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Medullary vs Papillary Thyroid Cancer

Explore the distinctions between medullary and papillary thyroid cancers in terms of origin, genetics, spread, and outlook. Learn symptom identification and treatment choices.

Thyroid cancer occurs when abnormal cells grow uncontrollably in the thyroid gland, forming a tumor. While all thyroid cancers originate in the same organ, key differences exist between the two most common types – follicular thyroid cancers and medullary thyroid cancer. Understanding their unique risk factors, genetics, symptoms, outlooks, and tailored therapies empowers patients to confront the disease.

What is Thyroid Cancer?

Thyroid cancer is a type of cancer that originates in the thyroid gland, a small, butterfly-shaped gland located at the front of the neck under the skin. The thyroid gland is part of the endocrine system and plays a crucial role in regulating the body’s metabolism, growth, and development by producing and releasing specific hormones. Thyroid cancer occurs when abnormal cells in the thyroid gland grow and multiply uncontrollably, forming a tumor. There are several types of thyroid cancer, including papillary, follicular, medullary, and anaplastic thyroid cancer. Each type has distinct characteristics and requires different treatment approaches.

Types of Thyroid Cancer

There are four main types of thyroid cancer: papillary, follicular, medullary, and anaplastic. Papillary thyroid cancer is the most common type, accounting for about 80% of all thyroid cancer diagnoses. It typically grows slowly and often spreads to lymph nodes in the neck. Follicular thyroid cancer is the second most common type, making up about 10% of all thyroid cancer cases. This type can sometimes spread to other parts of the body, such as the lungs and bones. Medullary thyroid cancer is a rare type, accounting for about 3-5% of all thyroid cancer diagnoses. It originates from the C cells of the thyroid gland and can be associated with genetic syndromes. Anaplastic thyroid cancer is the least common type, representing about 1% of all thyroid cancer diagnoses. It is an aggressive form of cancer that grows rapidly and is challenging to treat.

Key Differences Between Medullary and Papillary Thyroid Cancers

Medullary thyroid cancer accounts for about 4% of all thyroid cancer cases, while papillary thyroid cancer makes up around 80%. Here are some of the main differences between the two:

Origins: Medullary thyroid cancer begins in the C cells of the thyroid which produce calcitonin hormone. Papillary cancer begins in follicular cells of the thyroid that are responsible for making thyroid hormones.
Gender predilection: Medullary cancer affects men and women equally. Papillary cancer is 3 times more common in women.
Genetics: Medullary cancer can be inherited. Most papillary cancers occur sporadically.
Spread: Medullary cancer can spread to lymph nodes, lungs, liver, and bones. Papillary cancer typically metastasizes to nearby lymph nodes first.
Prognosis: Medullary cancer has a less favorable outlook compared to papillary thyroid cancer.

Recognizing the Symptoms

In the early stages, both medullary and papillary thyroid cancers may not cause any noticeable symptoms. As the tumors grow larger, some common signs can include:

A visible lump or nodule in the front of the neck
Swollen lymph nodes in the neck
Hoarse or changing voice
Difficulty breathing or swallowing
Chronic cough (not due to cold)
Enlarged lymph nodes: Monitoring for enlarged lymph nodes is crucial during follow-up examinations for medullary thyroid cancer (MTC) patients. These enlarged lymph nodes can indicate cancer recurrence or metastasis and should be evaluated carefully, particularly if they are non-tender, firm, and do not shrink over time.

Medullary cancer can sometimes cause diarrhea or flushing episodes. Symptoms depend on the extent of tumor spread. Many cases are diagnosed incidentally during imaging tests for other neck or chest issues.

How Medullary and Papillary Thyroid Cancers Are Diagnosed

If a thyroid nodule is detected during a physical exam or imaging study, doctors will investigate further to determine if it is cancerous. Typical diagnostic steps include:

Blood tests – to check levels of thyroid hormones and tumor markers like calcitonin
Imaging – ultrasound, CT scan, MRI, or PET scan to visualize the thyroid and surrounding region
Biopsy – fine needle aspiration or surgical biopsy to extract cells for examination under a microscope
Genetic testing – for medullary thyroid cancer to look for RET gene mutations

These tests help confirm the diagnosis and determine the cancer type – medullary or papillary. Staging exams are then done to assess the spread of the disease. Persistent medullary thyroid cancer, characterized by ongoing evidence of the disease following initial treatment, often requires specialized care at dedicated clinics due to its complexity and the need for tailored therapeutic approaches.

Risk Factors and Causes

Certain factors can raise one’s risk of developing thyroid cancer: genetic mutations, particularly in the RET proto-oncogene, play a significant role in developing medullary thyroid cancer. These mutations can be inherited or occur spontaneously, and individuals with a family history of multiple endocrine neoplasia type 2 are at a higher risk.

Medullary Thyroid Cancer

Family history – 25% of cases are inherited due to RET gene mutations
Multiple endocrine neoplasia – Multiple endocrine neoplasia type 2 (MEN2) is an inherited condition that significantly increases the risk of developing medullary thyroid cancer (MTC), especially in younger individuals. Genetic testing for the RET proto-oncogene is crucial for individuals at risk due to familial links.
Radiation exposure – controversial and not a proven cause

Papillary Thyroid Cancer

Radiation exposure – especially in childhood
Family history – 5-10% of cases are inherited
Unhealthy weight – obesity increases risk in women
A diet low in iodine – can cause thyroid dysfunction
Breast cancer – papillary thyroid cancer risk is higher in survivors

Though both cancers affect the thyroid, their causes, and risk factors differ considerably.

Treatment Approaches for Each Type

Treatment plans are tailored based on the type of thyroid cancer, its stage, and the patient’s overall health profile. For advanced medullary thyroid cancer, treatment options may include chemotherapy or radiation therapy, especially when the disease has invaded surrounding structures.

Medullary Thyroid Cancer Treatment

As medullary thyroid cancer can spread aggressively, the primary treatment is the surgical removal of the entire thyroid gland and surrounding lymph nodes. Additional therapies include:

Targeted drug therapy – using tyrosine kinase inhibitors like vandetanib and cabozantinib
Immunotherapy – to stimulate the immune system against cancer cells
Radiation therapy – for pain relief and reducing tumor size
Chemotherapy – can be combined with radiation in advanced stages

Papillary Thyroid Cancer Treatment

Most papillary thyroid cancers have an excellent prognosis with treatment. Usual therapies include:

Radioactive iodine therapy – to destroy any remaining thyroid tissue after surgery
Thyroid hormone therapy – to replace hormones no longer made by removed thyroid
Targeted therapy – rarely needed for advanced papillary thyroid cancers

Prognosis and Outlook

Thyroid cancer survival rates can vary substantially based on the type, stage at diagnosis, and effectiveness of treatment. Medullary thyroid carcinoma (MTC) is a specific type of thyroid cancer that is often associated with genetic factors, making early detection and genetic counseling crucial for effective management.

Medullary Thyroid Cancer Prognosis

If detected early when still localized, the 5-year survival rate for medullary thyroid cancer is over 99.5%. However, the rate drops to 92% for regional disease and 43% for metastatic cancer. Periodic monitoring and early intervention for recurrence are critical.

Papillary Thyroid Cancer Prognosis

Papillary thyroid cancer has an excellent prognosis overall. The 5-year relative survival rate is over 99.5% for localized tumors and 99% for regional stage disease. Even if spread to distant lymph nodes and organs occurs, 5-year survival remains high at 74%.

Younger age, small tumor size, and minimal spread indicate more favorable outcomes for both cancer types.

Likelihood of Recurrence

Cancer recurrence means the disease has come back after treatment. Monitoring for possible recurrence is a lifelong process for thyroid cancer survivors.

For medullary thyroid cancer, the recurrence risk is estimated to be up to 50% even with successful surgery. Recurrence usually happens within the first 2-3 years after initial treatment.

Recurrence rates for papillary cancer range from 8-28% depending on initial tumor characteristics like size, spread to lymph nodes, and cancer genetics. Periodic long-term follow-up exams are recommended to detect any recurrence or new tumors early when they are most treatable.

Genetics Behind Thyroid Tumors

Genes influence risk for both medullary and papillary thyroid cancers.

Around 25% of medullary thyroid cancer cases are inherited through autosomal dominant transmission of the RET gene mutation from a parent. Sporadic mutations also occur. Monitoring thyroid stimulating hormone (TSH) levels is crucial in patient management following thyroid surgery, particularly after a thyroidectomy, to ensure they are within normal ranges and to manage TSH levels in medullary thyroid cancer patients.

For papillary thyroid cancer, the BRAF gene mutation and RET/PTC rearrangements are the most common genetic changes identified in tumor cells. Overall, genetics contribute to 5-10% of cases.

Follow-up Care

Follow-up care is essential for patients with medullary thyroid cancer to monitor for recurrence and manage any potential side effects of treatment. After surgery, patients will need to take thyroid hormone replacement medication for life to replace the hormones that the thyroid gland normally produces. Regular follow-up appointments with a healthcare provider will include physical exams, blood tests to check thyroid hormone levels, and imaging tests such as ultrasound or CT scans to monitor for any signs of recurrence. Patients with medullary thyroid cancer will also need to have their calcitonin and CEA levels checked regularly to monitor for any changes that may indicate recurrence. This comprehensive follow-up care ensures that any recurrence is detected early and managed promptly, improving the overall prognosis for medullary thyroid cancer patients.

Medical Terms to Know

Adenocarcinoma: A type of cancer that starts in cells that line organs and glands.
C cells: Cells in the thyroid gland that produce calcitonin.
Follicular cells: Cells in the thyroid gland that make thyroid hormones.
Genetics: The study of genes and how they influence inherited traits.
Hormones: Chemicals that are produced by glands in the body and travel through the bloodstream to organs and tissues, where they have specific effects.
Iodine: A mineral that is essential for the production of thyroid hormones.
Metastasis: The spread of cancer cells from one part of the body to another.
Papillary thyroid cancer: A type of thyroid cancer that starts in the follicular cells.
Prognosis: The outlook for a disease based on its expected course and outcome.
Thyroid gland: A small gland in the neck that produces hormones that help regulate metabolism, growth, and development.
Thyroid hormone: A hormone that is produced by the thyroid gland and helps regulate metabolism, growth, and development.

Key Takeaways

Though both are thyroid cancers, medullary and papillary types start from different cell origins and have varying risk factors, behavior, and prognoses.

Papillary cancer is far more common and typically has better outcomes, while medullary cancer can be more aggressive, spreading to distant organs.

Treatment options include radioiodine therapy, thyroid ablation, or radiation may be used as needed for tumors.