Thyroid cancer: treatment, age, what survival?

Thyroid cancer has a good prognosis. Nodules are benign in 95% of cases : these are not cancers, they are hyperplasias, adenomas or cysts. Thyroid cancer is most often discovered by the presence of a nodule discovered by chance during an imaging examination (ultrasound of the neck) or a palpation of the neck. According to data from theNational Cancer Institute (Inca), it is estimated about 10,500 the number of new cases of thyroid cancer per year in France. Women represent 2/3 of new cases. What causes thyroid cancer? What are the signs ? How is it diagnosed? When do we operate?

What is thyroid cancer?

Thyroid cancer is cancer that affects the thyroid gland. There are two main families:

► Follicular stem thyroid cancers which are the most frequent (they represent 90 to 95% of thyroid cancers). “Among follicle stem cancers, the most common is papillary cancer thyroid which represents 80% of cases of follicular strain cancers“, says Dr. Livia Lamartina, oncologist specializing in nuclear medicine at Gustave Roussy.

► Medullary thyroid cancers which develop at the expense of the C cells of the thyroid and which are much rarer (they represent about 5% thyroid cancer). “A quarter of medullary thyroid cancers arehereditary originwhich requires family screening“ continues our interlocutor.

What are the symptoms of thyroid cancer?

Thyroid cancer is usually not aggressive and causes few telltale signs. This is why, most of the time, this cancer is discovered fortuitouslyon the occasion of an ultrasound screening for another reason (Doppler ultrasound to check the vessels of the neck in general), during which one can find a thyroid nodule. The main (rare) symptoms are:

► The presence ofa nodule (small ball) at the level of the neck

► Voice modification (hoarsely Or “broken“) or loss of voice, following the presence of the nodule.

► One sore throat which persists (although not very specific to thyroid cancer).

► Sometimes the development ofa goiter.

​​​​​​​What is the average age at diagnosis?

“The average age at diagnosis is around fiftyreplies Dr. Lamartina. The frequency of this cancer increases with age, as does the appearance of thyroid nodules“.

What are the causes or risk factors for thyroid cancer?

A risk factor can promote the development of cancer, but the presence of one or more risk factors does not systematically lead to the appearance of cancer. Conversely, cancer can develop without the person having any risk factors. For thyroid cancer, two main risk factors are identified:

► exposure to radiation, during childhood,observed in particular in children who have undergone external radiotherapy. These children must enter screening programs because they have an increased risk of developing thyroid cancer.“, explains our interlocutor. In adults, exposure to radiation does not represent a risk factor because the thyroid (which is no longer developing like in children) is no longer radiosensitive.

► A family and/or genetic background, with the alteration of RET gene identified as promoting the development of medullary thyroid cancer. “There are several types of alteration of the RET gene and depending on the type of alteration, we can predict the risk (which can range from 0 to 50% risk) and thus guide the type of monitoring. Each time a person is diagnosed with medullary thyroid cancer, all of their relatives can be screened using a genetic test (which is done on a blood sample), which makes it possible to define the risk and the type of monitoring to be implemented“, details Dr. Lamartina.

​​​​​​​What is the survival prognosis for thyroid cancer?

Thyroid cancer is a cancer of good prognosis. Deaths related to thyroid cancers are very rare and concern people refractory to treatment. “In the vast majority of cases, thyroid cancer is curable very well thanks to surgerywith an estimated 5-year survival rate of 98% for both men and women“, reassures the oncologist. The younger the person is at the time of diagnosis, the better the prognosis.

Thyroid cancer presents as a nodule that can be detected during a palpation of the neck or discovered, very often, fortuitously during an imaging examination carried out for another reason (ultrasound to check the vessels of the neck for example).

► The first basis for evaluating a thyroid nodule is cervical or thyroid ultrasound: a non-invasive examination that allows to estimate the size of the nodule and its characteristics (whether it is liquid, solid or mixed). This makes it possible to define the degree of suspicion of a nodule, knowing that most thyroid nodules are considered “not suspicious”.

► Depending on the degree of “suspect”, a cytopuncture of the nodule is carried out (sample of the nodule with a fine needle to analyze it under the microscope) which makes it possible to specify whether the cells are rather reassuring (normal) or suspicious of thyroid cancer (or sometimes between the two, which requires a second check). For small nodules that are not suspicious, there is not even a need to do a cytopuncture.

► To date, to avoid massive overdiagnosis, “screening for thyroid cancer should not be systematic“, wishes to remind our interlocutor. Indeed, the diagnosis of an undetectable tumor on palpation and which would not have evolved into the disease, causes heavy treatments (ablation of the thyroid with levothyroxine taken for life, etc.)with a risk of complicationssignificantly greater than the risk that the nodule will progress to disease or death

What are the treatments for thyroid cancer?

► For very small cancers (less than 1 cm): The surgery is not systematic. “If the nodule is less than 1 centimeter, it is not necessarily necessary to remove it. The patient is then offered active monitoring with regular ultrasounds. If the nodule does not evolve, it is considered that there is less risk of “simply” monitoring it rigorously rather than operating. Of course, the patient must agree with this approach and commit to follow-up“, details Dr. Lamartina.

► When the nodule is more than 1 centimeter: “it is better to operate. Surgery is the reference treatment. The removal of the thyroid can be partial and concern only half of the thyroid affected by the cancer (we speak of thyroid lobectomy) or total if the tumor is more than 2 cm (we speak of total thyroidectomy). “When you do a lobectomy, there is about a 50% chance of still having thyroid hormone secretion. On the other hand, in the event of total ablation of the thyroid, the patient needs to take replacement therapy daily for life to compensate for the absence of thyroid hormone secretions“, continues the specialist. Depending on the lymph node involvement, the lymph nodes around the thyroid must sometimes be removed“, explains the oncologist. Depending on the characteristics of the tumor and the risk, it will sometimes be necessary to administer complementary treatment with radioactive iodine to destroy thyroid remnants. This treatment is reserved for patients at intermediate to high risk of relapse. It is therefore not a systematic treatment. Depending on the risk, the treatment is adapted. “Patients with thyroid cancer low risk of relapse should no longer receive radioactive iodine treatment after thyroid surgery, has shown a study conducted by physician-researchers from Gustave Roussy and the French national network TUTHYREF and published in the New England Journal of Medicine from March 10, 2022“, reports our interlocutor.

We speak of metastases when cancerous cells can detach themselves from the initial tumor and borrow the lymphatic or blood vessels to invade other parts of the body. Follicular strain thyroid cancers give rarely metastases (10% of cases). For medullary cancers, the risk of metastasis is a little more frequent (around 30% of cases). Thyroid cancer can metastasize to:

• The lymph nodes located in the neck. We then speak of lymph node metastases or lymph node invasion.
• other organsnotably lungs or bones. We are talking about distant metastases.

“It exists biomarkers relatively reliable that facilitate follow-up in the case of thyroid cancer. For medullary thyroid cancers, we can measure calcitonin. A normal calcitonin level indicates that there are no remaining tumors. An elevated calcitonin level requires imaging tests to find the cause. For follicular strain cancers, the dosage of thyroglobulin makes it possible to check that there is no involvement of the lymph nodes or other organs. Also, when we administer a treatment based on radioactive iodine, we take the opportunity to a scintigraphy. This test helps determine if the cancer has spread outside of the thyroid.”concludes Dr. Lamartina.

Thanks to Dr Livia Lamartina, oncologist specializing in nuclear medicine at Gustave Roussy.

Sources:

– Thyroid cancers: the key points, National Cancer Institute /

– New England Journal of Medicine: No benefit of radioactive iodine in low-risk thyroid cancer, Gustave Roussy, March 22, 2022