WHAT IS THYROID CANCER?
Thyroid cancer is a cancerous tumour that forms in the thyroid gland. The thyroid gland is a butterfly-shaped organ usually located in the lower front aspect of the neck. The main function of the thyroid gland is to make the thyroid hormones Thyroxine (T4) and Tri-iodothyronine (T3), which are secreted into the blood and carried to every tissue in the body. T4 and T3 help the body regulate metabolism, use energy, stay warm, and keeps the brain, heart, muscles, and other body organs working normally.
According to Cancer Research UK (CRUK), there were 3500 new cases of thyroid cancer in the UK in 2015. Thyroid cancer is more common in females than males (at a ratio of 3:1) and usually after the age of 30, although it can affect any age group.
TYPES OF THYROID CANCER
Thyroid cancer includes a variety of tumours with different biological behaviours. The vast majority, over 90%, are well differentiated thyroid cancer of which most (85%) are papillary thyroid cancer (PTC), and the remaining (15%) follicular thyroid cancer (FTC).
Papillary thyroid cancer tends to occur in younger patients and is more likely to spread to lymph nodes in the neck. Follicular thyroid cancer is more common in middle aged patients, and if it spreads outside the thyroid, tends to involve distant body sites such as the lungs and bone. Following treatment, the prognosis of well differentiated thyroid cancer is excellent, with the expectation that over 95% of patients will be cured, especially if they are under 55 years of age and female.
Other much less common forms of thyroid cancer include Medullary Thyroid Cancer (MTC), Hurthle Cell Thyroid cancer (HCTC), Poorly Differentiated Thyroid Cancer, and Anaplastic Thyroid Cancer. These types of thyroid cancer are more aggressive and, in some cases, for example Anaplastic Thyroid Cancer, have a very poor prognosis even with treatment.
SYMPTOMS OF THYROID CANCER
The most common symptom is painless lump in the neck, usually in the thyroid gland, or less often an enlarged lymph node. A lump in the thyroid gland is also known as a thyroid nodule, and up to 75% of the population may have a thyroid nodule, but less than 1% are cancerous.
Most thyroid nodules are not palpable by patients, and instead are identified incidentally during routine clinical examination or X-rays/body scans performed for other reasons. Less common presenting symptoms of thyroid cancer include hoarseness, voice change, swallowing and/or breathing difficulty
RISK FACTORS FOR THYROID CANCER
Thyroid cancer is 6.6 times more likely in patients with a first degree relative that has the disease, compared to the general population, according to CRUK. Exposure to ionising radiation from radiotherapy in childhood or nuclear accidents also increases the risk of thyroid cancer in later life. Being overweight or obese is also a recognised risk factor for thyroid cancer with a 10% to 27% increased chance of developing the disease compared to normal individuals.
DIAGNOSIS OF THYROID CANCER
If there is a suspicion or the need to exclude thyroid cancer, your GP or doctor will refer you to a head and neck or thyroid surgeon for further assessment and treatment. Your surgeon will take a detailed clinical history and perform a comprehensive physical head and neck examination including an evaluation of your voicebox using a small camera (endoscope) that is painlessly passed through the nose. Following this assessment, you will require blood tests to check your thyroid function, and your surgeon will refer you for an ultrasound guided biopsy of the suspicious thyroid nodule.
The radiologist will provide an ultrasound report on their level of suspicion as to the cancerous nature of the thyroid nodule and should also comment on whether there are any other thyroid nodules of concern, or lymph glands in your neck that are abnormally enlarged. The radiologist may then perform a fine needle aspiration biopsy (FNAB) of suspicious thyroid nodules or neck glands. FNABs are relatively painless and well tolerated by most patients.
A pathologist with special training in thyroid biopsies will analyse the FNAB and produce a report stating whether the thyroid nodule is benign, indeterminate, or highly suspicious for thyroid cancer. Depending on the biopsy results, further investigations such as an MRI scan of the neck and chest X-ray may be required. Thyroid nodules indeterminate or suspicious for thyroid cancer on biopsy will usually require thyroid surgery (please see section on thyroid surgery).
Mr Ofo is an experienced thyroid cancer surgeon and also a core member and lead clinician of the combined St George’s Hospital & Royal Marsden Hospital London Thyroid Cancer Multidisciplinary team (MDT). He works very closely with radiologists, endocrinologists and pathologists at St George’s and Kingston Hospitals, as well as oncologists from the Royal Marsden Hospital.
Mr Ofo also offers a one stop diagnostic thyroid and neck lump clinic at the New Victoria Hospital on Tuesday evenings, whereby patients with neck lumps will have a comprehensive clinical assessment by Mr Ofo, followed by an ultrasound scan of the neck +/- biopsy by a dedicated head and neck radiologist, and on the spot reporting of the biopsy specimen by a dedicated head and neck pathologist. The biopsy result is communicated to patients by Mr Ofo at the same consultation, alleviating the anxiety of waiting for a diagnosis, or needing additional clinic consultations to discuss biopsy results.
Thyroid surgery for cancer usually involves removal of the whole thyroid gland plus or minus lymph glands in the thyroid bed or neck (central or lateral neck compartment) if these lymph nodes are suspicious or confirmed to have thyroid cancer cells within them. In low risk patients (younger age, well differentiated thyroid cancer) with no lymph node involvement, there is a trend towards less invasive surgery and patients may be offered partial or hemithyroidectomy only, with completion thyroid surgery performed if there are concerns on pathology assessment from the initial thyroid operation.
Depending on the extent of thyroid cancer, further treatment after surgery with radioiodine may be required. There are potential risks from radioiodine therapy, hence it is only offered if the MDT believes that a patient will benefit from it. However, patients will always get the opportunity to discuss the pros and cons of postoperative radioiodine with an oncologist before commencing treatment.
POST TREATMENT SURVEILLANCE
Thyroid cancer patients usually require long term follow up for many years after treatment. The need for blood tests to check thyroid hormone, calcium, parathyroid hormone and thyroglobulin levels, or additional scans with ultrasound +/- radioiodine, will depend on the extent of disease and treatment received. You will be advised by your head and neck surgeon on the required follow-up regimen and which clinician (oncologist or surgeon) will take the lead on your follow-up.
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