Thyroid cancers occur in the cells within the thyroid gland and based on its microscopic appearance, can be differentiated in to four major sub types. These sub types will vary in its location, rapidity of its growth, spread and the prognostic outcomes. Therefore, early detection of these cancers would play a major role in the subsequent management as most of the thyroid cancers which are detected early can be treated very effectively with better prognostic benefit.
In order to make an accurate diagnosis of the type of thyroid cancer, a needle aspiration biopsy would have to be performed which will obtain a small amount of cells that needs to be investigated under the microscope. Based on these findings, the clinicians have come up with the following types of cancer.
Apart from these four, lymphoma and squamous cell type of cancer has also been detected while being investigated for thyroid pathologies. Now let us see each type separately to outline their characteristic features that would influence the management process.
Being the commonest of the thyroid cancers, it accounts for almost 70% – 80% of all thyroid cancers and can be treated easily if detected early. The condition is common among the middle aged females and it can also be detected in younger people with thyroid cancers as well. In this type, the cancer arises in the follicular cells of the thyroid and is considered to be a slow growing tumor when compared to the others.
This is the second commonest type of cancer which accounts for about 15 – 25 % and is very difficult to differentiate from the papillary type as both arise from the same follicular cells. But, the follicular type of cancer spreads mostly to distant organs such as lungs and bone through blood whereas the papillary sub type intends to spread to nearby lymph nodes. Thus, histopathological appearance would suggest the type of cancer in case it cannot be differentiated through cellular aspirate microscopy. This is also classified as a slow growing tumor and the prognosis would be better if detected early and treated.
This type of cancer arises in the parafollicular cells or C cells in the thyroid and influences the calcitonin production in these cells. The cancer has a strong genetic association and can present with a characteristic diarrhea and flushing in case of distant spread, particularly to the liver. Medullary cancers will have a poorer prognosis than papillary and follicular carcinoma even though early detection would give a better prognostic value.
Being poorly differentiated cancers of the thyroid this would be the rarest of the lot. But, it is rapidly growing and can spread to adjacent structures as well as distant organs which make it harder to treat and carry a poor prognosis.