This study is conducted in the United States of America (USA). The aim of the study is to monitor the number of annual new adult cases of medullary thyroid carcinoma (MTC) and to establish a registry for these new cases in order to identify any possible increase related to the introduction of liraglutide, exenatide once-weekly, and other GLP-1 receptor agonists into the US market.

This active surveillance program will monitor for any signal indicating a possible association between treatment with long-acting GLP-1 RAs and the development of MTC in the United States population. Given the very low incidence of MTC in the general population, the expected rate of exposure to long-acting GLP-1 RAs, the anticipated long latency of the potential outcome under study and the limited data on underlying risk factors for development of MTC other than RET proto-oncogene mutations, an active surveillance program is the most efficient means of identifying a possible association between MTC and products in the long-acting GLP-1 RAs class. Given the uncertainty of the association of MTC in humans treated with these drugs, a study duration of at least fifteen years from the time of market introduction of the first long-acting GLP-1 RA was thought to provide evidence of an association, if one exists. If such an association is identified, a case-control study will be initiated to quantify the association.

The MTC registry is a Food and Drug Administration (FDA) post-marketing requirement for long-acting GLP-1 RA products. Because of the rarity of MTC and in order to minimize inconvenience to patients, physicians, and state cancer registries, FDA encouraged sponsors of long-acting GLP-1 RAs to work collaboratively to conduct this registry. Consequently, the MTC Registry Consortium has been formed for this purpose.

The MTC Registry Consortium refers to the Sponsors with approved long-acting GLP-1 RAs who have a contractual agreement to participate in the MTC Registry.

This active surveillance program for cases of MTC will be conducted with assistance from the North American Association of Central Cancer Registries (NAACCR). NAACCR is a collaborative umbrella organization for cancer registries, government agencies, professional organizations, and private groups in North America interested in improving the quality and use of cancer registry data. All of the central cancer registries in the U.S. and Canada are members of NAACCR, including those that participate in SEER.

Inclusion Criteria:

• A record of medullary thyroid carcinoma (MTC) identified from state/regional population-based cancer registries
• At least 18 years or older.

There are no other inclusion or exclusion criteria.

People with medullary thyroid carcinoma invited by either written invitation from the participating cancer registry or the diagnosing physician to participate in the study.

Currently this is undecided for this 15 year registry. The Data Monitoring Committee is a group of external interdisciplinary consultants who oversee the registry data to review if there are any signals or safety concerns with patients who have taken any of the long-acting GLP-1 RAs and were diagnosed with medullary thyroid carcinoma.