Erin Thyroid cancer accounts for 1.2% of all malignant cancers and 0.2% of cancer deaths in the United States.1 The female to male ratio of thyroid cancer cases is greater than 2:1. Approximately 17,200 new cases were diagnosed in 1998, with 12,500 of them occurring in females. Thyroid exposure to radiation, especially before puberty, increases the risk of developing thyroid cancer. The risk of developing thyroid cancer increases with age.
Etiology:
Spencer Although there are not very many outside factors associated with thyroid cancer, there are still a few possible things that make a person more likely to develop a tumor.2 - Gender and Age - Radiation - Low Iodine in Diet - Family History
Signs & Symptoms:
Pablo Signs and Symptoms include
A lump of nodule in the neck
Enlargement of the neck
Hoarseness and voice changes
Dysphasia
Aphasia3
Diagnostic Procedures:
Megan Unfortunately there is no physical finding or lab test that can be done to detect thyroid cancer; unless it’s medullary thyroid cancer, then a serum calcitonin level can be checked.4 Since thyroid nodules have been linked to intraglandular calcification, x-rays can help distinguish the calcification.4 Radionuclide imaging, ultrasonography, and fine needle aspiration biopsies are all other techniques used to establish an accurate diagnosis of thyroid cancer. Iodine 131, Iodine 125, Iodine 123 and Technetium 99m are all used in nuclear medicine studies to establish function, evaluate for high and low risk staging, and detection of metastases.4 With ultrasound, a high resolution high frequency transducer is used to determine the size of nodules and whether they are cystic, adenomas, or cancer.4 For the best results, the fine needle aspiration , when used on 1-3 cm nodules, can determine benign and malignant differentiation with 95% accuracy.4
Histology:
Adam The thyroid is made up of follicles, which are hollow sacs that absorb iodine from the blood for storage. Surrounding these follicles are epithelial cells (follicular cells), which use the stored iodine in the follicles to produce the primary thyroid hormones. Between the follicles and the epithelial cells are the parafollicular cells, which are responsible for secreting calcitonin.5 Different cancers can arise in the thyroid depending on where they originate. For example, differentiated thyroid cancer comes from the follicular cells, and medullary cancer arises from the parafollicular cells.6
Lymph node drainage:
Megan7
Metastatic spread:
Kevin T
Metastasis to level VI (pretracheal, paratracheal, and prelaryngeal/Delphian lymph nodes)8
Metastasis to unilateral, bilateral, or contralateral cervical (Levels I, II, III, IV, or V) or retropharyngeal or superior mediastinal lymph nodes (Level VII)
Grading:
Erin A very descriptive system is used for staging thyroid cancer baesd on histologic type and age of the patient, however there is no specific grading system used.9
Staging:
Spencer American Joint Committee on Cancer Staging System for Thyroid Cancer.10 TNM
Primary Tumor (T) TX – Primary tumor cannot be assessed. T0 – There is no evidence of the primary tumor. T1 – Tumor is 2cm or less in the greatest dimension. T1a – Tumor is 1cm or less. T1b – Tumor is more than 1cm but no greater than 2cm, and limited to the thyroid. T2 – Tumor is more than 2cm but no more than 4cm in the greatest dimension, and also limited to the thyroid. T3 – Tumor is more than 4cm in the greatest dimension but also limited to the thyroid. T4a – Moderately advanced disease. Any tumor existing beyond the thyroid to invade other structures. T4b – Very advanced disease. Any kind of tumor that invades vertebral bodies or vessels.
Regional Lymph Nodes (N) NX – Regional lymph nodes that cannot be assessed. N0 – No regional lymph node spread. N1 – Regional lymph node spread. N1a – Metastasis to level VI (pretracheal, paratracheal, and prelaryngeal lymph nodes) N1b – Metastasis to unilateral, bilateral, or contralateral lymph nodes.
Pablo Radiation side effects The side effects for radiotherapy can range from mild to severe depending on the dose received. These include the following.
Development of hypothyroidism
Enlarged thymus, and tonsils
Craniopharyngioma (more common in children than adults)
Growth hormone deficiency
Premature sexual development¹
If the patient receives radioiodine therapy the following may occur as a result of treatment.
Nausea and headaches
Vomiting
Altered sense of smell
Parotid swelling
Because of long survival rates for thyroid cancer, more secondary malignancies are being observed associated with the treatment of thyroid tumors.11
Prognosis:
Becky
Factors that affect prognosis include gender, age, tumor size, histologic subtype, capsular invasion and distant metastases.
For tumors that have extended outside the thyroid tend to have a worse prognosis.
Treatments:
Adam The recommended treatments for thyroid cancers vary depending on the type of cancer. For differentiated thyroid cancer, the initial recommendation is surgery, with either a near-total or total thyroidectomy. Then, as an adjuvant therapy, the use of Iodine-131 and thyroid hormone suppression together resulted in a 2.6% recurrence rate and a 0% death rate.6 If the tumor does not take up the Iodine-131, external beam therapy can be used instead. For medullary thyroid cancer, it's also recommended that the tumor be removed surgically. This is especially important in medullary thyroid cancer cases, as they tend to metastasize quickly. Similar to differentiated thyroid cancer, Iodine-131 should be used inconjuction.6 Finally, anaplastic thyroid cancer should be treated with a combination of surgery, irradiation, and chemotherapy. When treating thyroid cancers with external radiation, high doses are required and care should be taken to minimize radiation injuries. For gross disease, radiation treatments of up to 70 Gy are necessary.6
Chao C, Perez C, Brady L. Radiation Oncology Management Decisions. 3rd ed. PA: Lippincott Williams and Wilkins; 2011: 322.
Washington CM, Leaver D. Principles and Practice of Radiation Therapy. St. Louis, MO: Mosby Inc; 2010:648.
Chao, K, Perez, C, Brady, L. Radiation Oncology Management Decisions. 3rd ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2002.
Cox JD, Ang KK. Radiation Oncology: Rationale, Technique, Results. 9th Ed. Philadelphia, PA. 2010.
Vonkadich AC. Overview of radiobiology. In: Washington CM, Leaver D, eds. Principles and Practice of Radiation Therapy. 3rd ed. St. Louis, MO: Mosby-Elsevier; 2010:57-83.
Thyroid cancer accounts for 1.2% of all malignant cancers and 0.2% of cancer deaths in the United States.1 The female to male ratio of thyroid cancer cases is greater than 2:1. Approximately 17,200 new cases were diagnosed in 1998, with 12,500 of them occurring in females. Thyroid exposure to radiation, especially before puberty, increases the risk of developing thyroid cancer. The risk of developing thyroid cancer increases with age.
Although there are not very many outside factors associated with thyroid cancer, there are still a few possible things that make a person more likely to develop a tumor.2
- Gender and Age
- Radiation
- Low Iodine in Diet
- Family History
Signs and Symptoms include
Unfortunately there is no physical finding or lab test that can be done to detect thyroid cancer; unless it’s medullary thyroid cancer, then a serum calcitonin level can be checked.4 Since thyroid nodules have been linked to intraglandular calcification, x-rays can help distinguish the calcification.4 Radionuclide imaging, ultrasonography, and fine needle aspiration biopsies are all other techniques used to establish an accurate diagnosis of thyroid cancer. Iodine 131, Iodine 125, Iodine 123 and Technetium 99m are all used in nuclear medicine studies to establish function, evaluate for high and low risk staging, and detection of metastases.4 With ultrasound, a high resolution high frequency transducer is used to determine the size of nodules and whether they are cystic, adenomas, or cancer.4 For the best results, the fine needle aspiration , when used on 1-3 cm nodules, can determine benign and malignant differentiation with 95% accuracy.4
The thyroid is made up of follicles, which are hollow sacs that absorb iodine from the blood for storage. Surrounding these follicles are epithelial cells (follicular cells), which use the stored iodine in the follicles to produce the primary thyroid hormones. Between the follicles and the epithelial cells are the parafollicular cells, which are responsible for secreting calcitonin.5 Different cancers can arise in the thyroid depending on where they originate. For example, differentiated thyroid cancer comes from the follicular cells, and medullary cancer arises from the parafollicular cells.6
A very descriptive system is used for staging thyroid cancer baesd on histologic type and age of the patient, however there is no specific grading system used.9
American Joint Committee on Cancer Staging System for Thyroid Cancer.10
TNM
Primary Tumor (T)
TX – Primary tumor cannot be assessed.
T0 – There is no evidence of the primary tumor.
T1 – Tumor is 2cm or less in the greatest dimension.
T1a – Tumor is 1cm or less.
T1b – Tumor is more than 1cm but no greater than 2cm, and limited to the thyroid.
T2 – Tumor is more than 2cm but no more than 4cm in the greatest dimension, and also limited to the thyroid.
T3 – Tumor is more than 4cm in the greatest dimension but also limited to the thyroid.
T4a – Moderately advanced disease. Any tumor existing beyond the thyroid to invade other structures.
T4b – Very advanced disease. Any kind of tumor that invades vertebral bodies or vessels.
Regional Lymph Nodes (N)
NX – Regional lymph nodes that cannot be assessed.
N0 – No regional lymph node spread.
N1 – Regional lymph node spread.
N1a – Metastasis to level VI (pretracheal, paratracheal, and prelaryngeal lymph nodes)
N1b – Metastasis to unilateral, bilateral, or contralateral lymph nodes.
Distant Metastasis (M)
M0 – No distant metastasis present.
M1 – Distant metastasis.
Radiation side effects
The side effects for radiotherapy can range from mild to severe depending on the dose received. These include the following.
- Development of hypothyroidism
- Enlarged thymus, and tonsils
- Craniopharyngioma (more common in children than adults)
- Growth hormone deficiency
- Premature sexual development¹
If the patient receives radioiodine therapy the following may occur as a result of treatment.- Nausea and headaches
- Vomiting
- Altered sense of smell
- Parotid swelling
Because of long survival rates for thyroid cancer, more secondary malignancies are being observed associated with the treatment of thyroid tumors.11Factors that affect prognosis include gender, age, tumor size, histologic subtype, capsular invasion and distant metastases.
For tumors that have extended outside the thyroid tend to have a worse prognosis.
The recommended treatments for thyroid cancers vary depending on the type of cancer. For differentiated thyroid cancer, the initial recommendation is surgery, with either a near-total or total thyroidectomy. Then, as an adjuvant therapy, the use of Iodine-131 and thyroid hormone suppression together resulted in a 2.6% recurrence rate and a 0% death rate.6 If the tumor does not take up the Iodine-131, external beam therapy can be used instead. For medullary thyroid cancer, it's also recommended that the tumor be removed surgically. This is especially important in medullary thyroid cancer cases, as they tend to metastasize quickly. Similar to differentiated thyroid cancer, Iodine-131 should be used inconjuction.6 Finally, anaplastic thyroid cancer should be treated with a combination of surgery, irradiation, and chemotherapy.
When treating thyroid cancers with external radiation, high doses are required and care should be taken to minimize radiation injuries. For gross disease, radiation treatments of up to 70 Gy are necessary.6
Tissue dose associated with 5% injury rate within 5 years.
--Ear: 3000cGy—Acute serous otitis
--Optic chiasma: 4500cGy—blindness
--Eye lens: 1000cGy—cataracts
--Optic nerve: 5000cGy—blindness
--Salivary gland: 5000cGy—Xerostomia
--Spinal cord: 4500cGy--Myelitis
--Oral cavity: 6000cGy--ulceration.12