Papillary thyroid cancer (PTC) is the most frequently diagnosed form of thyroid cancer, originating from the follicular cells within the thyroid gland. This type of cancer often grows slowly and has a generally favorable prognosis. While the majority of papillary thyroid cancer cases arise sporadically, meaning they are not inherited, a smaller proportion of cases can have a hereditary component, occurring in families.
Understanding Papillary Thyroid Cancer and Heredity
Familial papillary thyroid cancer refers to instances where multiple family members are affected by the disease, indicating a potential shared genetic predisposition or common environmental factors within the family. Familial cases represent a smaller segment of all papillary thyroid cancers, estimated to be around 5% to 10% of diagnoses. While a family history of thyroid cancer, particularly PTC, can increase an individual’s risk by five to ten times, it does not automatically confirm a direct inherited gene is involved in every familial cluster. Familial PTC may sometimes manifest at an earlier age compared to sporadic cases and can be associated with a higher likelihood of multifocal tumors.
Genetic Factors and Inheritance Patterns
Hereditary papillary thyroid cancer is linked to germline mutations, which are genetic alterations present in nearly every cell of the body and can be transmitted from a parent to their offspring. These mutations increase an individual’s susceptibility to developing PTC, though they do not guarantee cancer development. The inheritance pattern for many of these conditions is autosomal dominant, meaning only one copy of the altered gene from either parent is sufficient to increase the risk.
Specific genetic syndromes are associated with an elevated risk of PTC:
Mutations in the PTEN gene are linked to Cowden syndrome, which increases the risk of various cancers, including breast and thyroid cancers.
Mutations in the APC gene are found in Familial Adenomatous Polyposis (FAP), also associated with an increased risk of papillary thyroid cancer.
Other genes, such as DICER1, are recognized in familial nonmedullary thyroid cancer syndromes.
Some familial PTC cases are associated with genes like WDR77.
Genetic Testing and Family Screening
Genetic testing for hereditary papillary thyroid cancer may be considered in specific situations. These include cases of early-onset PTC, the presence of multiple tumors (multifocal disease), aggressive disease characteristics, or a strong family history of thyroid cancer or related genetic syndromes. The testing typically involves analyzing a blood or saliva sample to identify specific germline mutations.
Genetic counseling is an important step both before and after testing. A genetic counselor can help individuals understand the implications of testing, interpret results, and discuss potential risks for family members. For families where a hereditary predisposition to PTC is identified, screening recommendations for relatives might include regular thyroid ultrasounds or clinical examinations. These personalized decisions regarding genetic testing and ongoing surveillance should always be made in close consultation with healthcare professionals.