What is Papillary Thyroid Carcinoma?
Papillary thyroid carcinoma (PTC) is a type of cancer that develops from the skin-like cells in your thyroid, a small gland at the base of your neck that controls your metabolism. This cancer presents some unique features when viewed under a microscope. It’s the most common kind of thyroid cancer, but it also has a hopeful outlook overall.
PTC usually shows up as an uneven solid lump in the thyroid, but in rare instances, it can look more like a fluid-filled cyst. A key thing about this type of cancer is it’s often found spreading into tissues near the thyroid, such as the tiny vessels that carry lymph fluid (part of the body’s immune system). About 10% of people with PTC find out they have it because it’s spread to other parts of their bodies even at their first doctor’s appointment.
Despite this, the outlook is generally positive for most people with PTC, particularly for those who are under the age of 45.
What Causes Papillary Thyroid Carcinoma?
There are a few things that increase your chances of getting PTC, or papillary thyroid cancer:
1. Radiation Exposure: People who have been exposed to a lot of radiation in the past are more likely to get PTC.
2. Childhood Exposure: Back in the 1940s to 1960s, radiation therapy was used to treat certain diseases in children. This can increase the chances of these children developing PTC when they grow up. Normally, it takes about 10 years after exposure to radiation for a tumor to form, but sometimes it can take over 30 years.
3. Medical Therapy: Using high doses of radiation (more than 2000 cGy) to treat other life-threatening diseases can also increase the risk of PTC.
4. Environmental Exposure: The Chornobyl nuclear accident that happened on April 26, 1986, led to a massive increase in PTC cases in the fallout regions, especially among young children.
5. Genetics: Some hereditary health conditions can increase your risk of getting PTC. These include familial adenomatous polyposis—Gardner syndrome, Werner syndrome, and Carney complex type 1. About 5% of all PTC patients have a history of the disease in their family, and their cases tend to be more severe.
6. Other: Areas where people consume a lot of iodine in their diet have been found to have a higher rate of PTC. Also, individuals with a previously benign thyroid disease are more likely to develop PTC. There’s a trend showing that being overweight or obese might increase the chances of getting thyroid cancer. This trend was seen in a study that looked at how often people were diagnosed with thyroid cancer from 1995 to 2015.
Risk Factors and Frequency for Papillary Thyroid Carcinoma
Papillary Thyroid Cancer (PTC) is the most common type of thyroid cancer, making up around 80 to 85% of all thyroid cancer cases. Recent data shows an increase in the occurrence of PTC from 4.8 to 14.9 per 100,000 people from 1975 to 2012. However, it’s important to highlight that this increase might be due to overdiagnosing and not an actual rise in the disease. Overdiagnosis can happen as small microcancers are often accidentally found during routine imaging tests, leading to unnecessary treatment. Still, this treatment doesn’t necessarily change the outcome or mortality rate of the disease. The trend to over-treat is partly due to outdated aggressive surgical approaches, instead of the more recent conservative strategies involving observation or less invasive surgery. PTC is most common in middle-aged adults, particularly women, with a 3 to 1 female to male ratio. The average age of diagnosis is 50. Although rare in children, PTC is the leading pediatric thyroid cancer. It is also more common in white individuals than black individuals.
- PTC is the most common thyroid cancer type, accounting for around 80 to 85% of cases.
- There has been an increase in PTC cases over the past few decades, but this could be due to overdiagnosis.
- Overdiagnosis often happens when small microcancers are found by accident during routine imaging tests, leading to unnecessary treatment.
- The approach to treating thyroid cancer is changing with more emphasis on observation and less invasive surgery instead of aggressive surgery.
- PTC mainly affects middle-aged adults, with an average diagnosis age of 50.
- It is more common in women, with a 3 to 1 female to male ratio.
- Though rare in children, PTC is still the most common pediatric thyroid cancer.
- It is more common in white individuals than in black individuals.
Signs and Symptoms of Papillary Thyroid Carcinoma
Papillary thyroid cancer (PTC) often initially shows up as a painless lump in the thyroid, which is the gland at the base of the neck, sometimes with swollen lymph nodes nearby. About 20% of people with PTC notice a hoarse voice or difficulties swallowing due to nerve or trachea disruption. At the first medical examination, PTC is found to have spread to the lymph nodes in the neck in 27% of patients, usually from a tumor on the same side of the thyroid. A certain type of swelling in the lymph nodes may be rarely seen. Physical exam usually uncovers a hard, painless mass typically less than 5 centimeters in size. The lump often feels fixed in place and may have uneven edges.
Testing for Papillary Thyroid Carcinoma
When doctors suspect the presence of papillary thyroid cancer (PTC), they often turn to a procedure called a fine needle aspiration, or FNA. This is a common first step for diagnosing this type of cancer. In this procedure, a thin needle is used to draw out fluid and cells from the suspected tumor. The collected material will usually contain an abundance – or a high number – of cells. They may appear in different forms such as papillary structures, flat sheets, or 3D shapes. These are set against a background that could be watery or thick, like so-called ropy colloid, nuclear or calcific debris, macrophages (a type of immune cell), and fragments of connective tissue. The cancer cells themselves are larger than usual and can be long or oval-shaped. Their nucleus, or center, could also appear elongated and exhibit unusual characteristics.
Interestingly, thyroid function tests aren’t always helpful for diagnosing PTC, as most patients with PTC will have normal thyroid function. Therefore, these tests are usually of limited use.
To get a better look at the suspected cancer, doctors often use an imaging technique called ultrasound. PTCs usually show up as ‘cold’ (meaning, they are hypo-functioning or not functioning as they should) lumps on thyroid scans, but occasionally, they can appear as ‘hot’ (or hyperfunctioning) lumps. The ultrasound scan might show a lump that is hypoechoic (produces fewer echoes) or isoechoic (produces same level of echoes as surrounding tissue), solid, and with blurry edges. It might be taller-than-wide, have tiny areas of calcium deposits known as microcalcifications and exhibit a disordered blood vessel structure inside it. These ultrasound findings play a key role in guiding the fine needle aspiration procedure as well. Microcalcifications are a strong indicator of this type of cancer.
However, sometimes, other types of scans may be required to fully understand the extent and behavior of the tumor. These include CT scans, MRIs, and FDG-PET/CT scans, which could be useful for looking at whether the cancer has spread beyond the thyroid, to assess if it has grown into the chest area, to spot any recurrent tumors, and to improve the overall accuracy of the diagnosis.
Treatment Options for Papillary Thyroid Carcinoma
Your doctor will decide on the best treatment for you based on various factors, including the extent and location of the disease as revealed by tests like imaging and cytology. Recent guidelines suggest a more conservative approach to treating smaller papillary cancers. It is now common to watch and wait with these types of cancers, only opting for surgery if there are notable changes in the tumor’s size or other characteristics.
One surgical option, called a lobectomy, may be considered for single tumors that are smaller than 4 cm, with no signs of growth beyond the thyroid or spread to the lymph nodes. For larger tumors, or those that have spread beyond the thyroid or to the lymph nodes or other parts of the body, a total or near-total thyroidectomy (removal of all or nearly all of the thyroid) is usually recommended. However, in the case of smaller thyroid cancers that haven’t spread beyond the thyroid and with no signs of lymph nodes involvement, only a lobectomy is typically required unless there are reasons to remove the entire thyroid.
In some cases, a procedure known as prophylactic central-compartment neck dissection might be suggested. This involves the removal of lymph nodes in the neck even if they don’t appear to be involved in the disease. This precautionary measure can be useful for planning further treatment steps if required.
After thyroid surgery, radioiodine treatment is often utilized for patients with papillary thyroid cancer to eliminate any remaining normal thyroid tissue. This therapy is typically recommended several weeks after surgery. Radioiodine treatment is helpful in various scenarios, such as if the tumor is larger than 2 cm and there are additional risk factors, or if the tumor is smaller but has spread to distant parts of the body. However, it is important to note that radioiodine treatment may have side effects.
After a thyroidectomy, patients need to take lifelong thyroid hormone therapy, typically taking a hormone called levothyroxine. This medication needs to be at a high enough dose to suppress the production of thyrotropin, a hormone that can promote the growth of remaining thyroid cancer cells.
Other treatments like total thyroidectomy may also be suggested in specific circumstances, such as the presence of distant metastases, a history of radiation, spread of the cancer beyond the thyroid, the presence of tumors on both sides of the thyroid, the tumor being over 4 cm, poorly differentiated lesions, or positive cervical lymph nodes.
New techniques are being explored for treating small papillary thyroid cancers, such as thermal ablation and ultrasound radiofrequency ablation. Chemotherapy is usually reserved for patients with recurrent or inoperable disease after initial surgical treatment and radioactive iodine ablation. Some of the common agents used are kinase inhibitors that interfere with specific pathways in the body.
What else can Papillary Thyroid Carcinoma be?
When trying to diagnose PTC, which is a type of thyroid cancer, doctors need to also consider other conditions that might cause similar signs or changes in the body. These include:
- Reactive changes that occur after a needle biopsy, which can result in changes in the cell’s nucleus that appear similar to PTC.
- Severe chronic lymphocytic thyroiditis, which is a condition that results from inflammation, and can cause changes in the nucleus of cells that look like PTC.
- Nodules or lumps in the thyroid, also known as adenomatoid nodules.
- Diffuse hyperplasia, which is an increase in the number of normal cells in the thyroid.
- Dyshormonogenetic goiter, an enlarged thyroid gland due to a disorder in hormone production.
- Follicular adenoma, which is a benign or noncancerous growth in the thyroid.
- Follicular thyroid carcinoma, which is another type of thyroid cancer.
- Medullary thyroid carcinoma, yet another type of thyroid cancer.
- Metastatic tumors, which are tumors caused by cancer cells spreading from other parts of the body to the thyroid.
What to expect with Papillary Thyroid Carcinoma
Papillary thyroid cancer (PTC), often spreads to the nearby lymph nodes, yet it usually has a very good chance of successful treatment and recovery. However, there are some particular characteristics and features that may result in a less favorable outcome.
The likelihood of a less favorable prognosis is higher in papillary thyroid cancer cases when the following factors are present:
- Older age at diagnosis
- Large size of the tumor
- Growth of the cancer beyond the thyroid
- Being male
- Less well-formed or solid growth areas in the tumor, invasion into blood vessels, and abnormal number of chromosomes in the cells (aneuploidy)
- Specific PTC subtypes that are known to act more aggressively such as the tall cell variant, a diffuse sclerosis variant, the solid variant, and the follicular variant
Being aware of how these factors could affect prognosis is useful for patients, helping them understand their circumstances and manage expectations. Doctors consider these factors to tailor the right treatment plan for each patient.
Possible Complications When Diagnosed with Papillary Thyroid Carcinoma
Extra-thyroidal extension, which means the disease has spread beyond the thyroid, happens in about 8% to 32% of cases. On the other hand, local or regional recurrences, which means the disease comes back in the same area or closeby, occur in about 5% to 15% of people with PTC.
Distant metastasis, when the disease spreads far from the origin, happens in only 1% to 25% of cases. The most common locations for this are the lungs and bones. Though less common, it can also occur in the brain, liver, and skin.
Common Situations of The Disease:
- Extra-thyroidal extension: Occurs in about 8% to 32% of cases
- Local or regional recurrences: Occurs in 5% to 15% of people with PTC
- Distant metastasis: Happens in 1% to 25% of cases, mainly in lungs and bones, and less commonly, the brain, liver, and skin.
Recovery from Papillary Thyroid Carcinoma
Long-term check-ups every 6 to 12 months for at least 5 years, and yearly after that, are important to check if the condition comes back. During these visits, medical professionals will check levels of TSH (a thyroid-stimulating hormone), Thyroglobulin (a protein produced by the thyroid gland), and antithyroglobulin antibodies (proteins that the immune system produces to fight against thyroglobulin) in your blood.
Preventing Papillary Thyroid Carcinoma
It’s important for patients to understand the size and spread of their thyroid cancer, and what the next steps are in terms of check-ups and further treatment. Doctors should let patients know that the long-term outlook for this type of cancer is generally good. This can help reduce patients’ anxiety and help prevent them from feeling stigmatized by their diagnosis.