Most people who have been treated for thyroid cancer have a good prognosis and do very well. However, it is important to be aware that thyroid cancer can recur even 10 to 20 years after initial treatment. Thyroid cancer survivors may be affected by several health problems, but their biggest concern is usually the possibility of another type of cancer. Cancer that returns after treatment is called a recurrence, while new, unrelated cancer is referred to as a second cancer.
Recurrent thyroid cancer usually occurs in the neck area, such as the lymph nodes, and is called regional recurrence. In some cases, the cancer may spread to other areas of the body, such as the bones and lungs, which is known as distant metastases. Fortunately, recurrent thyroid cancer still has a good prognosis and is usually treatable. Thyroid-stimulating hormone (TSH) levels are also monitored closely because suppressed TSH is thought to make differentiated thyroid cancer less likely to recur.
In addition, regular blood tests or thyroid scans may be recommended to check for signs that the cancer has returned. The BRAF mutation can be used to predict clinical recurrence in low-risk patients with conventional papillary thyroid carcinoma. It is important to note that some types of thyroid cancer, such as anaplastic thyroid cancers, are very aggressive and can lead to death within 6 months. Overall, only a few patients with thyroid cancer have cancer recurrence within 8 years of initial treatment.
If thyroglobulin levels are low even in the presence of high TSH stimulation, this indicates that there is no recurrence in papillary and follicular thyroid cancers (differentiated thyroid cancers). Nuclear imaging scans that use a radioactive form of iodine and a special camera may also be used to detect thyroid cancer cells. The incidence rate of thyroid cancer has increased due to improved technology that can detect small tumors. Despite this increase in newly diagnosed cases, mortality rates have remained relatively stable.
The increasing incidence of thyroid cancer in the United States is mainly due to increased detection of smaller papillary cancers with tumor size ≤ 2 cm.