it’s not clear how much they might raise the risk of thyroid cancer (or other cancers). • If there is an increased risk it is likely to be small, but to be safe, children should not have these tests unless they are absolutely needed.
Thyroid cancer risk factors • Several studies have pointed to an increased risk of thyroid cancer in children because of radioactive fallout from nuclear weapons or power plant accidents. • For instance, thyroid cancer was many times more common than normal in children who lived near Chernobyl, the site of a 1986 nuclear plant accident that exposed millions of people to radioactivity. Adults involved with the cleanup after the accident and those who lived near the plant have also had higher rates of thyroid cancer. Children who had more iodine in their diet appeared to have a lower risk.
Thyroid cancer risk factors • Some radioactive fallout occurred over certain regions of the United States after nuclear weapons were tested in western states during the 1950s. This exposure was much, much lower than that around Chernobyl. A higher risk of thyroid cancer has not been proven at these low exposure levels.
Thyroid cancer risk factors • Being exposed to radiation when you are an adult carries much less risk of thyroid cancer.
Thyroid cancer risk factors Hereditary conditions and family history • Several inherited conditions have been linked to different types of thyroid cancer, as has family history. • Still, most people who develop thyroid cancer do not have an inherited condition or a family history of the disease.
Thyroid cancer risk factors Medullary thyroid cancer • About 1 out of 3 medullary thyroid carcinomas (MTCs) result from inheriting an abnormal gene.
In these inherited forms of MTC, the cancers often develop during childhood or early adulthood and can spread early. MTC is most aggressive in the MEN 2b syndrome.
If MEN 2a, MEN 2b, or isolated FMTC runs in your family, you may be at very high risk of developing MTC. Ask your doctor about having regular blood tests or ultrasound exams to look for problems and the possibility of genetic testing
Can thyroid cancer be prevented? • Most people with thyroid cancer have no known risk factors, so it is not possible to prevent most cases of this disease.
Thyroid cancer in Iran • The cancer shows considerable ethnic and geographic variation and the highest incidence rates are reported in areas of high iodine intake. • On the other hand, the prognosis of cancer is worse in endemic goiter regions compared to countries with adequate iodine supply. • Some authors have suggested that this may be partly due to higher rates of undifferentiated thyroid cancers, but no consensus is existing on the issue.
Thyroid cancer in Iran • In Iran, thyroid cancer has been reported in 1 year to 80 years old patients. • In TUMS study, mean age of Iranian patients was 42.8±0.9 with male patients being markedly older. • Patients affected by the anaplastic type were older at the time of diagnosis, a finding in agreement with the worse prognosis of this type of thyroid cancer.
Thyroid cancer in Iran • Thyroid cancer is more common among women. • The female to male ratio of Iranian patients in TUMS study was 1.8. This ratio was 1.3 in anaplastic carcinomas due to the higher proportion of males affected. • This finding that has been reported in other series, which may partly describes the worse prognosis of cancer among men
Thyroid cancer in Iran • Thyroid gland is extremely radiosensitive, which has been ascribed to its superficial site, its high degree of oxygenation and the high rate of cell division. • Currently, a multicenteric project is being conducted to evaluate the effect of high background radiations on thyroid nodularity and thyroid function of women living in the HLRA of Ramsar.
Thyroid cancer in Iran • In formerly iodine deficient regions, where iodine supplementation has been introduced, increased proportion of papillary histology has been accompanied with decreased numbers of anaplastic types.
Thyroid cancer in Iran • In the TUMS study, the most common clinical presentation (initial manifestation) was a central neck mass. • 28.6% of the tumors had metastasized, most frequently to the cervical lymph nodes, by the time the patient presented.
Thyroid cancer in Iran • Iran was an endemic goiter area with clear indications of iodine deficiency.
Thyroid cancer in Iran • Against expectation for an iodine-deficient area, where FTC (follicular thyroid carcinoma)is more common, TUMS findings did not reflect this and the distribution of tumors in that study was closer to what seen in iodine rich areas with papillary and follicular types accounted for 79.7% and 8.8% of cases, respectively
Thyroid cancer in Iran • Papillary carcinomas have much better prognosis than follicular types and even some authors believe thatpatients with papillary cancer may survive the same as general population.
Thyroid cancer in Iran • It seems that as long as endemic goiter is a frequent feature in a population, patients are not worried about goiterous growth until serious symptoms occur. By that time, small well- differentiated thyroid carcinomas have been replaced by larger less-differentiated types
Presenting Signs and Symptoms in 1177Patients Diagnosed with Carcinoma of the Thyroid in Iran.
Increased incidence of thyroid cancer? • physicians might be identifying small cancers that would have been overlooked in earlier decades and the almost stable death rate supports this point of view. • Small papillary cancer makes up almost all of the increase in cases. • The prognosis is good and 6% of patients die from the cancer
How is a Thyroid nodule evaluated? • Once the nodule is discovered, your doctor will try to determine whether the rest of your thyroid is healthy or whether the entire thyroid gland has been affected by a more general condition such as hyperthyroidism or hypothyroidism.
How is a Thyroid nodule evaluated? • Your physician will feel the thyroid to see whether the entire gland is enlarged and whether a single or multiple nodules are present. • The initial laboratory tests may include measurement of thyroid hormone (thyroxine, or T4) and thyroid-stimulating hormone (TSH) in your blood to determine whether your thyroid is functioning normally.
How is a Thyroid nodule evaluated? • Since it’s usually not possible to determine whether a thyroid nodule is cancerous by physical examination and blood tests alone, the evaluation of the thyroid nodules often includes specialized tests such as thyroid ultrasonography and fine needle biopsy.
Thyroid Sonography: • Thyroid ultrasound is a key tool for thyroid nodule evaluation. It uses high-frequency sound waves to obtain a picture of the thyroid. This very accurate test can easily determine if a nodule is solid or fluid filled (cystic), and it can determine the precise size of the nodule.
Thyroid Sonography: • Ultrasound can help identify suspicious nodules since some ultrasound characteristics of thyroid nodules are more frequent in thyroid cancer than in noncancerous nodules. • Thyroid ultrasound can identify nodules that are too small to feel during a physical examination.
Thyroid Sonography: • Ultrasound can also be used to accurately guide a needle directly into a nodule when your doctor thinks a fine needle biopsy is needed. • Once the initial evaluation is completed, thyroid ultrasound can be used to keep an eye on thyroid nodules that do not require surgery to determine if they are growing or shrinking over time.
