Thyroid Causes, Diagnosis, Surgery - Thyroid Cancer Specialist Dr. Nikhilesh Borkar
* The thyroid gland is a butterfly-shaped endocrine gland that is normally located in the lower front of the neck.
* The thyroid’s job is to make thyroid hormones, which are secreted into the blood and then carried to every tissue in the body.
* Thyroid hormone helps the body use energy, stay warm and keep the brain, heart, muscles, and other organs working as they should.
* Solid or fluid-filled lumps that form within your thyroid.
* You often won't know you have a thyroid nodule until your doctor discovers it during a routine medical exam.
* Some thyroid nodules, however, may become large enough to be visible or make it difficult to swallow or breathe.
* Treatment options depend on the type of thyroid nodule you have.
* Closer to 30% of adult women have nodules detectable by ultrasound. In fact, diagnosis of a thyroid nodule is the most common endocrine problem.
* Although the majority of thyroid nodules are benign (not cancerous), about 10% of nodules do contain cancer.
* Any unusual swelling in your neck, especially if you have trouble breathing or swallowing. It's important to evaluate the possibility of cancer.
* If you develop signs and symptoms of hyperthyroidism, such as:
> Sudden weight loss even though your appetite is normal or has increased
> A pounding heart
> Trouble sleeping
> Muscle weakness
> Nervousness or irritability
Iodine deficiency. Lack of iodine in your diet can sometimes cause your thyroid gland to develop thyroid nodules. But iodine deficiency is uncommon in countries, where iodine is routinely added to table salt and other foods.
Overgrowth of normal thyroid tissue. Why this occurs isn't clear, but such a growth — which is sometimes referred to as a thyroid adenoma — is noncancerous and isn't considered serious unless it causes bothersome symptoms from its size. Some thyroid adenomas (autonomous or hyperfunctioning thyroid nodules) produce thyroid hormones outside of your pituitary gland's normal regulatory influence, leading to an overproduction of thyroid hormones (hyperthyroidism).
Thyroid cyst. Fluid-filled cavities (cysts) in the thyroid most commonly result from degenerating thyroid adenomas. Often, solid components are mixed with fluid in thyroid cysts. Cysts are usually benign, but they occasionally contain malignant solid components.
Chronic inflammation of the thyroid (thyroiditis). Hashimoto's disease, a thyroid disorder, can cause thyroid inflammation resulting in nodular enlargement. This often is associated with reduced thyroid gland activity (hypothyroidism).
Multinodular goiter. "Goiter" is a term used to describe any enlargement of the thyroid gland, which can be caused by iodine deficiency or a thyroid disorder. A multinodular goiter contains multiple distinct nodules within the goiter.
Thyroid cancer. Although the chances that a nodule is malignant are small, certain factors increase your risk of thyroid cancer, such as a family history of thyroid or other endocrine cancers. Other risk factors include being younger than 30 or older than 60, being a male, or having a history of radiation exposure, particularly to the head and neck. A nodule that is large and hard or causes pain or discomfort is more worrisome in terms of malignancy.
Problems swallowing or breathing. Large nodules or a multinodular goiter — an enlargement of the thyroid gland containing several distinct nodules — can interfere with swallowing or breathing.
Hyperthyroidism. Problems can occur when a nodule or goiter produces thyroid hormone, leading to hyperthyroidism. Hyperthyroidism can result in weight loss, muscle weakness, heat intolerance, and anxiousness or irritability.
Potential complications of hyperthyroidism include an irregular heartbeat (atrial fibrillation); weak bones (osteoporosis); and thyrotoxic crisis, a sudden and potentially life-threatening intensification of signs and symptoms that requires immediate medical care.
Problems associated with thyroid cancer. If a thyroid nodule is cancerous, surgery is usually required. Generally, most or all of your thyroid gland is removed, after which you'll need to take thyroid hormone replacement therapy for the rest of your life.
The main goals is to rule out the possibility of cancer. We also want to know if your thyroid is functioning properly.
Physical exam. You'll be asked to swallow while we examine your thyroid because the nodule with your thyroid gland will usually move up and down during swallowing.
We look for signs and symptoms of hyperthyroidism, such as tremor, overly active reflexes, and a rapid or irregular heartbeat; and signs and symptoms of hypothyroidism, such as a slow heartbeat, dry skin and facial swelling.
Thyroid function tests. Tests that measure blood levels of thyroxine(T4) and triiodothyronine(T3), hormones produced by your thyroid gland, and thyroid-stimulating hormone (TSH), which is released by your pituitary gland, can indicate whether your thyroid is producing too much thyroxine (hyperthyroidism) or too little (hypothyroidism).
Ultrasonography. This imaging technique uses high-frequency sound waves rather than radiation to produce images. It provides the best information about the shape and structure of nodules. It may be used to distinguish cysts from solid nodules or to determine if multiple nodules are present. It may also be used as a guide in performing a fine-needle aspiration biopsy.
Fine-needle aspiration (FNA) biopsy. Nodules are often biopsied to make sure no cancer is present. FNA biopsy helps to distinguish between benign and malignant thyroid nodules. During the procedure, we insert a very thin needle in the nodule and removes a sample of cells.
The procedure, which is carried out in the clinic, takes about 20 minutes and has few risks. Often, we use ultrasound to help guide the placement of the needle. The samples are then sent to the laboratory and analysed under a microscope.
1. The nodule is benign (noncancerous).
This result is obtained in up to 80% of biopsies. The risk of overlooking a cancer when the biopsy is benign is generally less than 3 in 100 tests or 3%. This is even lower when the biopsy is reviewed by an experienced pathologist at a major medical center. Generally, benign thyroid nodules do not need to be removed unless they are causing symptoms like choking or difficulty swallowing. Follow up ultrasound exams are important. Occasionally, another biopsy may be required in the future, especially if the nodule grows over time.
2. The nodule is malignant (cancerous) or suspicious for malignancy.
A malignant result is obtained in about 5% of biopsies and is most often due to papillary cancer, which is the most common type of thyroid cancer. A suspicious biopsy has a 50-75% risk of cancer in the nodule. These diagnoses require surgical removal of the thyroid after consultation with your endocrinologist and surgeon.
3. The nodule is indeterminate.
This is actually a group of several diagnoses that may occur in up to 20% of cases. An Indeterminate finding means that even though an adequate number of cells was removed during the fine needle biopsy, examination with a microscope cannot reliably classify the result as benign or cancer.
> The biopsy may be indeterminate because the nodule is described as a Follicular Lesion. These nodules are cancerous 20-30% of the time. However, the diagnosis can only be made by surgery. Since the odds that the nodule is not a cancer are much better here (70-80%), only the side of the thyroid with the nodule is usually removed. If a cancer is found, the remaining thyroid gland usually must be removed as well. If the surgery confirms that no cancer is present, no additional surgery to “complete” the thyroidectomy is necessary.
> The biopsy may also be indeterminate because the cells from the nodule have features that cannot be placed in one of the other diagnostic categories. This diagnosis is called atypia, or a follicular lesion of undetermined significance. Diagnoses in this category will contain cancer rarely, so repeat evaluation with FNA or surgical biopsy to remove half of the thyroid containing the nodule is usually recommended.
4. The biopsy may also be nondiagnostic or inadequate.
This result is obtained in less than 5% of cases when an ultrasound is used to guide the FNA. This result indicates that not enough cells were obtained to make a diagnosis but is a common result if the nodule is a cyst. These nodules may require reevaluation with second fine needle biopsy, or may need to be removed surgically depending on the clinical judgment of your doctor.
New tests that examine the genes in the DNA of thyroid nodules are currently available and more are being developed.
These tests can provide helpful information about whether cancer may be present or absent. These tests are particularly helpful when the specimen evaluated by the pathologist is indeterminate.
These specialized tests are done on samples obtained during the normal biopsy process.
There are also specialized blood tests that can assist in the evaluation of thyroid nodules.
These are currently available only at highly specialized medical centers, however, their availability is increasing rapidly.
Thyroid scan. In some cases, your doctor may recommend a thyroid scan to help evaluate thyroid nodules. During this test, an isotope of radioactive iodine is injected into a vein in your arm. You then lie on a table while a special camera produces an image of your thyroid on a computer screen.
Nodules that produce excess thyroid hormone — called hot nodules — show up on the scan because they take up more of the isotope than normal thyroid tissue does.
Cold nodules are nonfunctioning and appear as defects or holes in the scan. Hot nodules are almost always noncancerous, but a few cold nodules are cancerous. The disadvantage of a thyroid scan is that it can't distinguish between benign and malignant cold nodules.
The length of a thyroid scan varies, depending on how long it takes the isotope to reach your thyroid gland. You may have some neck discomfort because your neck is stretched back during the scan, and you'll be exposed to a small amount of radiation.
The most common thyroid cancer is papillary (85%) with cure rates of almost 99% for early stage & 90% overall.
Follicular is second most common (10-12%) with again high cure rates.
Medullary is third most common (3%), but the cure rates are not as high as the other two. 10-20 % are familial.
Anaplastic cancer is a rare but one of the worst cancers to have due to rapid growth & spread.
surgery for thyroid may be:
Hemithyroidectomy or Total thyroidectomy depending on the size of the tumor and on whether or not the tumor is confined to the thyroid.
For very small cancers (<1 cm) that are confined to the thyroid, involving only one lobe and without evidence of lymph node involvement a simple hemithyroidectomy (removal of only the involved lobe) is considered sufficient.
Spread of the tumor into surrounding areas or the presence of obviously involved lymph nodes – will indicate that a total thyroidectomy is a better option.
If thyroid cancer present in the lymph nodes of the neck, they will be removed at the time of the initial thyroid surgery or sometimes, as a later procedure if lymph node metastases become evident later on.
Recent studies even suggest that small tumors – called micro papillary thyroid cancers – may be observed without surgery depending on their location in the thyroid.
After surgery, most patients need to be on thyroid hormone for the rest of their life.
Often, thyroid cancer is cured by surgery alone, especially if the cancer is small. If the cancer is larger, if it has spread to lymph nodes or if your doctor feels that you are at high risk for recurrent cancer, radioactive iodine may be used after the thyroid gland is removed.
Thyroid cells and most differentiated thyroid cancers absorb and concentrate iodine. That is why radioactive iodine can be used to eliminate all remaining normal thyroid tissue and potentially destroy residual cancerous thyroid tissue after thyroidectomy.
Since most other tissues in the body do not efficiently absorb or concentrate iodine, radioactive iodine used during the ablation procedure usually has little or no effect on tissues outside of the thyroid.
However, in some patients who receive larger doses of radioactive iodine for treatment of thyroid cancer metastases, radioactive iodine can affect the glands that produce saliva and result in dry mouth complications.
If higher doses of radioactive iodine are necessary, there may also be a small risk of developing other cancers later in life. This risk is very small, and increases as the dose of radioactive iodine increases.
The potential risks of treatment can be minimized by using the smallest dose possible. Balancing potential risks against the benefits of radioactive iodine therapy is an important discussion that you should have with your doctor if radioactive iodine therapy is recommended.
Your TSH will need to be elevated prior to the treatment. This can be done in one of two ways.
> The first is by stopping thyroid hormone pills for 3-6 weeks. This results in hypothyroidism, which may involve symptoms such as fatigue, cold intolerance and others, that can be significant. To minimize the symptoms of hypothyroidism your doctor may prescribe T3, which is a short acting form of thyroid hormone that is usually taken after the levothyroxine is stopped until the final 2 weeks before the radioactive iodine treatment.
> Second is by using Recombinant human TSH
Low iodine diet for 1 to 2 weeks prior to treatment.
For more advanced cancers, or when radioactive iodine therapy is no longer effective, other forms of treatment are needed.
New chemotherapy agents.
Periodic follow-up examinations as the thyroid cancer can return—sometimes several years after successful initial treatment.
History and physical examination.
Thyroglobulin - low levels post total thyroidectomy, but Antithyroglobulin antibodies (TgAb) make Tg undetectable, which can make it difficult to rely on the Tg result, as this may be inaccurate.
TSH - More advanced cancers usually require higher doses of levothyroxine to suppress TSH (if high risk cancer).
In cases of minimal or very low risk cancers, TSH is kept in the normal range.
In addition to routine blood tests, your doctor may want to repeat a whole-body iodine scan to determine if any thyroid cells remain. Increasingly, these scans are only done for high risk patients and have been largely replaced by routine neck ultrasound and thyroglobulin measurements that are more accurate to detect cancer recurrence, especially when done together.
PET CT scan if Thyroglobulin elevated & negative Iodine scan.
Thyroid nodules generally do not cause symptoms.
Thyroid tests are most typically normal—even when cancer is present in a nodule.
The best way to find a thyroid nodule is to make sure your doctor checks your neck!
Overall, the prognosis of differentiated thyroid cancer is excellent.
For patients older than 45 years of age, or those with larger or more aggressive tumors, the prognosis remains very good, but the risk of cancer recurrence is higher.
Advanced cancers and if they cannot be completely removed with surgery or destroyed with radioactive iodine treatment prognosis is not so good, but nonetheless, these patients often are able to live a long time and feel well, despite the fact that they continue to live with cancer.