Thyroid cancer is characterized by an abnormal multiplication of cells in the thyroid gland. There are several types of cancer (papillary, vesicular, medullary or follicular), the causes of which are generally unknown. Thyroid cancer is rare and has a good prognosis (about 90% of patients are cured). The diagnosis is confirmed by imaging tests and biological analyses. The treatment is based on the removal of the thyroid gland combined with iodine treatment.
Definition and Types of Thyroid Cancers
What is thyroid?
The thyroid is a small organ or gland (less than 30 grams) located at the front of the neck against the trachea. It is shaped like a butterfly with each wing forming a lobe.
Its role is to produce thyroid hormones (thyroxine or tetra-iodothyronine or T4 and tri-iodothyronine or T3) which are involved in various physiological functions and have a stimulating effect on the whole body. Most tissues will have an accelerated functioning. They are also essential for the growth and development of the skeleton and nervous system. Thyroid hormones are important and are involved in :
- The regulation of cellular metabolism;
- The control of muscular energy;
- The control of body temperature;
- Mood;
- Heart rate;
- Intestinal transit;
- The use of elements provided by food;
- Growth in children.
The secretion of such hormones is controlled via the hormone TSH (Thyroid stimulating hormone) by the pituitary gland, which is a small gland located at the base of the brain, which in turn receives orders from the hypothalamus (the region at the heart of the brain) via the hormone TRH (Thyroid stimulating hormone). When too much hormone is present in the blood, they exert a retrocontrol on its synthesis by blocking the production signal in the pituitary gland and hypothalamus.
Namely! Iodine is an essential element in the production of thyroid hormones by the thyroid gland. A regular intake, through diet (seafood, fish, iodized salt), is necessary for the proper functioning of the gland.
What is thyroid cancer?
cancer-thyroid-diagnosisThyroid cancer is characterized by an abnormal multiplication of cancer cells in the thyroid gland. In a patient with this cancer, the cells are disordered and no longer die: they form a cell mass, known as a tumour.
There are several types of thyroid cancer.
Follicular type
This type of thyroid cancer is largely in the majority since it accounts for 90% of cases and is described as “differentiated”. It develops from follicular cells, in other words, the cells that make up the tumour are very close to those of normal thyroid cells. This cancer has a very good prognosis. Under the microscope, there are two different forms:
- Papillary (80% of thyroid cancers) when the tumour has a tree-like structure;
- Vesicular when the tumour has a rounded shape. 2% of thyroid cancers also develop from follicular cells, but they are said to be “poorly differentiated”. In other words, the cells that make up the tumour have lost the characteristics of normal thyroid cells. This is called anaplastic cancer. This type of cancer develops much faster than other cancers and occurs more readily in older people.
Spinal cord type
It accounts for 8-9% of thyroid cancer cases. The tumour grows from C cells. For this type of cancer, there is a genetic predisposition. In France, it is estimated that about 3000 men and 7000 women are diagnosed each year. Women are indeed more concerned than men, particularly between the ages of 30 and 60.
Please note! As this cancer is increasingly diagnosed, its frequency seems to be increasing in the population.
In the majority of cases, the cause of the cancer is unknown. Only one cause is recognized in this type of cancer: exposure to radiation. For example, exposure to ionising radiation (repeated irradiation examinations, radiotherapy) or nuclear radiation (close nuclear tests).
In addition, there are two contributing factors: genetic predisposition or a prolonged iodine deficiency.
Symptoms, diagnosis and treatment
What symptoms?
Thyroid cancer does not cause any particular symptoms. It is usually discovered incidentally during a clinical examination, an ultrasound scan, an operation for another reason, the follow-up of a goiter (increased thyroid volume) or an already known thyroid nodule.
In the rare cases where symptoms exist, they are manifested by :
- The appearance of a nodule in the thyroid gland;
- A rapid increase in the volume of an existing goiter or nodule;
- The appearance of a ganglion in the neck;
- Voice disturbances;
- Difficulty swallowing and/or breathing.
To note! Medullary thyroid cancer, i.e. the familial form, involves an increase in the level of calcitonin (a hormone secreted by the thyroid’s C-cells to help the body eliminate calcium and phosphorus) in the blood. Thus, people at risk benefit from regular monitoring of this parameter.
What diagnosis?
During a consultation, the doctor asks the patient about various points: his thyroid medical history, the existence of possible irradiation or iodine deficiency, the presence of other pathologies and his symptoms. A complete clinical examination is then carried out with palpation of the thyroid and search for lymph nodes in the neck.
To confirm the diagnosis, the doctor prescribes additional tests:
- Blood tests in order to detect a possible thyroid dysfunction. Thyroid stimulating hormone or TSH is measured. An abnormally low level of TSH indicates hyperthyroidism, while an abnormally high level indicates hypothyroidism. Thyroid hormones can also be dosed as a supplement;
- Calcitonin and a calcium phosphorus test if the doctor suspects a medullary thyroid cancer;
- An ultrasound of the thyroid and neck;
- Cytopuncture, a painless removal of cells from the nodule for microscopic analysis. This so-called anatomopathological analysis allows the type of thyroid cancer to be determined.
- Other examinations may sometimes be necessary: thyroid scintigraphy, MRI, CT scan, etc.
What treatment?
The management of thyroid cancer depends on the type of cancer, its characteristics and the patient’s state of health. Several treatments are possible: surgery, radiotherapy or chemotherapy.
The first treatment is surgery. This is a total thyroidectomy, the entire thyroid gland is removed or even some lymph nodes. The after-effects of the operation are good, some symptoms may occur: fatigue, discomfort in swallowing, hoarseness or stiffening of the neck.
In some cases, the surgery can be supplemented by oral treatment with radioactive iodine. It destroys the potential remaining thyroid cells. For this treatment, the patient is hospitalized for a few days.
Please note! Outpatient radiotherapy is rarely prescribed for this type of cancer. Similarly, chemotherapy is little used for thyroid cancer, except in the case of anaplastic cancer or when the cancer does not respond to other treatments.
After the thyroid gland is removed, hormone treatment is started to compensate for the lack of natural thyroid hormone secretion. These are synthetic thyroid hormones (levothyroxine) to be taken for life.
Charline D., Doctor of Pharmacy