Thyroid cancer is one of the most common cancers in Nepal. It is considered one of the, relatively, better cancers to get as deaths are rare, with a 10-year survival rate post-treatment in more than 90 percent of patients. Thyroid cancer is usually detected in its early stages and in six out of 10 patients operated on, the cancer has been confined to the thyroid.
In Nepal, national data for thyroid cancer is not available but every year, a five percent increase is assumed, with approximately 1,000-1,200 new thyroid cancer patients diagnosed annually. Tertiary-care hospitals are carrying out approximately 30-50 thyroid cancer-related surgeries per year. This growing incidence can be attributed to improved and easily-available diagnostic tools, like ultrasonography which can be conducted for non-specific throat discomfort to detect suspicious thyroid lesions. Thyroid cancer is four-to-five times more common in females than males with the 25-50 year age group most at-risk.
The thyroid gland is a vital endocrine organ that helps regulate metabolism, growth and maturation by releasing hormones into the bloodstream, specifically Triidothyronine (T3), Tetraidothyronine (T4) and calcitonin. This butterfly-shaped gland, consisting of two lobes connected by a strip of tissue, is located at the base of the neck, below the voice box.
Like any other cancer, it is caused by the abnormal growth of cells. Its cause can be multifactoral, from endemic iodine deficiency, genetic mutation, radioactive substance exposure, previous radiation therapy or various other genetic disorders.
There are four main types of thyroid cancer: papillary carcinoma (most common with 80-90 percent of cases), follicular carcinoma, anaplastic carcinoma, and medullary carcinoma.
Papillary and follicular carcinoma are also known as differentiated thyroid cancer as they grow from normal thyroid cells and are often considered as ‘good’ prognostic cancer. Papillary carcinoma, which is the most common form of thyroid cancer, grows very slowly, typically in one lobe of the thyroid gland. It often spreads to the neck’s lymph nodes over time. Despite this spreading, it is usually easily treated and rarely fatal. Follicular carcinoma also spreads to other parts of the body, such as the lungs and bones, rather than the lymph nodes. The outlook for this cancer is slightly poorer, but it is still considered better than other forms.