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Radiation therapy is a powerful tool in the fight against cancer, particularly for cancer in the head, neck, and chest areas, including breast cancer. While this treatment saves lives, it can also affect healthy tissues near the cancer site—including your thyroid gland. When your thyroid is damaged by radiation, it may become unable to produce enough thyroid hormones, leading to a condition called hypothyroidism. Up to 50% of head, neck, chest, and breast cancer patients who receive radiation therapy develop an underactive thyroid, which can significantly impact their health and quality of life.
Recently, actor Stanley Tucci shared his experience of being diagnosed with hypothyroidism several years after radiation treatment for oral cancer. His story brings much-needed awareness to the connection between cancer treatment and thyroid dysfunction and left Tucci with a period of undiagnosed hypothyroidism. In this article, we’ll look at radiation-induced hypothyroidism, how to recognize it, and what treatment options are available.
Your thyroid is a butterfly-shaped gland located in the lower front part of your neck. Despite its small size, it plays a crucial role in regulating many bodily functions. The thyroid produces hormones that control metabolism—the process by which your body converts food into energy. These hormones affect virtually every organ and regulate essential functions, including heart rate, body temperature, digestion, and brain function.
When working properly, your thyroid maintains the proper hormone balance to keep your metabolism functioning appropriately. However, when damaged by radiation, the thyroid may not produce enough hormones, making you hypothyroid, which slows your metabolism and other bodily functions.
Radiation therapy uses high-energy beams to kill cancer cells. When treating head, neck, chest, and breast cancer, these beams often pass through or near the thyroid gland. While modern techniques aim to focus radiation precisely on cancer cells, nearby healthy tissues can still receive exposure.
The thyroid is particularly vulnerable to radiation damage. When radiation hits thyroid tissue, it damages cellular DNA and disrupts normal function. Thyroid gland volume can be reduced. Research shows that radiation-induced thyroid gland changes include the expression of certain enzymes in the thyroid (specifically DUOX1), which leads to increased production of reactive oxygen species (ROS). These ROS cause further damage to DNA and cellular structures, impairing the gland’s hormone-producing ability.
There are several types of cancer treated with radiation that are more likely to affect the thyroid and trigger thyroid disease. They include:
- Head and neck cancers: These encompass a wide range of malignancies in the oral cavity, pharynx, larynx, nasal cavity, paranasal sinuses, and salivary glands.
- Breast cancer: The thyroid is most at risk when radiation treatment for breast cancer targets the supraclavicular lymph nodes, which are located in the hollow above the clavicle (collarbone).
- Lymphomas: Particularly those affecting the neck region or requiring total body irradiation for stem cell transplantation.
- Leukemia: Especially in childhood cases where prophylactic cranial irradiation is used to prevent central nervous system relapses.
- Lung cancer: Treatment for cancers in the upper chest area may expose the thyroid to radiation.
- Esophageal cancer: Due to its proximity to the thyroid gland in the neck region.
Apart from the type of cancer, several other factors increase the risk of developing hypothyroidism after radiation therapy:
- Female gender (women appear more susceptible)
- Smaller thyroid volume before treatment
- Higher radiation doses to the thyroid
- Treatment with both surgery and radiation
- Specific radiation dosage parameters
Radiation dosage-related factors are particularly important. Research has identified specific parameters that can predict the likelihood of hypothyroidism after radiation therapy. For instance, research has shown that the mean dose to the thyroid and the percentage of thyroid volume receiving high doses of radiation significantly correlate with hypothyroidism risk. Recent research suggests that the volume of thyroid tissue spared from high doses of radiation may be the most robust predictor of subsequent thyroid function.
Research suggests that approximately 40 to 50% of patients who receive radiation to the neck area will develop hypothyroidism. Earlier studies reported lower rates, but improved screening practices and extended follow-up periods have revealed this higher incidence.
The timeline for developing hypothyroidism after radiation varies considerably. Some patients may show signs as early as three months after radiotherapy treatment, while for others, the adverse effects of thyroid problems may not appear until years after completion of therapy. This delayed onset makes regular monitoring essential, even for patients who initially show normal thyroid function after radiation treatment.
Hypothyroidism is a relatively common late effect of radiation treatment for breast cancer, particularly when radiation is directed to the supraclavicular region in the hollow above the collarbone. The incidence of hypothyroidism varies, and one large study found that after two years, the incidence of hypothyroidism increased by 6% in breast cancer patients receiving supraclavicular radiation compared to those who did not.
Another study found that the cumulative incidence of hypothyroidism increased from 8% three years after radiotherapy to 35% at five years. For patients who received radiation to the supraclavicular lymph nodes, the incidence rose from 10% to 40% at years three and five, respectively. A meta-analysis revealed that breast cancer survivors have a 48% higher risk of developing hypothyroidism compared to women without breast cancer. The risk was even higher for those receiving radiation to the supraclavicular region.
These findings suggest that hypothyroidism is a significant concern for patients with breast cancer who undergo radiation therapy, especially those who received treatment to the supraclavicular area. Regular monitoring of thyroid function is recommended for these patients to ensure timely detection and management of hypothyroidism.
When the thyroid doesn’t produce enough hormones, the body’s processes slow down. This can cause various symptoms that typically develop gradually over time. Common signs and symptoms of hypothyroidism include:
It’s important to note that initial symptoms can be subtle and easily attributed to other causes, particularly in cancer survivors who may be dealing with various treatment-related effects. Some patients may not notice any symptoms at all, so regular blood test monitoring is crucial.
The impact of hypothyroidism on quality of life can be significant. Beyond physical symptoms, hypothyroidism can lead to decreased general health perception, worse emotional well-being, cognitive impairment, and sexual dysfunction. Research has also shown that impaired thyroid function is associated with an increased overall risk of mortality, making proper diagnosis and treatment essential.
Recognizing these symptoms early and discussing them with a healthcare provider is crucial for timely diagnosis and treatment.
Stanley Tucci, the acclaimed actor and filmmaker, was diagnosed with oral cancer in 2017. He first revealed his diagnosis in his 2021 book, Taste: My Life Through Food. His treatment included high-dose radiation therapy and chemotherapy, which he described in an interview with the New York Times as “horrible.”
While grueling, Tucci’s treatment was successful and resulted in a remission from his cancer. In March of 2025, Tucci was a guest on an episode of David Tennant’s podcast, “David Tennant Does a Podcast With…” During the podcast, Tucci described debilitating changes in his energy levels that he noticed in 2024 while filming Searching For Italy, his popular food and travel series.
Said Tucci: “I would be so tired in the afternoon, like completely exhausted by one o’clock. I was like, ‘Something’s wrong with me.’ Finally, I had a blood test, and I was like, ‘I know something’s f—ing wrong with me.’ And my thyroid was non-functioning.”
Tucci explained that he is now taking synthetic thyroid hormone replacement, but he still doesn’t feel 100% back to normal. According to Tucci: “I still get tired in the afternoon. Literally, you can’t think, you can’t move…and once I started taking the pill, it made a huge difference…But I want to get back to where I was.”
Tucci’s experience with radiation-induced hypothyroidism points to a gap in doctor-patient communications. Given the risk of developing hypothyroidism, Tucci – and other patients undergoing radiation treatment for head, neck, chest, and breast cancer – should be fully briefed on the risks and symptoms of hypothyroidism after their radiation treatment and tested regularly afterward.
Diagnosing hypothyroidism after radiation involves blood tests that measure thyroid hormone levels. The most common tests include:
- Thyroid-stimulating hormone (TSH) is produced by the pituitary gland and signals the thyroid to produce hormones. When thyroid hormone levels are low, TSH levels rise as the body attempts to stimulate more thyroid hormone production. Elevated levels can indicate hypothyroidism.
- Free thyroxine (free T4) measures the available levels of one of the main hormones produced by the thyroid gland. Low levels can indicate hypothyroidism.
- Free triiodothyronine (free T3) measures available levels of the active thyroid hormone. Low levels of free T3 can indicate hypothyroidism.
Medical guidelines recommend checking thyroid function about three months after completing radiation therapy to the neck area. After this initial check, yearly testing is recommended for the rest of the patient’s life, as thyroid function can continue to decline over time. Paloma recommends more frequent testing if you have any symptoms that could indicate hypothyroidism.
Even patients who feel well should undergo regular testing, as hypothyroidism can develop without noticeable symptoms. Early identification and treatment of hypothyroidism can prevent more serious complications and improve the quality of life for cancer survivors.
The primary treatment for hypothyroidism is thyroid hormone replacement therapy. This medication replaces the missing thyroid hormone and restores normal metabolism and other bodily functions.
- Personalized medication: While many patients are started on levothyroxine – a synthetic form of the T4 (thyroxine) hormone, other patients do better with the addition of the T3 hormone in the form of liothyronine or natural desiccated thyroid (NDT), which combines natural forms of T4 and T3.
- Customized dosage is carefully determined based on several factors, including the patient’s weight, age, other medical conditions, and thyroid function test results.
- Consistent medication use is important, so follow recommended guidelines on how to take thyroid medication. Thyroid medication is usually taken once daily in the morning on an empty stomach, about 30-60 minutes before eating, to help optimize absorption.
- Dietary considerations: Avoiding excessive soy, iron supplements, and calcium within three to four hours of medication time can improve absorption.
- Monitoring and adjustments: Finding the optimal dose may take time and require regular testing, as well as periodic adjustments based on blood test results and symptom assessment.
- Regular follow-ups ensure the dosage remains effective and optimal.
For most people, thyroid hormone replacement therapy effectively manages hypothyroidism symptoms. Once the correct dosage is established, many patients report feeling much better, with improvements in energy, mental clarity, and overall well-being.
Managing hypothyroidism after radiation therapy becomes part of a cancer survivor’s ongoing health routine. While taking a daily pill may seem simple, there are several important considerations for effective management:
- Consistency is key: Take medication at the same time each day, ideally in the morning, on an empty stomach.
- Avoid interactions: Certain foods, supplements, and medications can interfere with levothyroxine absorption.
- Regular monitoring: Continue with recommended blood tests to ensure your medication dosage remains appropriate, as your needs may change over time.
- Be aware of symptoms: Learn to recognize signs that your medication may need adjustment, such as persistent fatigue, weight changes, or mood issues.
Beyond medication, lifestyle adjustments can support thyroid function and overall health:
Nutrition
A thyroid-friendly diet can help manage symptoms. Key nutrients include:
- Selenium (Brazil nuts, tuna) – helps regulate thyroid and immune function.
- Zinc (pumpkin seeds, beef) – supports hormone synthesis.
- Vitamin D (fatty fish, fortified dairy) – crucial for immune and metabolic health.
Exercise and metabolism support
Since hypothyroidism can slow metabolism, regular physical activity is important. Strength training and cardiovascular exercises can help maintain muscle mass and energy levels.
Stress management
Chronic stress impacts thyroid function. Mindfulness, meditation, and adequate sleep can help mitigate its effects.
Ongoing Medical Follow-Ups
Routine check-ups ensure that your thyroid function remains stable and that any necessary medication adjustments are made promptly.
While completely preventing radiation-induced hypothyroidism may not always be possible when radiation therapy is necessary for cancer treatment, certain approaches may help reduce the risk.
Modern radiation techniques such as Intensity-Modulated Radiation Therapy (IMRT) allow for more precise delivery of radiation to tumor sites while potentially sparing nearby healthy tissues like the thyroid. However, research comparing different radiation techniques has shown mixed results regarding thyroid protection. Some studies found no significant difference in hypothyroidism rates between 3D conformal radiation therapy and IMRT, while others showed some benefit with newer techniques.
Research has identified several ways to approach the dosing of radiation that may help reduce the risk and incidence of hypothyroidism. These include limiting the dose to the thyroid and ensuring that a sufficient volume of the thyroid gland is spared from high doses of radiation. Radiation oncologists can use these parameters when planning treatment to reduce thyroid damage while maintaining effective cancer treatment.
A few innovative approaches to preventing radiation-induced hypothyroidism are being explored. One such strategy involves surgically relocating the thyroid gland outside of the radiation field before beginning treatment. Small studies have shown that it is possible to transfer the thyroid from the neck to the forearm or thigh, with patients maintaining normal thyroid function after the procedure. However, this approach is still experimental and not widely available.
Hypothyroidism in patients treated with radiation therapy is a common but often overlooked consequence of cancer treatment. Stanley Tucci’s journey highlights the importance of long-term health monitoring for cancer survivors.
If you or a loved one has undergone radiation for head, neck, chest, or breast cancer, understanding the risk, recognizing the symptoms, and following through with regular monitoring are essential steps. Proactive thyroid screening, vigilant monitoring, and early intervention can prevent complications and improve your quality of life. By staying informed and working closely with healthcare providers, those affected can manage hypothyroidism effectively and maintain overall well-being.
Paloma Health provides a unique advantage for patients managing hypothyroidism. With access to clinicians trained specifically in thyroid health, convenient telehealth visits, and cutting-edge and convenient home test kits for thyroid function, Paloma ensures comprehensive care tailored to individual needs. Paloma’s integrated care platform combines medical expertise, lifestyle interventions, and nutritional support—all accessible from the comfort of home. This approach empowers patients with proactive health monitoring, including regular thyroid function tests.
While living with hypothyroidism requires ongoing medical attention and daily medication, advances in thyroid hormone replacement therapy continue to improve outcomes for patients. Paloma Health enhances this experience by offering seamless communication with healthcare providers through a mobile app, unlimited messaging with care coordinators, and same-day medication adjustments sent directly to your pharmacy. These features ensure that hypothyroid patients feel supported and in control of the care journey.
By partnering with Paloma Health, patients benefit from a personalized approach that improves quality of life and simplifies the management of hypothyroidism.
- Radiation therapy for head, neck, and chest cancers can damage the thyroid gland, potentially leading to hypothyroidism.
- Up to 50% of patients undergoing radiation in these regions develop thyroid dysfunction, manifesting as fatigue, weight gain, and cognitive issues.
- Specific risk factors include higher radiation doses, multimodal treatment (surgery plus radiation), and having a smaller thyroid volume.
- Early detection through routine thyroid function tests (TSH, free T4, and T3) is essential since symptoms can appear months or years post-treatment.
- Actor Stanley Tucci’s experience after cancer treatment underscores the real-life impact of radiation-induced hypothyroidism and the need for improved patient awareness.
- The standard treatment involves lifelong thyroid hormone replacement, with adjustments based on individual patient needs.
- Emerging approaches like IMRT and experimental thyroid relocation aim to reduce thyroid exposure, though complete prevention remains challenging.
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