If you have thyroid cancer, you may have questions about your prognosis. A prognosis is the doctor’s best estimate of how cancer will affect someone and how it will respond to treatment. Prognosis and survival depend on many factors. Only a doctor familiar with your medical history, the type, stage and characteristics of your cancer, the treatments chosen and the response to treatment can put all of this information together with survival statistics to arrive at a prognosis.
A prognostic factor is an aspect of the cancer or a characteristic of the person that the doctor will consider when making a prognosis. A predictive factor influences how a cancer will respond to a certain treatment. Prognostic and predictive factors are often discussed together. They both play a part in deciding on a treatment plan and a prognosis.
The following are prognostic and predictive factors for thyroid cancer.
The type of tumour is the most important prognostic factor for thyroid cancer. Papillary carcinoma has the best outcome and most favourable prognosis. It tends to respond well to treatment. Follicular carcinoma or medullary carcinoma has a good prognosis, but less favourable than papillary carcinoma. Anaplastic carcinoma has a very poor prognosis.
Age is an important prognostic factor for differentiated thyroid cancer (papillary and follicular carcinomas). People under 40 years of age have a more favourable prognosis.
The lower the stage at diagnosis, the better the prognosis. Tumours that are larger than 4 cm or have grown through the thyroid to surrounding tissues and structures have a less favourable prognosis. Thyroid cancer that has spread to other parts of the body (called distant metastases) also has a less favourable prognosis.
People who have medullary carcinoma associated with the hereditary condition MEN2B tend to have a poor prognosis. They are often diagnosed with more advanced thyroid cancer.