If thyroid cancer is not treated, the tumor may continue to grow, leading to airway compression, swallowing difficulties, and voice changes. Untreated cancer can spread to lymph nodes and distant organs, worsening the prognosis.
Papillary thyroid cancer, though usually slow-growing, can still metastasize if ignored. Advanced stages may cause neck pain, enlarged lymph nodes, and local tissue invasion, increasing treatment complexity and risk.
More aggressive thyroid cancers, such as anaplastic or medullary types, progress rapidly without treatment. Patients may develop life-threatening complications within months, making timely medical care essential.
Early treatment significantly improves survival rates. Surgery, radioactive iodine, and targeted therapies provide effective management, preventing irreversible complications and enhancing quality of life.
Prof. Dr. Özgür KILIÇKESMEZ Prof. Dr. Kılıçkesmez holds the Turkish Radiology Competency Certificate, the Turkish Interventional Radiology Competency Certificate, Stroke Treatment Certification, and the European Board of Interventional Radiology (EBIR). In his academic career, he won the Siemens Radiology First Prize in 2008.
Interventional Radiology / Interventional Neuroradiology
What Are the Potential Symptoms of Untreated Thyroid Cancer?
When thyroid cancer is left untreated, various symptoms may emerge as the disease progresses, and these symptoms can vary depending on the course of the disease. Initially, patients may notice a palpable mass or swelling in the neck area. This mass may grow over time, becoming more pronounced and, if untreated, pressing on surrounding tissues. Tumor enlargement can also lead to hoarseness or changes in the voice.
In some patients, the tumor may press on the esophagus, causing difficulty swallowing and pain when eating. On the other hand, pressure on the windpipe can lead to respiratory problems such as shortness of breath, which may become more pronounced during physical activity.
In addition, swelling of the lymph nodes is a common symptom, as cancer cells can spread to the lymphatic system. Pain is also a result of metastasis and is typically concentrated in the neck or throat region. Depending on the size and location of the tumor, a persistent cough, especially dry and independent of other respiratory diseases, may occur.
As symptoms progress and the cancer spreads beyond the thyroid to other organs, systemic symptoms develop. When the spread reaches the bones or lungs, severe bone pain and persistent fatigue may become prominent. In advanced stages of cancer, these symptoms occur more frequently and severely.
How Does Untreated Thyroid Cancer Spread to Other Parts of the Body?
If thyroid cancer is left untreated, cancer cells can spread to other parts of the body through the lymphatic system and bloodstream. This dissemination accelerates disease progression and complicates treatment. Especially via the lymphatic system, cancer cells primarily reach the lymph nodes in the neck region.
Lymphatic System: Lymph nodes are the most common sites of thyroid cancer spread. Through the lymphatic system, cancer cells are transported to the neck lymph nodes, which play a key role in tumor dissemination. Papillary thyroid cancer, in particular, has a tendency to spread to these lymph nodes. Cancer cells that reach the lymph nodes can multiply there and spread to other parts of the body.
Thyroid cancer can also spread to distant organs through the bloodstream, making it more dangerous. Cancer cells that enter the bloodstream may settle in organs such as the lungs and bones. This type of spread usually occurs at more advanced stages and becomes more resistant to treatment.
- Hematogenous spread of thyroid cancer to the lungs can cause serious symptoms such as shortness of breath, cough, and chest pain.
- Especially in follicular and medullary thyroid cancer, cancer cells may cause bone pain and fractures.
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What Is the Likelihood of Thyroid Cancer Becoming Fatal If Untreated?
The likelihood of thyroid cancer becoming fatal if left untreated depends on the type of cancer and the stage of the disease. Aggressive types such as anaplastic thyroid cancer (ATC) can become rapidly fatal if not treated. ATC is usually detected at advanced stages and the average survival is only about 6 months. If not rapidly treated, this cancer can spread to critical organs such as the airways, threatening vital functions. Less than 20% of ATC patients survive more than 1 year without treatment.
On the other hand, more common and slow-growing types such as papillary thyroid cancer (PTC) usually have a better prognosis. However, if left untreated for a long time, these cancers can also metastasize to other parts of the body, increasing disease severity. Even though PTC initially progresses slowly, it can reduce survival rates if not treated. In the end, even PTC can become fatal and significantly affect quality of life due to metastasis.
Early diagnosis and rapid treatment are crucial, especially for aggressive types such as ATC:
- ATC can quickly spread to surrounding tissues and affect critical organs.
- If left untreated, it can cause death by obstructing the airways.
For both types, delaying treatment carries serious risks. Whether it is slow-growing PTC or aggressive ATC, untreated thyroid cancer can lead to fatal outcomes.
How Does Untreated Thyroid Cancer Affect Quality of Life?
If left untreated, thyroid cancer can significantly impact a patient’s quality of life. As the tumor grows, it may cause chronic pain in the neck area. This pain becomes more pronounced, especially when the tumor presses on surrounding tissues, and over time can make daily movements such as turning the head or swallowing more difficult. As the tumor continues to grow, the patient’s ability to speak can also be affected. Since the thyroid gland is located near the nerves that control the vocal cords, the tumor can press on these nerves and cause hoarseness.
As cancer progresses, pressure can also develop on the esophagus and trachea. This can lead to symptoms such as difficulty swallowing and shortness of breath, making basic activities like eating or sleeping more difficult. In advanced stages of thyroid cancer, a decline in general physical function may also be observed.
Other quality of life impacts due to thyroid cancer include:
- The cancer can cause persistent energy loss and a constant feeling of fatigue.
- Physical discomfort and difficulties in daily activities can negatively affect mental health.
- Pain and other symptoms may restrict the patient’s social life and lead to social isolation.
Is It Safe to Delay Treating Thyroid Cancer?
In some low-risk cases of thyroid cancer, treatment can be delayed, and this is considered safe with an active surveillance strategy. This method involves regular and close medical monitoring of small tumors that show no signs of spread. This approach, especially suitable for papillary thyroid cancers smaller than 1 cm, can help maintain the patient’s quality of life.
In cases where active surveillance is applied, ultrasound scans and clinical evaluations are usually conducted every 6–12 months. This ensures that tumor growth or the development of new risk factors is monitored. If the cancer shows signs such as growth of more than 3 mm or spread to lymph nodes, the treatment plan is reconsidered.
Some advantages of active surveillance include:
- Risk of damaging the vocal cords is reduced and lifelong hormone replacement therapy can be avoided.
- Many small cancers may remain stable over time and not require intervention.
- The risk of cancer progression is lower, especially in patients over 40 years old.
However, it should be emphasized that active surveillance is only a safe option for patients who are under constant medical supervision and meet specific criteria. This strategy may not be suitable for higher-risk cases with a tendency to progress rapidly. Therefore, candidates must be carefully selected and individualized decisions must be made.
Frequently Asked Questions
What stages does untreated thyroid cancer progress through?
Untreated thyroid cancer progresses through the following stages: Local Stage: Cancer is confined to the thyroid gland; 64% of cases are diagnosed at this stage and the 5-year survival rate is 99.9%. Regional Stage: Cancer has spread to nearby lymph nodes or tissues; 30% of cases are at this stage, with a 5-year survival rate of 98.2%. Distant Stage: Cancer has metastasized to distant organs such as the lungs or bones; this occurs in 3% of cases, with a 5-year survival rate of 51.9%. The progression rate of cancer varies depending on type and patient age; for example, anaplastic thyroid cancer progresses rapidly, while papillary thyroid cancer is slower. Early diagnosis and treatment are critical to prevent progression and increase survival.
What is the risk of thyroid cancer spreading to nearby tissues and organs?
The risk of thyroid cancer spreading to surrounding tissues and organs depends on its type and stage. Metastasis occurs in about 30% of patients, usually to regional lymph nodes, and in 1–4% of cases to distant organs such as the lungs and bones. The most common type, papillary thyroid cancer, has a 5-year survival rate of over 99% for local cases, but this drops to 74% with distant metastasis. The rare and highly aggressive anaplastic thyroid cancer has a 5-year survival rate of 39% for localized disease and only 4% for metastatic cases. Overall, the risk of spread to surrounding tissues and organs is low, and early diagnosis significantly improves outcomes.
How does untreated thyroid cancer affect quality of life?
Untreated thyroid cancer can severely affect quality of life; in addition to physical symptoms such as neck pain, difficulty swallowing, and breathing problems, it can also lead to psychological issues such as anxiety and depression. For papillary thyroid cancer, 5-year survival rates exceed 99.5% in local cases but drop to 74% with metastasis. For follicular thyroid cancer, these rates are over 99.5% in local cases and 67% for metastatic cases. In medullary thyroid cancer, the rate is over 99.5% for local cases, dropping to 43% with metastasis. For anaplastic thyroid cancer, the 5-year survival rate is 39% for localized disease and as low as 4% for metastatic disease. These data highlight the importance of early diagnosis and treatment in maintaining quality of life and improving survival rates.
Are treatment options more limited in late-stage disease?
Treatment options for thyroid cancer become more limited at advanced stages. In early-stage disease, thyroid cancer can often be effectively treated with surgical interventions such as total thyroidectomy or lobectomy, and radioactive iodine therapy if necessary. However, in advanced stages, especially when the cancer has metastasized or become resistant to radioactive iodine, treatment options are more restricted. For example, the rare and aggressive anaplastic thyroid cancer has limited treatment options and a poor prognosis. In these cases, systemic therapies (such as targeted therapies like kinase inhibitors) or participation in clinical trials may be considered, but these approaches generally show limited effectiveness. Therefore, early diagnosis and treatment are critical to expanding treatment options and improving outcomes for thyroid cancer patients.
Can untreated thyroid cancer be fatal?
Untreated thyroid cancer can be fatal, and mortality rates depend on the type and progression of the cancer. Globally, in 2019, thyroid cancer caused approximately 45,576 deaths, representing a 98% increase since 1990. In the United States, about 2,170 deaths from thyroid cancer are expected in 2024. The 5-year relative survival rate for thyroid cancer is 98.4%, but this rate drops significantly if not treated. For the rare and aggressive anaplastic thyroid cancer, the 5-year survival rate is only 4% in metastatic cases. Early diagnosis and treatment are vital for preventing fatal outcomes.
Interventional Radiology and Neuroradiology Speaclist Prof. Dr. Özgür Kılıçkesmez graduated from Cerrahpaşa Medical Faculty in 1997. He completed his specialization at Istanbul Education and Research Hospital. He received training in interventional radiology and oncology in London. He founded the interventional radiology department at Istanbul Çam and Sakura City Hospital and became a professor in 2020. He holds many international awards and certificates, has over 150 scientific publications, and has been cited more than 1500 times. He is currently working at Medicana Ataköy Hospital.
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