Thyroid

What is the thyroid cancer follow-up?

Thyroid cancer is rare with a good prognosis, the 10-year survival rate is over 90%. It represents 1.5% of all cancers, which means approximately 8,500 new cases per year in France. The incidence rate has been increasing in the latest thirty years in industrialized countries, due to environmental factors and early diagnosis. About 75% of thyroid cancers cases affect women.

What is the thyroid cancer follow-up?

Thyroid cancer is most of the time mentioned in front of a thyroid nodule, which will be evidenced by a precautional practitioner clinical examination. It can also be revealed in an examination imageries prescribed in the first place for another reason. The patient will be asymptomatic or could have slight symptoms as: 
  • Cervical adenopathy

  • Compression signs

  • Symptoms linked to a lung or bones metastasis

Different thyroid cancer types are classed with their cellular type. 4 types of cancers are the most common:
  • Papillary (80-85% of cases)

  • Follicular (7-15% of cases)

  • Medullary (3-5% of cases)

  • Anaplastic (1-2% of cases)

Papillary cancer is one of the most common cancers. It occurs in young patients and is fortunately the one with the best prognosis.

Follicular cancer, which usually occurs in older patients, is usually associated with an aggressive clinical course, distant metastasis, and a higher mortality than papillary thyroid cancer.

Medullary cancers represent a small part of thyroid cancers and correspond histologically to a tumor that originates from C or parafollicular cells originating from the neural crest. These C cells secrete calcitonin, his immunoassay in plasma is an excellent marker of this type of cancer.

Anaplastic cancers are very rare, aggressive and are life-threatening.

Different risks according to several indicators

Cancer severity can be predicted with the cell type composition, adjacent structures invasion, his size, his vascular invasion and lymph spread node involvement.
Thyroid cancers are classified according to a TNM classification:

Tumor

  • T1 : < 2 cm, intrathyroid (T1a < 1 cm, T1b 1 à 2 cm)

  • T2 : 2 to 4 cm, intrathyroid

  • T3a :> 4 cm limited to the thyroid

  • T3b: Any size with extra-thyroid extension affecting only the muscles surrounding the thyroid (sternohyoid, sternothyroid, thyro-hyoid or omohyoid muscles)

  • T4: wide extra-thyroid extension

  • T4a : subcutaneous tissue, larynx, trachea, esophagus, recurrent

  • T4b: pre-vertebral or carotid invasion

Lymph nodes

  • N0 = No spread to local lymph nodes

  • N1 = Tumor has spread to local lymph nodes

  • N1a = Tumor has spread to lymph nodes around the thyroid

  • N1b = Tumor has spread to lymph nodes in the sides of the neck or upper chest

Metastasis

  • M0 : no distant metastasis

  • M1 : distant metastasis

Thyroid cancer, what’s next?

Different therapeutic strategies may be proposed according to the cancer type and his extension. The classic treatment will include a surgery consisting in removing the entire thyroid associated with a resection of the pre - and paratracheal nodes (level VI) on the side of the cancerous lesion. We can also associate the surgery with a radioactive iodine treatment aimed to irradiate and destroy any metastatic thyroid cells. The follow-up should be prolonged because there is a risk of recurrence.
We’ll use mainly the cervical ultrasound and thyroglobulin assay for the following-up. Thyroglobulin dosage should be practically non-existent after these treatments, it will be evaluated under stimulation with recombinant TSH to improve the sensitivity of this dosage. Indeed, after a thyroid ablation and a correct substitution of thyroid hormones, this indicator should be undetectable.

Patients will be checked 6 to 12 months after surgery and iratherapy. Depending on the examination results of this first assessment, if the thyroglobulin remains non-existent, an annual TSH and thyroid evaluation will be done. If the thyroglobulin is above the required threshold, a new irradiation or a new surgery will be recommended.

Medullary cancers following-up, which are more aggressive, require a regular clinical examination and evaluation of carcinoembryonic antigen (CEA) and calcitonin. Certain metastatic forms will require targeted therapy (radiotherapy, radiofrequency, etc.).

Thyroid cancer, what’s next?

Thyroid surgery is a common surgery coming with some risks. The intervention risks concern only 1 to 3% of cases. After the surgery, postoperative hemorrhage can occur mainly within 24-48 hours after the procedure, the main risk is a suffocating hematoma.

Transient paralysis of the nerves in this cervical area may cause dysphonia (an abnormality of the voice) or breathing issues.

If the parathyroids are affected during a total thyroidectomy, transient hypoparathyroidism is possible, and calcium and vitamin D substitute therapy will be necessary. In low cases, if this parathyroid insufficiency lasts more than 6 months, it may become permanent.

In this context, the use of fluorescence imaging (NIRAF) reduces this last post-thyroidectomy complication. Thus, the FLUOBEAM® LX medical imaging system offers real-time imaging that allows precise parathyroid localization. This technology reduces the rate of postoperative transient hypocalcemia.
Thyroid cancer is an uncommon cancer. Nowadays, if it’s taken care of on time, it offers excellent predictions. However, the follow-up should be done for a long term because of the risk of recurrence.