Thyroid cancer is usually hereditary. If you have a first degree relative who had thyroid cancer, you may be at risk for developing thyroid cancer. It can also be caused by radiation exposure in young age, like the radiation treatment to the neck to treat cancer.
Warning signs of thyroid cancer mainly include swelling of the thyroid gland with distinct nodules which are seen or felt. Sometimes thyroid cancer can spread to lymph nodes and present as lymph node swelling along the side of the neck. Sometimes a long standing swelling may suddenly increase in size and become fixed to the neck skin and muscle. In advanced cases, patients notice change in voice because of cancer involving vocal cord nerve and face difficulty in swallowing. If thyroid cancer extends into the windpipe, it may cause difficulty in breathing or noisy breathing.
85 % of thyroid cancers are well differentiated thyroid cancers called papillary cancer or follicular cancer. These are very slow growing cancers which do not affect the lifespan of the patient. Some aggressive cancers can be lethal, but early diagnosis and surgery can improve the outcome in such cases.
Thyroid cancer usually does not show up in blood work. In an aggressive variant of thyroid cancer called medullary carcinoma blood levels of calcitonin will be raised. In most cases the thyroid hormone profile may remain normal.
Thyroid cancers can remain undetected for many years as small thyroid nodules or as enlarged lymph nodes. Incidentally thyroid cancers can be detected when a patient undergoes ultrasound examination of the neck to evaluate other diseases.
If thyroid cancers are well differentiated and are left untreated, the patient may have neck swelling, but may not have any effect on the life span. Surgical treatment done early can completely cure the condition in well differentiated thyroid cancers. If left untreated cancer nodules will get bigger, may spread to lymph nodes and surrounding neck muscles. In high grade cancers, spread of cancer happens faster with spread to bone and lung.
Thyroid cancer is diagnosed with ultrasound examination of the neck which shows the characteristics of suspicious nodules. Irregular thyroid nodules with calcification in them, or abnormal lymph nodes in the neck indicate a possibility of cancer. Confirmation of the suspicion is done by Fine Needle Aspiration Cytology ( FNAC) which can diagnose well differentiated cancers. In high grade cancers like medullary cancer, blood levels of calcitonin need to be checked. In big thyroid cancers with involvement of neck lymph nodes and muscles, a PET scan or CT scan can be done to define the extent of the disease.
Most of the thyroid cancers require thyroidectomy ( removal of thyroid gland) as treatment. If the cancer has spread to lymph nodes, lymph node dissection also needs to be done. After complete removal, all tumor patients have to undergo radio iodine scan which can detect if tumor has spread to any other sites on the body in case of well differentiated cancers. If the tumor shows good radio iodine affinity, microscopic tumor which is present at the surgery site or distant site tumors can be treated by radio iodine ablation therapy. This involves drinking the radio iodine isotopes which is concentrated in the residual thyroid tissues and is thereafter destroyed by the radioactivity in the ingested medicine. This is a radiation treatment unique to thyroid cancer. Other forms of chemotherapy are available for high grade tumors and can be given based on the type of cancer.
When the thyroid gland is removed, the level of thyroxine in the body drops. This causes slow metabolism and if not treated can lead to severe hypothyroidism. So patients who undergo thyroidectomy are given thyroxine hormone as a supplement to replace the normal gland function. Also this orally taken thyroxine suppresses the cancer tissue.