Thyroid cancers

Risk factors

Thyroid cancer is promoted by accidental exposure to ionizing radiation as well as by genetic factors.

Symptoms

Thyroid cancer often presents as an asymptomatic thyroid nodule, discovered on clinical examination or incidentally on imaging for another condition. More rarely, the appearance of a cervical lymph node, voice changes, or difficulty swallowing may reveal the diagnosis.

Diagnosis and examinations

The diagnosis of thyroid cancer is made using imaging techniques and fine needle aspiration biopsy. Ultrasound of the thyroid gland provides important information about "nodules," which are small tumors that develop in the thyroid but may not be cancer. Ultrasound is thus coupled to puncture of the nodule with a fine needle and microscopic analysis of the cells collected by the puncture. These different examinations must be carried out with great care in order to guarantee their reliability.

The genetic abnormalities involved in the development of thyroid cancer have been almost completely identified through the Cancer Genome Atlas study in 2014. The emergence of molecular biology techniques (e.g. NGS) currently makes it possible to identify these abnormalities on the puncture material of the thyroid nodule and thus refine its diagnosis. In the future, this will make it possible to avoid unnecessary or too extensive surgery.

In some cases, the assessment is completed by a scintigraphy. Scintigraphy consists in intravenously injecting a very small quantity of radioactive product taken up by the thyroid. An instrument, placed near the neck, detects the radiation emitted by the product. Scintigraphy can be useful to better define the function of the nodule(s).

The information provided by these different examinations guides the choice of treatment.

Treatments

The process leading to the diagnosis of thyroid cancer is subtle and the decision to proceed with surgery is made after careful consideration by all the experts involved: endocrinologists, radiologists, nuclear medicine specialists, pathologists, and surgeons. This multidisciplinary approach makes it possible to identify the most appropriate attitude for each of the cases discussed.

The effectiveness of the treatment depends first of all on an efficient surgical approach. Thyroid surgery, which consists of the partial or complete removal of the gland (thyroidectomy), is challenging due to the proximity of the vocal cords and the parathyroid glands. The parathyroids are small glands, very close to the thyroid, involved in the regulation of calcium and phosphorus in the blood. The surgeon's dexterity makes it possible to control the potential risks of the surgical act.

The administration of radioactive iodine often completes the procedure. Iodine is essential for the synthesis of thyroid hormones and radioactive iodine is able to destroy the few thyroid cells that have been missed by surgery.

Complementary treatment with radioactive iodine requires radiation protection measures to preserve the environment and the people around the patient. It requires a shielded isolation room in which the patient is hospitalized for two to three days.

Surgery and radioactive iodine generally lead to the cure of the cancer. Follow-up, which is essential because of the risk of recurrence, is easy and is based on a very reliable test, namely the measurement of thyroglobulin blood level. Thyroglobulin is the storage protein for thyroid hormones. It is specifically produced by the cells of the thyroid gland. Detectable thyroglobulin indicates the persistence of thyroid cells, whether cancerous or not, while the absence of thyroglobulin and residual thyroid tissue on imaging are considered signs of healing.

After removal of the thyroid, it is necessary to start thyroid hormone replacement therapy.

Combined treatment with surgery and radioactive iodine cures thyroid cancer in 95% of cases. However, the risk of recurrence requires follow-up.

Indeed, the risk of recurrence, mainly within 5 to 10 years, is not zero, so regular follow-up is necessary. It is based on a very reliable test, namely the measurement of thyroglobulin blood level. Thyroglobulin is the storage protein for thyroid hormones. It is specifically produced by the cells of the thyroid gland. Detectable thyroglobulin indicates the persistence of thyroid cells, whether cancerous or not, while the absence of thyroglobulin and residual thyroid tissue on imaging are considered signs of healing.

After removal of the thyroid, it is necessary to start thyroid hormone replacement therapy.

If the disease is more advanced (presence of metastases in other organs), inoperable, and resistant to radioactive iodine, targeted therapy drugs (kinase inhibitors) may be effective. Given their significant adverse effects, they are used on a case-by-case basis after discussion in a multidisciplinary meeting. Participation in clinical trials to evaluate new drugs is also proposed.

Active surveillance of thyroid cancers

In recent years, active surveillance of low-risk thyroid carcinomas has been proposed as an equally effective alternative to immediate surgical intervention. Any adult may benefit from this surveillance if the carcinoma is found to have clinical, ultrasonographic, cytologic, and molecular features indicating a low risk of progression to neighboring organs or distantly. Active surveillance involves regular ultrasound monitoring of the thyroid.

Research / Innovation

The difficulties encountered in the diagnostic and therapeutic approach to thyroid cancer have led the European scientific community to formulate recommendations. The experts of the multidisciplinary group dedicated to thyroid cancer have taken an active part in the elaboration of these consensus texts.

They are also conducting research on the factors that influence the evolution of thyroid cancer. The identification of these markers would allow the therapeutic approach to be further refined. Participation in these studies allows us to offer patients at the King Albert II Institute an approach that is in line with the most recent advances, particularly for the small group of patients with aggressive disease that is refractory to the usual treatment, i.e. surgery and radioactive iodine.

Diagnosis

Like differentiated thyroid carcinoma, medullary carcinoma presents as a thyroid nodule, but its diagnosis is based on the determination of calcitonin in the blood rather than on the puncture of the thyroid nodule. Metastases in lymph nodes or other organs are common. High calcitonin secretion may be responsible for diarrhea and hot flashes.

Treatment

Treatment consists of surgical resection of the thyroid gland and, often, the neck lymph nodes. Unlike differentiated thyroid cancer, medullary carcinoma is not sensitive to radioactive iodine. After surgery, the patient is followed up regularly with measurements of calcitonin in the blood. The persistence of high levels of calcitonin is a sign of persistent cancerous disease, which makes it necessary to search for the residual tumor by ultrasound, PET scan, and/or CT scan and then resect it.

If the disease is more advanced (presence of metastases in other organs) or inoperable, targeted therapy drugs (kinase inhibitors) may be effective. Given their significant adverse effects, they are used on a case-by-case basis after discussion in a multidisciplinary meeting. Participation in clinical trials to evaluate new drugs is also proposed.

Preventive thyroid resection should generally be proposed to affected family members of a patient with hereditary medullary carcinoma, after thorough genetic investigation and at an age to be determined with the physician.