Why do I need iodine 131 treatment after thyroid cancer

Postoperative nail clearing treatment reduces relapse rate

May 25 to 31, 2015 is the seventh "International Thyroid Knowledge Awareness Week". During the promotion week, CCTV Health launched a daily interview of "Medicine Review". From the perspective of experts from Peking Union Medical College Hospital, from the clinical manifestations of thyroid diseases to pathological common sense and case analysis, it will take you to a comprehensive understanding of thyroid diseases. Dr. Lin Yansong, chief physician of the Department of Nuclear Medicine, Peking Union Medical College Hospital, has been invited in this issue of Medical Report.

Postoperative clear nail treatment, as the name implies, is a treatment for a few thyroid tissues that cannot be removed. Why remove normal thyroid tissue? Because it leaves something that may grow again. What kind of organization is easy to grow again, or is it recurring?

In the first case, if there is a distant metastasis, in order to follow up the 131 iodine clearing treatment, a nail clearing treatment must be done, and the thyroid is destroyed.

In the second case, some patients found that the lesion was larger than 1 cm. after surgery, and accompanied by lymph node metastasis, and some people with extrathyroidal invasion, such as invasion of the thyroid capsule, accumulated to the surrounding adipose tissue or fibrous nodular tissue, At this time, thyroid cancer is relatively heavy, and such patients have a high probability of recurrence. However, it is impossible to remove the thyroid tissue completely by surgery or by any experienced surgeon, because there is fear of damage to the parathyroid nerve tissue, so there will be residual thyroid, and these residuals are part of the postoperative treatment , As an important means to reduce the recurrence rate.

If you add nail-clearing treatment after surgery, you can clean up the thyroid tissue and reduce the recurrence rate. First of all, some lesions were cleared during the treatment of thyroidectomy, and secondly, as patients with differentiated thyroid cancer, if the tumor marker-thyroglobulin is high, it can be determined that they are metastatic. The benefit of Qingjia treatment is that, no matter which cycle of thyroid cancer patients, if the treatment is completed, there is no thyroid-producing tissue in the body, which is conducive to long-term follow-up and centralized follow-up.

The completion of a nail sterilization treatment may take 1 to 2 times, but the benefits it brings are lifelong. Thyroglobulin is very sensitive and is a tumor marker for thyroid cancer. Without thyroid, there is no globulin, or globulin is at an undetectable level. Once the globulin is high, the patient has a relapse. After the completion of Qingjia treatment, if iodine is used to show the whole body, you can see that there is no thyroid on the neck. If there are suspicious iodine lesions in the normal gastrointestinal tract, urinary system, etc., they are metastatic lesions.

Radioactive iodine 131 is an important treatment for thyroid cancer after surgery

Differentiated thyroid cancer accounts for about 90% of thyroid cancer, accounting for the vast majority. Why is it called differentiated thyroid cancer? Because it is similar to the original thyroid follicles, they both secrete thyroid hormones and retain iodine uptake. Thyroid tissues rely on iodine and tyrosine to produce thyroid hormones. Thyroid cancer tissues, especially differentiated types, include lactic acid cancer (sound) and follicular cancer. It can take up iodine, and we can use iodine to perform thyroid cancer tissue analysis. For planting and treatment, the iodine referred to here is radioactive iodine 131.

Which thyroid cancer patients can be treated with iodine 131?

　Differentiated thyroid cancer can be treated with iodine 131, but when thyroid tissue and thyroid cancer tissue coexist, iodine cannot directly hit the thyroid cancer tissue. Because of the strong iodine uptake of normal thyroid tissues and weak iodine uptake of cancer tissues, iodine 131 treatment is often an adjuvant treatment after surgery, that is, when normal thyroid tissues are removed almost at this time, thyroid cancer tissues can behave like normal thyroid tissues. Go to ingest iodine 131 to enter the body to achieve the purpose of treatment. This kind of postoperative adjuvant treatment can be used for locally hatched lesions or distant metastases, but if there is thyroid tissue regeneration, iodine 131 will not achieve the intended purpose of hitting the tumor.

How to monitor for recurrence and metastasis after thyroid cancer surgery?

Thyroglobulin is an important marker for postoperative thyroid cancer and thyroid therapy. Monitoring for recurrence and metastasis is usually done by monitoring serum, paying close attention to thyroglobulin and thyroid hormone levels.

　　In addition, ultrasound is a very important imaging method for detecting tumor recurrence and metastasis. It is non-invasive, safe, and convenient. For example, cervical lymph node metastasis cannot be reflected by globulin, but it can be sensitively reflected by cervical ultrasound.

　　For some serious patients, in addition to serum, blood, ultrasound, and detection methods, you can also use iodine 131 whole body imaging to observe where the ingested iodine goes to. If you go to another place when there is no thyroid, it is metastasis. Suspicious signs.

　　There are some lesions that need to be prevented. These lesions do not take iodine and have poor differentiation. How to track them? At this time, relatively advanced positron emission computed tomography in nuclear medicine can be used to detect the glucose metabolism of the lesion, and it can also be used to detect the recurrence of the lesion. Sometimes the presence of the lesion is also detected by a tumor-positive imaging agent. Also imaging, such as CT, magnetic resonance, and spectral imaging, can help detect thyroid cancer metastases and suspicious lesions. These are important auxiliary methods to detect tumor recurrence after surgery.

Genetic testing for individualized and precise treatment of thyroid cancer

Genetic testing is an important component of molecular feature-driven targeted therapy. Precision medicine is driven by molecular features. Thyroid cancer is related to it. When there is a mutation in the BRAF gene , this mutation often occurs in patients with nipple disorders . The mutation rate can reach 40% to 70%, or even 80%. Some RAS gene mutations, such as NRAS , also have ret gene rearrangements detected . Is commonly used in clinical BRAF gene mutation, the RAS gene rearrangement, as well as EGF and the like, this is the direction of our trial and error.

　Recently , patients with mutations in the BRAF gene have a significantly higher local recurrence rate, a higher lymph node metastasis rate, and a higher risk of death. This is a mainstream internationally. A recent study showed that if there is a mutation in the BRAF gene, the risk of death for such patients is about 2.66 times that without the mutation. In addition, the NRAS gene is mutated, and follicles may be easily transferred. After the BRAF gene mutation, it does not heal well. The results show that in patients with BRAF gene mutations, the iodine uptake capacity of distant metastases is significantly reduced, which may be due to the BRAF gene mutations that impede lymph nodes, resulting in poor iodine uptake capacity. The significance of this study is that for patients with distant metastases, a genetic test can be used to find out whether the gene is mutated. If it is mutated, iodine 131 does not work in such patients. Once this happens, you can pre-treat with differentiation-inducing drugs to gain time for subsequent treatments, or change the treatment method as soon as possible, or add auxiliary drugs to change the intake.

　Genetic testing can also predict some recurrences and metastases. BRAF gene mutation, after recurrence, cervical lymph node metastasis rate is also high, and the ability to relapse is also strong, so people who have BRAF gene mutation, although there is no distant metastasis, also need to actively perform nail cleaning. Follow-up intensive visits after treatment of Qingjia. Genetic testing guides a series of processes, guides postoperative adjuvant treatment, and can guide the scope of surgery, which is also a direction for individualized and precise treatment of patients.