The thyroid is a two-lobed, butterfly-shaped endocrine gland that plays a vital role in regulating various bodily functions, including metabolism, brain function, heart health, bone development and the gastrointestinal tract. Therefore, early detection of it having cancer is of paramount importance so that treatment can be administered effectively.
As per the data available, the incidence of thyroid cancer is 5.4 per lakh population of India. Genetic predisposition is one of the potential risk factors, as thyroid cancer often runs in families. Another risk that increases the occurrence of thyroid cancer is exposure to therapeutic or environmental radiation in childhood. Residing in iodine-deficient or iodine-excess geographical zones also carries the risk of developing thyroid cancer. Patients with pre-existing goitre (swelling of the thyroid gland) – either a solitary nodule or multinodular goitre – are susceptible to malignant transformation in 20 percent of cases.
There are four types of thyroid cancers based on their histopathological (a medical term for the diagnosis and study of diseases of the tissues) classification. Papillary thyroid carcinoma usually presents as a painless lump or nodule on the thyroid gland. Follicular thyroid carcinoma does not usually spread to nearby lymph nodes but is more likely to spread to other organs, like the lungs or bones. Medullary thyroid carcinoma develops from C-cells in the thyroid gland. Lastly, anaplastic thyroid carcinoma looks the least like normal thyroid gland cells and is an extremely aggressive form of cancer that spreads quickly.
Papillary and follicular thyroid carcinomas are called well-differentiated thyroid cancers (the cells of the thyroid gland look closer to normal) and have an excellent prognosis if recognised and treated on time. Medullary thyroid carcinoma is a poorly differentiated thyroid cancer (the thyroid gland cells look more abnormal) and is harder to treat, and anaplastic thyroid carcinoma is an undifferentiated thyroid cancer that has the worst prognosis as symptoms progress rapidly.
Papillary thyroid carcinoma often affects those in the younger age group between 30 to 50 years, whereas follicular thyroid carcinoma affects those above 50 years of age and together are the most commonly presented thyroid carcinomas.
Thyroid cancer may not display any symptoms in the critical stages when detection and treatment are paramount. It is usually presented as painless swelling in the midline of the neck. There might be a sudden increase in the size of the thyroid gland associated with iodine deficiency, resulting in difficulty in swallowing and breathing. A change in voice may also be noticeable. A strong suspicion of thyroid cancer arises when the goitrous thyroid gland is associated with a lymph node swelling at the side of the neck.
To detect thyroid cancer, two basic investigations are recommended. The first is the thyroid ultrasonography (thyroid USG), and the second is Fine Needle Aspiration, a procedure that removes a small tissue sample from the thyroid gland for analysis. Cytology (a branch of pathology that deals with the functioning and structure of cells) of the thyroid swelling, under USG guidance, is recommended, and based on peculiar findings on the ultrasound and fine needle aspiration cytology (FNAC), thyroid malignancy can be detected but not confirmed.
Well-differentiated thyroid cancers, like papillary or follicular thyroid carcinomas, carry with them an excellent prognosis with a total thyroidectomy (surgical removal of the thyroid gland). The surgery needs to be followed by radioactive iodine ablation (a minimally invasive medical procedure used to destroy abnormal body tissue) of the residual post-operation thyroid pathology. The patient is then started on a higher suppressive dose of thyroxine which suppresses the production of thyroid-stimulating hormone (TSH).
A diagnostic radioiodine test should be conducted after six months post-surgery to detect the presence of thyroid cancer. For any further reduced thyroid disease and if present in ablation by therapeutic radioactive iodine dose, the patient needs to do an early follow-up to detect the presence of residual thyroid cancer.
Recurrence of thyroid cancer is detected from increased serum TG (thyroglobulin level), as thyroglobulin is a protein secreted by the thyroid gland. Raised levels of TG are seen in recurrent Thyroid malignancy and also in the inflammation of Thyroid gland, ( Thyroiditis). These tests are often used for postoperative surveillance of patients with well-differentiated thyroid cancer.
Similarly, serum calcitonin is a very sensitive tumour marker for patients with medullary thyroid carcinoma. Untreated thyroid cancer eventually shows metastasis (movement or spread of cancer cells from one organ or tissue to the other) to lungs and bones.
One ought to do a thyroid screening or check-up if there is a goitre in the patient’s neck, with quicker evaluation in the form of USG or CT scan recommended depending on the swelling’s size. A check-up should also be done if there are symptoms of hypothyroidism (underperformance of the thyroid gland) or hyperthyroidism (over-performance of the thyroid gland). Basic blood tests for the thyroid gland include testing for Free T3/Free T4 and TSH levels. Any aberration in these tests indicates a thyroid disease and appropriate treatment from the physician is recommended.
As per available reports, seven per cent of the Goan population suffers from hypothyroidism and nearly 60 per cent were not aware they were afflicted with the disease; hence, regular overall check-ups are a must as a preventative measure.
(The writer is consultant ENT and Head and Neck Surgeon at Healthway Hospitals, Old Goa)