On World Thyroid Day, Associate Professor Michael Elliott gives an overview of advances in treatment of thyroid cancer – the cancer with a 96 per cent survival rate up to five years that is now more common than it was three decades ago.
Thyroid cancer is found in the thyroid gland, which makes hormones that regulate the body’s metabolism. Symptoms include a lump in the neck, difficulty swallowing or breathing, or a hoarse voice.
An exponential increase in the incidence of thyroid cancer started nearly 30 years ago. In 1990 the incidence per 100 000 people for males was 1.7 and females was 5.1. In 2012, the incidence per 100 000 people in males was 6.6 and females was 19.1.
We believe this increase in incidence is largely due to increased detection as most of the thyroid cancers detected are small, less than two centimetres, and being diagnosed due to the incidental finding of thyroid nodules with the increase use of neck ultrasound, CT scan, MRI scan and PET-CT scans.
During this same time period, there has been a clear shift away from aggressive management of thyroid cancer. Traditionally the standard treatment was total thyroidectomy (with or without neck dissection), radioactive iodine and thyroid hormone suppressive treatment. Fast forward to contemporary management and we are now much more selective with respect to extent of surgery, lower doses of radioactive iodine or no radioactive and less aggressive thyroid hormone suppression.
In Japan, there are good studies showing that thyroid cancers smaller than one centimetre may even be safely treated with no surgical intervention at all.
Fortunately, most patients have well differentiated (cancer cells that look and behave more calmly like normal cells) thyroid cancer and do exceptionally well. It is rare for a patient to die from well differentiated thyroid cancer.
Although papilliary thyroid cancer accounts for most cases of thyroid cancer, it is other types, such as medullary, poorly differentiated and anaplastic thyroid cancer, that comprise the bulk of thyroid related death. Anaplastic thyroid cancer is almost universally fatal with a short life span once diagnosed.
New medical treatment options that can help patients with widely systemic disease, however, are showing promise. When appropriately managed, well differentiated thyroid cancer has an excellent prognosis – even for patients that develop a recurrence.