Thyroid Cancer Causes And Risk Factors
Its not clear exactly what causes thyroid cancer to develop. However, there are a number of known potential risk factors, some of which can be modified and others that cant. According to the National Cancer Institute, risk factors for developing thyroid cancer include:
Other research led by Dr. Harari is looking at whether certain environmental exposures, including to pesticides and flame retardants, have a link to thyroid cancer.
The Potential Downside Of Finding More Thyroid Cancers
Like other cancers, thyroid cancer isnt one disease. There are several different types of thyroid cancer , and each type can have very different prognoses. For example, few people with anaplastic thyroid cancer, a very rare but aggressive type, will live for even a year. But almost everyone diagnosed with a small papillary thyroid cancer will be alive 5 years after diagnosis.
In fact, past autopsy studies have shown that many people die withnot froma small papillary thyroid cancer.
You can die with a cancer never knowing you had it, Dr. Davies said. If these cancers are found by chance, any intervention can potentially be overtreatmentthat is, therapy for a cancer that would have stayed the same or sometimes even gotten smaller, and never caused any symptoms.
And overtreatment not only carries the risk of side effects without any benefit to the patient, but it can also include substantial financial costs.
The most common side effect from surgery to remove part or all of the thyroid gland is a lifelong need for thyroid hormone replacement therapy, which can have its own side effects. Most people feel fine, but some might not feel as well as they did before surgery, Dr. Haymart said.
Surgery to remove thyroid cancer also has the potential to damage vocal cord functions or nearby glands that control calcium levels in the body, she explained.
Can I Prevent Thyroid Cancer
Many people develop thyroid cancer for no known reason, so prevention isnât really possible. But if you know youâre at risk for thyroid cancer, you may be able to take these steps:
- Preventive surgery: Genetic tests can determine if you carry an altered gene that increases your risk for medullary thyroid cancer or multiple endocrine neoplasia. If you have the faulty gene, you may opt to have preventive surgery to remove your thyroid gland before cancer develops.
- Potassium iodide: If youâve had radiation exposure during a nuclear disaster, such as the 2011 incident at Fukushima, Japan, taking potassium iodide within 24 hours of exposure can lower your risk of eventually getting thyroid cancer. Potassium iodide blocks your thyroid gland from absorbing too much radioiodine. As a result, your gland stays healthy.
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What Is Papillary Thyroid Cancer
Papillary thyroid cancer begins in the follicular cells in your thyroid that produce thyroglobulin . Its the most common type of thyroid cancer.
Your thyroid is a small, butterfly-shaped gland located at the front of your neck under your skin. Its a part of your endocrine system and controls many of your bodys important functions by producing and releasing certain hormones.
PTC tends to grow very slowly and usually develops in only one lobe of your thyroid gland.
There are several subtypes of papillary thyroid cancers. Of these, the follicular subtype is the most common. Other subtypes of papillary cancer arent as common and tend to grow and spread more quickly. They include:
Papillary thyroid cancer is also called papillary thyroid carcinoma.
Types Of Thyroid Cancer:
Papillary carcinoma:About 8 of 10 thyroid cancers are papillary carcinomas . Papillary carcinomas tend to grow very slowly and usually develop in only one lobe of the thyroid gland. Even though they grow slowly, papillary carcinomas often spread to the lymph nodes in the neck. Still, these cancers can often be treated successfully and are rarely fatal.
Follicular carcinoma:Follicular carcinoma, also called follicular cancer or follicular adenocarcinoma, is the next most common type, making up about 1 out of 10 thyroid cancers. It is more common in countries where people don’t get enough iodine in their diet. These cancers usually do not spread to lymph nodes, but they can spread to other parts of the body, such as the lungs or bones. The prognosis for follicular carcinoma is not quite as good as that of papillary carcinoma, although it is still very good in most cases.
Hürthle cell carcinoma:Also known as oxyphil cell carcinoma – is actually a variant of follicular carcinoma. It accounts for about 3% of thyroid cancers. The prognosis may not be as good as that of typical follicular carcinoma because this type is harder to find and treat. This is because it is less likely to absorb radioactive iodine, which is used both for treatment and to look for the spread of differentiated thyroid cancer.
Thyroid sarcoma:These rare cancers start in the supporting cells of the thyroid. They are often aggressive and hard to treat.
Continue to learn about thyroid cancer
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When To Get Medical Advice
See a GP if you have symptoms of thyroid cancer. The symptoms may be caused by less serious conditions, such as an enlarged thyroid , so it’s important to get them checked.
A GP will examine your neck and can organise a blood test to check how well your thyroid is working.
If they think you could have cancer or they’re not sure what’s causing your symptoms, you’ll be referred to a hospital specialist for more tests.
Find out more about how thyroid cancer is diagnosed.
Thyroid Cancer Survival Rates By Type And Stage
Survival rates can give you an idea of what percentage of people with the same type and stage of cancer are still alive a certain amount of time after they were diagnosed. They can’t tell you how long you will live, but they may help give you a better understanding of how likely it is that your treatment will be successful.
Keep in mind that survival rates are estimates and are often based on previous outcomes of large numbers of people who had a specific cancer, but they cant predict what will happen in any particular persons case. These statistics can be confusing and may lead you to have more questions. Your doctor is familiar with yoursituation ask how these numbers may apply to you.
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Does Medullary Thyroid Cancer Run In Families
Twenty-five percent of MTC cases run in families. MTC may be passed down when families carry a change in the RET gene that causes a condition called multiple endocrine neoplasia type 2, or MEN2. There are two types of MEN2: MEN2A and MEN2B.
MEN2A: If you have MEN2A, you have a high chance of getting MTC. You are also at risk for getting pheochromocytoma, a cancer of the adrenal glands. MEN2A is rare, affecting 1 in 40,000 people. MEN2A may also be called Sipple syndrome or PTC syndrome.
MEN2B: MEN2B can sometimes be passed from parent to child but most of the time, it isnt. If you have MEN2B, you have a 100% chance of getting MTC at a very young age. You also have a 50% chance of getting pheochromocytoma at some point in your life. MEN2B is also called WagenmannFroboese syndrome or MEN3.
What Are The Warning Signs Of Thyroid Cancer
You or your healthcare provider might feel a lump or growth in your neck called a thyroid nodule. Donât panic if you have a thyroid nodule. Most nodules are benign . Only about 3 out of 20 thyroid nodules turn out to be cancerous .
Other thyroid cancer symptoms include:
- Difficulty breathing or swallowing.
- Swollen lymph nodes in your neck.
What are the signs that thyroid cancer has spread?
If you have thyroid cancer that has spread to other areas of your body, you may experience symptoms such as:
- Exposure to radioactive fallout from nuclear weapons or a power plant accident.
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What Causes Papillary Thyroid Cancer
Scientists still dont know the exact cause of papillary thyroid cancer, but they have identified risk factors that increase your risk of developing PTC, including radiation exposure and certain genetic conditions.
Radiation exposure and papillary thyroid cancer
The rates of papillary thyroid cancer are higher in people who have a history of exposure to significant ionizing radiation. This exposure could be due to:
- High-dose external radiation treatments to your neck, especially during childhood, used to treat cancer or some noncancerous conditions.
- Radiation exposure from nuclear plant disasters. The Chernobyl nuclear accident in 1986 led to a 3- to 75-fold increase in PTC cases in fallout regions.
Genetics and papillary thyroid cancer
A few genetic conditions are associated with PTC, including:
Only 5% of all papillary thyroid cases are associated with these genetic conditions.
How Is Papillary Thyroid Cancer Diagnosed
Papillary thyroid cancer usually presents as a lump or nodule on your thyroid gland. You may notice it, or your healthcare provider may discover it during a routine neck examination. Sometimes, the nodule is discovered incidentally by imaging tests you get for other medical reasons.
Your healthcare provider will likely order the following tests to help diagnose PTC:
- Imaging tests: Your provider may order imaging tests to identify the nodule on your thyroid. These tests might include thyroid ultrasound, CT scan and/or magnetic resonance imaging .
- Fine needle aspiration : Your provider will likely want to take a small tissue sample, called a biopsy, from the nodule on your thyroid using a very thin needle. A pathologist will look at the tissue under a microscope to see if there are cancer cells and, if so, what type of thyroid cancer it is.
Your healthcare provider may also recommend genetic counseling to see if you have a genetic condition that may have caused PTC and may cause other types of tumors.
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Side Effects Of Thyroid Surgery
The risks of thyroid surgery include:
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Damage to the laryngeal nerve. It can be stunned, or one vocal cord wont move the same way as the other, Dr. Harari explains. About 5% of people temporarily experience this complication, and 1% have permanent damage. There are procedures to regain vocal strength, and an ENT specialist can assist the patient in these efforts.
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Hypoparathyroidism, or, as sometimes surgeons decide to remove one or more of the parathyroid glands four tiny glands that regulate the bodys calcium levels and are located near the back of the thyroid. People whose thyroid surgery involves a central neck incision have a 10% risk of parathyroid complications.
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Vagus nerve issues. Lateral neck incisions can risk impacting the vagus nerve, Dr. Harari says. This can have effects on the voice as well as the shoulder or tongue.
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Loss of thyroid function. After surgery, you will probably need to take pills for the rest of your life to replace lost thyroid hormones. If your parathyroid glands are also removed, you may also need to take calcium and vitamin D.
What Happens After A Thyroid Cancer Diagnosis
The disparity by sex in the prevalence of small papillary thyroid cancers found during life and after death suggests that many women are receiving treatment for small tumors that might never have caused symptoms, Dr. Davies explained.
The factors that lead more women to get a diagnosis of small papillary thyroid cancer are numerous and complex, she said. Women tend to be more likely than men to seek medical care overall. Theyre more likely to encounter health issues that may have hormonal causes, such as difficulties with pregnancy.
Thyroid ultrasound is widely used to evaluate medical problems that may involve the thyroid. But its not intended to be used to screen people who dont have symptoms for thyroid cancer, Dr. Davies explained. However, she added, it often gets ordered along with other tests to speed the process of diagnosing a potential thyroid issue.
That can lead to finding things that were unrelated to someones symptoms. And that can also distract from discovering the real cause of the problem someone came to the clinic for, said Dr. Davies.
The biggest challenge, said Dr. Haymart, is that its currently impossible to predict which tumors found by chance will pose a threat to health.
How do you determine which cancers might be indolent and just sit there for the rest of the patients life, and which ones might be aggressive and potentially cause harm? she asked. Thats very difficult to tease out.
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Study Population And Data Source
This retrospective cohort study was conducted using data from the Surveillance, Epidemiology, and End Results program, covering approximately 48.0% of the US population. Spanning over four decades, the SEER program routinely collects individual data on demographics, tumor morphology, stage at diagnosis, anatomic site, therapeutic modalities, and follow-up data for a range of cancer patients . In addition, due to its population-based program design, data from the SEER program can be used for comparisons with the general population, and thus are viable for estimating cancer incidence, mortality, and survival .
All thyroid cancer patients detected between 1975 and 2016 were retrieved from the SEER 18 database . Only patients with an index thyroid malignancy were included in this study. Patients whose diagnoses were extracted from their death certificates and whose follow-up information was incomplete were excluded . For comparison, we extracted age-, sex-, race-, and year-specific death data for the general US population between 1975 and 2016 .
Since the SEER is a publicly available database, access to the data required a signed research data agreement form. Institutional review board approval and the need for informed consent were waived for data obtained from the SEER database, as the study did not involve new experiments on human subjects and all data were anonymized.
Survival For All Types And Stages Of Thyroid Cancer
There are no UK-wide statistics available for thyroid cancer survival by stage. Survival statistics are available for each stage of thyroid cancer in England. These statistics are for people diagnosed between 2013 and 2017. There are some differences between men and women:
1 year survival
- 90 out of every 100 men survive thyroid cancer for at least 1 year after diagnosis
- More than 90 out of every 100 women survive thyroid cancer for at least 1 year after diagnosis
5 year survival
- Almost 85 out of every 100 men survive thyroid cancer for at least 5 years
- 90 out of every 100 women survive thyroid cancer for at least 5 years after diagnosis
10 year survival
- Around 85 out of every 100 people survive their cancer for 10 years or more after diagnosis
Cancer survival by stage at diagnosis for England, 2019Office for National Statistics
These figures are for net survival of people diagnosed between 2013 and 2017.
Net survival estimates the number of people who survive their cancer rather than calculating the number of people diagnosed with cancer who are still alive. In other words, it is the survival of cancer patients after taking into account that some people would have died from other causes if they had not had cancer.
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Whats The Thyroid Cancer Survival Rate
Eight out of 10 people who have thyroid cancer develop the papillary type. Papillary thyroid cancer has a five-year survival rate of almost 100% when the cancer is in their gland . Even when the cancer spreads , the survival rate is close to 80%. This rate means that, on average, youâre about 80% as likely to live for at least five years after diagnosis as someone who doesnât have metastatic papillary thyroid cancer.
Five-year survival rates for other thyroid cancer types include:
- Follicular: Close to 100% for localized around 63% for metastasized.
- Medullary: Close to 100% for localized around 40% for metastasized.
- Anaplastic: Close to 31% for localized 4% for metastasized.
Is thyroid cancer curable?
Yes, most thyroid cancers are curable with treatment, especially if the cancer cells havenât spread to distant parts of your body. If treatment doesnât fully cure thyroid cancer, your healthcare provider can design a treatment plan to destroy as much of the tumor as possible and prevent it from growing back or spreading.
Tumor Sites Associated With Fatal Conditions
The causes of death were also classified according to the sites of tumors mainly responsible for producing the fatal conditions in the total of 161 patients . Local lesions alone, including persistent or recurrent tumors in the thyroid or in the regional lymph nodes, were responsible for death in 35% of the patients in this series, distant metastatic lesions alone in 33%, and both local and metastatic lesions in 28%. In 4% of patients, tumor sites per se were not associated with fatal conditions death was attributed to complications related to chemotherapy or external irradiation. Distant metastatic lesions alone were responsible for deaths significantly more frequently in cases of differentiated carcinoma than in cases of anaplastic carcinoma.
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Clinical Characteristics Of The 161 Patients With Fatal Thyroid Carcinoma
The clinical characteristics of the 161 patients with fatal thyroid carcinoma are shown in . The female to male ratio for the total cases was 3.4 . Mean ages at initial treatment for total cases, anaplastic carcinomas, and differentiated carcinomas were 60.9, 65.8, and 58.7 yr, respectively mean ages at death were 66.4, 66.0, and 66.6 yr, respectively. Mean survival times from initial treatment to death were 67.8, 6.2, and 106.4 months, respectively. Mean age at initial treatment and mean survival with differentiated carcinoma differed significantly from mean age and mean survival with anaplastic carcinoma. One anaplastic carcinoma patient survived for an unusually long period of 4 yr. This patients papillary carcinoma had a very small metastatic focus within a lymph node that was resected.
It has been recognized that differentiated thyroid carcinoma can transform to anaplastic thyroid carcinoma . Ninety-nine patients in this series were diagnosed as having anaplastic carcinoma at the time of death. Thirty-seven of these patients were diagnosed with differentiated carcinoma at initial treatment, and in 17 of the patients diagnosed with anaplastic carcinoma at the time of death, differentiated carcinoma was histologically shown to exist as well. Based on radioiodine uptake status and histological findings , 35 of 79 of the differentiated carcinomas were considered poorly differentiated at initial treatment.