Thyroid Cancer

Thyroid Cancer

Overview

  • Thyroid cancer refers to cancer that develops within the thyroid, a gland found at the front of the neck.
  • The thyroid is primarily made up of two types of cells:
    1. Follicular cells – these produce and store the hormones T3 (triiodothyronine) and T4 (thyroxine) and the protein Tg (thyroglobulin)
    2. Parafollicular cells (C-cells) – these produce the hormone calcitonin, which helps control calcium levels in the body
  • Thyroid cancer is often classified by the type of cell the cancer develops from and can be differentiated or undifferentiated thyroid cancers

Classification

The four types of thyroid cancer include:

  • Papillary thyroid cancer – slow-growing cancer that develops from the follicular cells in the thyroid. This is the most common type of thyroid cancer, accounting for 70-80% of all thyroid cancer diagnoses
  • Follicular thyroid cancer – cancer that also develops from the follicular cells in the thyroid. This accounts for 15-20% of all thyroid cancer cases and includes Hürthle cell carcinoma
  • Medullary thyroid cancer – an often hereditary cancer that develops from the parafollicular cells in the thyroid. This accounts for 4-5% of all thyroid cancer diagnoses and can be associated with tumours in other glands
  • Anaplastic thyroid cancer – rare fast growing cancer that develops from the follicular or parafollicular cells in the thyroid. This accounts for 1-2% of all thyroid cancer cases and typically occurs in people over the age of 60

Risk Factors

  • Exposure to ionising radiation is a risk factor for papillary carcinomas, when exposure has occurred at a younger age. An increased incidence of thyroid cancer in children and adolescents was seen in Ukraine, Belarus and certain regions of Russia as early as four years after the Chernobyl accident. Thyroid carcinoma may first appear 20 or more years after radiation exposure.

Other risk factors include:

  • History of goitre,
  • Thyroid nodule or thyroiditis,
  • Family history of thyroid disease,
  • Female gender and
  • Asian race.
  • Genetics: approximately 20-25% of MTC are hereditary because of mutations in the RET proto-oncogene. Mutations in the RET gene cause multiple endocrine neoplasia type 2 (MEN 2), which is an autosomal dominant disorder associated with a high lifetime risk of MTC.

What are the signs and symptoms?

Some of the significant symptoms are:

  • Most commonly, a lump or a swelling in the neck
  • Difficulty in swallowing
  • Change in voice or hoarseness in voice
  • Irritating cough without any symptom of cold or other reason
  • Breathing difficulty often with a wheezing sound while breathing

Evaluation

  1. Blood tests
    • Thyroid Function Tests should be performed for any patient with a thyroid nodule.
    • However, TFTs (most patients will be euthyroid) and thyroglobulin (Tg) measurement are of little help in the diagnosis of thyroid cancer.
    • Serum calcitonin is a reliable tool for the diagnosis of MTC (5-7% of all thyroid cancers).
  2. Ultrasound
    • Thyroid ultrasound is extremely sensitive for thyroid nodules and is used as a first-line diagnostic procedure for detecting and characterising nodular thyroid disease.
    • Ultrasound features associated with malignancy include hypoechogenicity, microcalcifications, absence of peripheral halo, irregular borders, solid aspect, intranodular blood flow and shape (taller than wide).
    • Ultrasound should also be used to explore the neck carefully to assess the status of lymph node chains.
  3. Fine-needle aspiration cytology (FNAC)
  4. The results of FNAC are very sensitive for the differential diagnosis of benign and malignant nodules

    Radionuclide imaging: Distinguishing functioning toxic nodules and thyroid metastases from follicular and papillary carcinomas is best with 123iodine uptake studies:

    • Normal iodine uptake is seen in 'warm' nodules. Lesions that take up excessive amounts of iodine are called 'hot' and those that do not take it up are called 'cold'.
    • CT, PET CT and MRI scan: CT scans and MRI scans are valuable to detect local and mediastinal spread and regional lymph nodes.

Treatment options

  • Solitary thyroid nodules that are malignant, suspicious or indeterminate on FNA, require surgery
  • Patients with suspicious nodule need to undergo hemithyroidectomy with intra operative frozen section and based on the report if malignant, may need total thyroidectomy
  • Diagnosed cases of differentiated thyroid cancers may need total thyroidectomy + neck dissection of central compartment as required
  • Radioiodine remnant ablation and therapy is done for a few cases of differentiated thyroid cancer
  • Adjuvant external beam radiotherapy for differentiated thyroid cancer should be considered for patients with a high risk of recurrence
  • Newer targeted therapies are advised for recurrent or metastatic radio iodine refractory thyroid cancers

What we offer in our centre?

All of the above treatment options are available in our centre

Surgeries including

  • Hemithyroidectomy
  • Total thyroidectomy +/- central compartment neck dissection
  • Minimally invasive parothyroidectomy
  • Frozen section analysis for immediate diagnosis of suspicious nodules.

Adjuvant therapies

  • Radioactive iodine- uptake scan and ablation of thyroid neoplasm, if necessary
  • Radiation therapy for advanced thyroid tumours
  • Targeted therapy for metastatic / anaplastic thyroid malignancies

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