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Thyroid cancer

Thyroid cancer starts when cells in the thyroid gland starts to grow out of control. Out of control growth of cells in the thyroid gland will result into either benign tumor (benign enlargement of thyroid) or malignant tumor (cancer).



Thyroid gland
The thyroid gland is part of the endocrine system, which consists of a collection of glands responsible for producing the body’s hormones. It is a butterfly-shaped gland located in the front of the neck below the voice box (Adam’s apple) and is made up of two halves, called lobes, which lie on left and right side of the windpipe (trachea).

The lobes are connected in the middle by a small band of thyroid tissue known as the isthmus. Behind the thyroid glands are the parathyroid glands. Parathyroid gland involve four tiny glands that produce hormones too. Thyroid gland is made up of two main cells with different functions in thyroid gland. These cells are

• Follicular cells – These are produce thyroid hormones (thyroxine (T4) and Tri-iodothyronine (T3)) which regulate body metabolism.
• Parafollicular cells (C-cells) – produce calcitonin hormone which regulate level of calcium in the body.

Other cells in thyroid gland include,
• Lymphocytes. These are immune system cells.
• Stromal cells. These are supportive cells.

Hormones are chemical messengers secreted by endocrine glands into the blood stream which are responsible for controlling different processes in the body. Thyroid gland as one of the endocrine glands, secrete hormones responsible for regulating metabolism of the body. Such as regulation of heart rate, body temperature, body weight and blood pressure.

The change in thyroid hormone levels can cause changes to how your cells respond:->
• Hypothyroidism – The thyroid gland produces too few hormones causing the metabolism to slow down. This will cause heart to slow down, feel tired, dry skin and unexplained weight gain.
• Hyperthyroidism – The thyroid gland produces too many hormones causing the metabolism to speed up. This will cause a rapid or irregular heartbeat, trouble sleeping, nervousness, hunger, weight loss, and a feeling of being too warm.

Types of this cancer
• Papillary thyroid cancer. This type of thyroid cancer develop from follicular cells and tend to grow slowly. This type of cancer normally spread to the nearby lymph nodes. Papillary thyroid cancer is one of the three types of differentiated thyroid cancer as appearance of tissues under microscope is similar to that of normal tissues.
• Follicular thyroid cancer. This develop from follicular cells and normally grow slowly. This type rarely spread to the lymph nodes but it can spread to other parts of the body such as lungs. Follicular thyroid cancer and papillary thyroid cancer are the most common differentiated thyroid cancers. If they are detected early, there is high chance of being cured.
• Hurthle cell carcinoma. This type of cancer arise from follicular cells. This type of cancer is more likely to spread to lymph nodes than other follicular thyroid cancers.
• Medullar thyroid cancer. Medullar thyroid cancer develops from the parafollicular cells (C-cells) and can run in families.
• Anaplastic thyroid cancer. This type of cancer may develop from undiagnosed papillary or follicular thyroid cancer and usually grows quickly. This type of cancer is poorly differentiated. This type of cancer is normally difficult to treat successfully.

Risk factors
When it comes to cancer, anything that increases your probability of developing cancer is called a risk factor. Risk factors only influence development of cancer but it does not directly cause cancer. Sometimes people with risk factors do not develop the disease while those with no risk factors do develop the disease. Knowing risk factors will help you live your life making some better healthy choices to reduce the risk. The following factors may increase your risk of developing thyroid cancers.

• Family history. There are some types of thyroid cancer that may run in families. Some people inherit a faulty gene called the RET pro-oncogene, which increases their risk of developing thyroid cancer. This may occur in familial medullary thyroid cancer (FMTC).
• Radiation exposure. The risk of developing thyroid cancer is slightly high to those who had radiation therapy during their childhood especially radiotherapy of head and neck. This group also include those living in environment with high level of radiations. For example in areas where there is nuclear accident.
• Benign thyroid diseases. Some of the thyroid cancers develop as a result of conditions such as thyroid nodules, an enlarged thyroid (goiter) or inflammation of the thyroid.
• A diet low in iodine. Some follicular cancers may develop as a result of lack of enough iodine in the body which is needed for normal thyroid gland function.

Prevention
To prevent something you need first to know what causes it. Since the specific cause of thyroid cancer is still not clear, then there is no proven way to completely prevent development of this cancer but there are ways that may help to lower the risk of developing it although most cases of thyroid cancer have no known risk factors. These include the following,
• Taking diet that contain iodine. Since lack or enough iodine in the body increase the risk of developing thyroid cancer, then taking diet that contain iodine is recommended. Nowadays this is not a serious problem in Tanzania as most people get enough iodine in their diet because it is added to table salt and other foods.
• Since radiation exposure at childhood increase a person`s chance of developing thyroid cancer at some point of their life, the use of radiation to treat less serious diseases is not an option.

Early detection and screening of thyroid cancer
When it comes to cancer, early detection normally provide better treatment outcome. When thyroid cancer is found early, chances for better treatment outcome are very high. For most cancers, early detection has been greatly contributed by the presence of screening processes. Screening is the process of running some tests to someone with no symptoms of a certain disease with the intention of determining presence or absence of that disease. Unfortunately, till now there is no widely recommended screening tests for thyroid cancer. Despite absence of screening tests for this cancer, most thyroid cancers are nowadays found much earlier than in the past, hence they can be treated successfully.

Most early thyroid cancers are found when patients see their doctors because of some symptoms they have noticed such as, neck lumps or nodules. Other cases are detected during routine checkups or during tests for other health problems. Although some people have a higher risk of getting thyroid cancers than others, but it’s important to know that anyone can develop thyroid cancer.

Signs and symptoms
People with thyroid cancer may experience the following signs and symptoms. Sometimes, people with thyroid cancer do not have any of these changes. Or, the cause of those symptom may be another medical condition that is not cancer, hence seeking for medical care upon experiencing any of those symptoms is advised. Signs and symptoms of thyroid cancer include the following;

• Hoarseness of voice that doesn`t get better for weeks.
• Painless lump or swelling in the front of the neck that may grow bigger.
• Sore throat that doesn`t get better.
• Difficulty swallowing or breathing.
• Swollen gland in the neck
• Persisting cough that is not caused by cold.

Diagnosis Medical diagnosis simply means identification of nature of an illness by elimination of the symptoms. Normally people don`t go to hospital knowing they have cancer but during diagnostic procedures is when doctors detect the disease.

Following suspicion of the disease, doctors normally run combination of tests to determine whether there are cancerous cells in the body or not and if there are cancer cells, how far have they spread. Along with thorough medical history and physical examination, doctors normally use combination of the following tests to diagnose cancer.

Laboratory tests. Laboratory tests are important in ruling out other conditions and confirming diagnosis. For cancer diagnosis laboratory tests normally include blood tests, urine tests, tumor markers and other body fluids tests.
Blood tests. Blood tests help to reveal level of different substances in the blood which will help doctors to know if there is anything wrong in the body. From blood tests doctors can see complete blood count which indicates number, size and maturity of blood cells. Also from the blood tests doctors can analyze if kidney and liver are working properly.
Urine tests. Urine tests (urinalysis) involve laboratory examination of urine to check presence of blood, proteins, and other substances such as drugs. For instance, blood in the urine may be an indication of benign condition, infection or other health problem.
Tumor markers. These are biomarkers (proteins) that can be produced by both cancer cells and normal body cells in response to cancer. Tumor markers are released into the blood or urine. Although studies are still conducted to determine role of these markers in diagnosing cancer because sometimes people with benign condition will have elevated level of these proteins. Also not all tumors have their markers and some markers are not specific to one type of tumor. Other body fluids. Despite being rarely used, sometimes body fluids can be tested in the lab during diagnosis of cancer. For instance, the use of cerebral spinal fluid (CSF) and pleural fluid. CSF is used in diagnosis of brain tumors while pleural fluid for lung cancer.

Diagnostic imaging. Diagnostic imagings involve tests that create pictures of inside the body that help the doctor to see if there is tumor or not. There are several imaging tests used in cancer diagnosis depending on the type and location of cancer suspected. These imaging tests include;
Computed tomography (CT) scan. CT scan machine is a donut-shaped scanner that uses x-rays to create series of pictures of body organs from different angles. This machine is linked to a computer where those series of pictures taken will be combined to create a 3D- image of inside the body. During the scanning process patient will lie still on the table which will slide into the scanner. In order to get a clear image, sometimes the doctor will inject the patient with a contrast material before scanning. From the images the doctor will be able to differentiate between healthy and unhealthy tissues.
Magnetic resonance imaging (MRI). MRI is an imaging technique that uses powerful magnet and radio waves to take series of pictures of body organs and create a 3D image in a computer linked to a machine. Just like in CT, during MRI procedure the patient will lie on a table that will slide into a long round chamber. Also during this procedure, the doctor may inject the patient with a contrast material for clear image view.
X-ray. This is an imaging technique that is uses low dose of radiation to create pictures of inside your body. Technician will position the patient and direct the x-ray beam to the intended part of the body.
Ultrasound. Ultrasound is a diagnostic imaging procedure that uses high energy sound waves to produce images of organs inside the body. During the examination, a patient will lie on the table while the technician will slowly move a device called transducer on the skin over the part of the body that is being examined.
PET scan. Positron emission tomography (PET) scan is an imaging test that uses radioactive glucose to create 3-D images of areas inside the body. Radioactive glucose is used for this test because cancer cells tend to absorb more glucose than normal body cells, so the scan will show which areas of the body has more glucose than others. Before the scan, doctor will inject the patient with tracer called radioactive glucose then during imaging the patient will be asked to lie on the table that will be moving back and forth through the scanner.

Bone scan. Bone scan is used to examine bones. When it comes to cancer, bone scan is used for diagnosis of bone cancer or cancer that has metastasized into the bones. Before the test, patient will be injected with small amount of radioactive material that tends to collect more on abnormal parts of the bones. Then pictures that will be taken by a scan will indicate the distribution of those radioactive materials in the bones throughout the body.

Biopsy. Biopsy is a diagnostic procedure that involves removing a tissue sample from the body and examines it under microscope in the laboratory. Examination in the laboratory is normally done by a pathologist who will check if the cells in the tissue are cancerous or not. In most cancer cases, biopsy is considered to be the confirmatory test. Depending on the location and type of cancer, biopsy can be obtained in different ways. Some of them include;
Using needle. By using a thin needle, doctors can draw same tissue or fluid for examination under microscope. This method can be used to draw some fluid (spinal tap), bone marrow (bone marrow aspiration), blood or small amount of tumor from the suspected organ such as liver and breast (fine needle aspiration).
Surgery. Abnormal tissue samples are obtained while the doctor is performing the surgery. Tissues are then sent to the lab for examination during the surgery. If the surgeon removes just a portion of abnormal area, it is called incisional biopsy while when the entire tumor (abnormal site) is removed it is called excisional biopsy.
Using endoscope. Endoscope is a thin, lighted tube with a camera (focusing telescope) at the end. It is used for viewing inside the body through natural openings like mouth and anus. During an examination if the doctor sees any abnormal tissue, then endoscope can also be used to take sample for that tissue. There are different kinds of endoscopy exams depending on the site of the body being examined. Some of the exams include colonoscopy (for rectum and colon), bronchoscopy (for trachea, bronchi and lungs) and esophagogastroduodenoscopy EGD (for esophagus, stomach and duodenum)


In addition to physical examination and medical history, diagnosis of thyroid cancer normally involves the use of ultrasound, blood tests, radioisotope scan, biopsy which is normally used as confirmatory test and other imaging tests.

• Blood test. Blood tests are not used to find thyroid cancer. But they can help show if your thyroid is working normally, which may help the doctor decide what other tests may be needed. Levels of hormones (such as T3 and T4), calcitonin and thyroid-stimulating hormone (TSH) will be checked. If the tests reveal that, the levels of those hormone is not as they are supposed to be, then more tests will be done in order to know the reason. For example; High calcitonin levels in the blood can indicate medullary thyroid cancer.
• Radioisotope scan. If the blood test shows evidence of an overactive thyroid


note: (hyperthyroidism), radioisotope scan may be used. The test can also help to determine if a lump in the neck is a thyroid cancer or not. This test is also used those who have been diagnosed with differentiated (papillary, follicular, or Hurthle cell) thyroid cancer to help show if it has spread. If cancer is medullary thyroid, radioisotope scan will not be suitable because medullary thyroid cancer cells do not absorb iodine.

Treatment of thyroid cancer Following cancer diagnosis, the doctor will break the news and it is normally not very easy to accept that it is cancer. The doctor will be there to help the patient process the news and to help the patient in taking the next steps. After the patient receives and processes the news that he/she has cancer, one of the most important steps that will follow is decision making. The doctor will present to the patient (relatives/parents/guardians) with all the possible treatment options and explain what they mean. Then with the help of the doctor, the patient (relatives/parents/guardian) will have to choose which treatment option is good depending on benefits of such option. Despite all the information given by the doctor, sometimes the patient may still be unsatisfied with what he/she has been told. In such situation, the patient is free and advised to seek a second opinion. Second opinion is the opinion that the patient may seek from another specialist (doctor) regarding his/her health problem and in this case it is cancer. Second opinion may include confirmation of the diagnosis, more clarification on your primary doctor recommendations or even reassurances that all the options have been explored. In addition to standard care treatment options, sometimes there are those new treatments or drugs or combination of treatments that have not been approved yet to be used as standard care treatments for a particular cancer (disease) but have shown some promising results that they may help. These type of treatments are called clinical trials. If there are some clinical trials for your case, the doctor may present to the patient or the patient may ask if there are any clinical trials for the particular cancer case. Over the years, have improved treatments and led to better outcomes to people diagnosed with various diseases including cancer. If you have decided to take part in clinical trial, you can also withdraw at any time

Treatment options

Surgery
Surgery is the treatment option that involves removing tumor and surrounding healthy tissues during operation. For treatment of thyroid cancer, surgery can be done in the following ways depending on extent of the disease.

• Total thyroidectomy. This involves removing the entire thyroid gland including isthmus.
• Partial thyroidectomy. This involves removing only part of the affected lobe or section of the thyroid.


With either type of operation, the surgeon may remove nearby lymph nodes depending on whether there is risk of lymph node involvement. This is called lymphadenectomy. It is also performed as a preventive measure or if the lymph nodes are enlarged due to the cancer spreading.

Side effects

• Excess bleeding
• Risk of wound infection
• Risk of hoarseness of voice. This may be caused by damage of nerves to the larynx during surgery
• Change of mood due to change in hormone level.
• Neck discomfort. Sometimes surgery can result to stiff neck and back.
• Low calcium level that may occur if parathyroid gland is affected.

Without the thyroid gland, the body stops producing thyroid hormone, which is essential to the body’s function. Hormone replacement which is usually given by a daily pill is the best solution. The patient may also have to take vitamin D and calcium supplements if the parathyroid gland function is impaired after surgery.

Hormone replacement therapy
In addition to maintaining body’s normal metabolism by replacing missing thyroid hormone after surgery. Medications that are given for hormone replacement purposes can also help to stop any remaining cancer cells from growing. This can be possible as medications will help to lower TSH levels.

side effects
• Irregular or rapid heartbeats may occur as a result of high level thyroid hormone in the blood due to the overdose of the medication.
• Weakened bones (osteoporosis) may occur as a result of using high dose of thyroid hormone over a long period.

Radioactive iodine treatment
Radioactive iodine (RAI) treatment is a type of internal radiotherapy that is sometimes known as I-131 or radioactive iodine ablation. Since thyroid absorbs almost all iodine that enters a body, hence iodine can find and destroy thyroid cells not removed by surgery and those that have spread beyond the thyroid. It is usually taken in either liquid or pill form. This treatment is given by endocrinologist or nuclear medicine specialist.

Patients who receive I-131 to destroy cancer cells may be hospitalized for some time (2 to 3 days), depending on several factors, including the dose given. Patients are encouraged to drink fluids to help the I-131 pass quickly through the body. Within a few days, most of the radiation is gone.

side effects
• Being radioactive temporary
• Nausea
• Feeling thirsty
• Feeling tired
• Breathless

Radiation therapy
Radiation therapy is the use of high energy x-rays or other radiation particles to destroy cancer cells. For treatment of thyroid cancer, external bean radiation therapy is used. External beam radiation therapy is the type of radiation therapy in which radiations are given from the source (machine) outside the body to destroy cancer cells. A doctor specialized in giving radiation therapy is known as radiation oncologist. External-beam radiation therapy is used to treat thyroid cancer only in certain circumstances, typically when later-stage thyroid cancer has not responded to I-131 therapy. Radiation therapy is usually given after surgery, and treatment is concentrated on a specific area, only affecting cancer cells at that site.

Side Effects

• Pain and difficulty swallowing
• Feeling tired
• Sore throat
• Hoarseness (occasionally)
• Cough
• Mild skin reactions

Chemotherapy
Chemotherapy is the treatment option that involves using drugs to destroy cancer cells or slow its growth. Doctor who is specialized in treating cancer by using drugs is known as medical oncologist. Chemotherapy is sometimes used to treat advanced thyroid cancer that is not responding to radioactive iodine treatment. The drugs are usually given by injection into a vein

• Hair loss
• Nausea and/or vomiting
• Loss of appetite
• Risk of infection due to low white blood cells
• Feeling tired as a result of low red blood cells
• Easily bruised and bleeding due to low blood platelets count.
• Hearing loss
• Mouth sores

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