Undifferentiated thyroid carcinoma (ATC) is rare, accounting for about 1% to 2% of all thyroid cancers, and can be subdivided into several subtypes based on cell morphology. In some ATC tumors, papillary or follicular carcinoma may be found, a manifestation of increased malignancy based on differentiated thyroid cancer.
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Symptoms
ATC has a rapidly progressive course, often with a large, fixed, rapidly growing mass at the time of detection, and with significant clinical manifestations associated with compression or infiltration.
When the tumor compresses the trachea, shortness of breath, dyspnea, hemoptysis, and a feeling of suffocation in the chest may occur; when it compresses the esophagus, discomfort and choking may occur in the less severe cases, and in the more severe cases, the patient may not be able to eat. In the long term, patients can suffer from malnutrition and weight loss.
When the tumor invades the recurrent laryngeal nerve, symptoms such as choking on water and hoarseness may occur; when the tumor invades the esophagus, there may be difficulty swallowing and vomiting blood due to tumor bleeding; when the tumor invades the larynx and trachea, it may also cause difficulty breathing and hemoptysis.
Staging
ATC is the most malignant of all types of thyroid cancer and is diagnosed at an advanced stage (stage IV), which can be subdivided into stages ⅣA to ⅣC.
| Staging | Meaning |
|
Phase IVA |
No lymph node metastases or distant metastases, primary focus confined to the thyroid |
|
Stage IVB |
No lymph node metastasis and distant metastasis with significant primary invasion to extra-thyroidal tissue; or no distant metastasis, with lymph node metastasis and a primary focus confined to the thyroid gland |
| Stage IVC | Distant metastases, regardless of the extent of the primary focus or the presence of lymph node metastases |
Treatment
- Overall, the treatment of ATC is tricky. Many patients already have distant metastases at the time of diagnosis, and effective treatment is limited. If resection is possible, then surgery remains the treatment option of choice. Postoperative supplementation with external radiation therapy (radiotherapy) may prolong survival. However, if the tumor has already involved vital organs such as the trachea and esophagus, or if distant metastases are already present, extensive surgery will not help to extend survival time instead.
- For patients who have lost the chance of surgery, radiotherapy is the first approach that doctors consider.
- Undifferentiated carcinoma takes up little iodine and is not sensitive to chemotherapy, so radioactive iodine (RAI) therapy and chemotherapy are generally not used.
- At present, targeted drugs for undifferentiated cancers are still in clinical research stage and have not entered clinical use.
Co-written by Dr. Kai Qian, Cancer Hospital of Fudan University, Dr. Weibo Xu