People with thyroid cancer may have questions about their prognosis and survival. Prognosis and survival depend on many factors. A doctor familiar with a person’s medical history, type of cancer, stage, characteristics of the cancer, treatments chosen and response to treatment can put all of this information together with survival statistics to arrive at a prognosis.
A prognosis is the doctor’s best estimate of how cancer will affect a person, and how it will respond to treatment. 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, and they both play a part in deciding on a treatment plan and a prognosis.
Prognostic factors are specific to each type of thyroid cancer.
Papillary and follicular thyroid cancer
Prognosis for papillary and follicular thyroid cancer is based on the AMES (Age, Metastases, Extent, Size) scoring system:
- age – Younger people have a better prognosis.
- metastatic disease – People who do not have distant metastasis at the time of diagnosis or at recurrence do better than those with metastasis.
- extrathyroidal extension – If the tumour has not grown outside the thyroid when it is diagnosed, the prognosis is better.
- size – The smaller the tumour, the better the prognosis.
Other factors may include:
- type of thyroid cancer – Papillary thyroid cancer has a slightly better prognosis than follicular thyroid cancer.
- gender – Women have a slightly better prognosis than men.
- number of tumours in the thyroid – The fewer tumours, the better the prognosis.
- spread to lymph nodes – This is controversial. Some studies show that spread to the lymph nodes is a poor prognostic factor, while other studies say it has no effect on survival.
Anaplastic thyroid cancer
Most people with anaplastic thyroid cancer have advanced disease at the time of diagnosis, and the prognosis is usually poor. The prognosis is only slightly better for those people whose tumour is less than 5 cm in diameter and can be removed by surgery.
Medullary thyroid cancer
Prognostic factors for medullary thyroid cancer include:
- age – Younger people have a more favourable prognosis.
- extent of disease at diagnosis – The more confined the tumour is to the thyroid, the better the prognosis.
- spread to the lymph nodes – The prognosis is better for those who do not have any spread to the lymph nodes.
- surgical resection – The prognosis is better if the tumour can be completely removed by surgery.
- multiple endocrine neoplasia type 2B (MEN 2B) – If the thyroid cancer is not associated with MEN 2B, the prognosis tends to be better.