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Thyroid Cancer » Types of thyroid cancer
Papillary thyroid cancers
- Papillary thyroid cancers (PTC) represent 75-80% of all thyroid cancers.
- PTC is more common in the age range of 20-50, in women and in the regions rich in iodine.
- Papillary cancers tend to spread through the lymphatic system. Therefore, they may cause lymph node metastases in the neck.
- It is seen more frequently in those with the history of radiation exposure of the neck to radiation.
- It can be diagnosed by needle biopsy.
- Overall survival is close to 100% under the age of 45 years and is above 90% over the age of 45 years.
- The rate of lymph node metastasis is high in PTC. Lymph node metastasis is identified in 15-30% of patients by US and/or clinical examination.
- In 30-80% of patients with PTC, the disease is multifocal, ie there are multiple tumors. Although cancer is detected only in one nodule by biopsy, multiple tumors with small foci can be seen in the postoperative pathologic examination.
- Some subgroups of papillary cancer (tall cell, sclerosing) have poor prognosis. The rate of lymph node metastasis is higher.
- Papillary cancers are very sensitive to radioactive iodine therapy. If the tumor diameter is larger than 1 cm, radioactive iodine therapy is administered. The goal of radioactive iodine therapy is the elimination of lymph node metastases that are not visualized or detected by ultrasonography. Some patients may have distant metastases (lung metastasis) that can not be determined before the surgery. Radioactive iodine therapy is also used to treat possible lung metastases.
- Distant metastases are usually seen in advanced, ignored large tumors and in tumors of subgroups with poor prognosis.
- As the tumor diameter increases, the rate of lymph node metastasis increases, radioactive iodine therapy is administered in cases of papillary carcinomas with a tumor larger than 1 cm.
- During the follow up of patients, serum thyroglobulin (Tg) is measured, it is a very sensitive test. Elevated levels of Tg in the postoperative period suggests the probability of metastasis and so the patient is examined.
Follicular thyroid cancers
- Follicular thyroid cancer accounts for 10% of all thyroid cancers
- It is a type that tends to spread through bloodstream.
- The rates of lymph node metastases are lower.
- It is not sensitive to radioactive iodine therapy as much as papillary cancer.
- It cannot be diagnosed by needle biopsy.
- There is 20-40% probability to diagnose follicular cancer in needle biopsy as a result of follicular neoplasm.
Medullary thyroid cancers (MTC)
- MTCs accounts for 5-10% of all thyroid cancers.
- 25% of the MTC are inherited, i.e genetically transmitted. These are diagnosed at a very young age.
- Tumor cells synthesize calcitonin. They may also synthesize somatostatin serotonin besides calcitonin.
- The measurement of serum calcitonin is very valuable in the diagnosis and follow-up.
- %80 of cases can be diagnosed by needle biopsy.
- In MTC, lymphatic metastases most frequently occur in the central area of the neck. However, lymph metastasis can also be seen in other parts of the neck.
- Lymph node metastasis is detected in 50-60% of patients.
- Spread through the bloodstream is mostly detected in the lungs, liver, bone, brain and soft tissues.
- Although survival rate depends on the stage of the disease, 10-year survival is reported to be 75-85%.
- In cases of familial medullary cancers, genetic studies are performed in the family and the thyroids of family members, who are at risk without developed cancer, are surgically removed.
Poorly differentiated thyroid cancers
- Majority of the patients have goitre for many years, and despite the recent history of growth in these nodules, cases of sudden and rapid growth are rare.
- When diagnosed, local recurrence and lymph node metastasis is detected in 60% of patients and distant metastases is detected in 50% of patient.
- 90% of poorly differentiated carcinomas can be diagnosed before the operation with FNAB.
- Radioactive iodine therapy is recommended for all poorly differentiated tumors with iodine uptake after the surgical intervention.
- Patients whose tumor could not be totally removed are recommended to have radiotherapy before radioacive iodine therapy. Chemotherapy is one the treatment options in patients for whom surgical intervention is not considered.
- It is reported that 5-year survival is 50%, 10-year survival is 30%.
- Anaplastic cancers account for 2% of thyroid carcinomas.
- Majority of the patients have the history of rapidly growing mass in the neck. In a short time, compression findings develop.
- It can be diagnosed with FNAB in the ratio of 90%.
- The teory of anaplastic transformation of present papillary thyroid carcinoma is accepted. Mean survival is 12 months.
- Mean survival is 12 months.
- It is known that surgical treatments in anaplastic thyroid carcinomas do not affect the survival rate.
- If respiratory distress arises, tracheostomy (opening a hole) is carried out.