Papillary thyroid cancer or papillary thyroid carcinoma is the most common type of thyroid cancer, representing 75% to 85% of all cases of thyroid cancer. It happens more often in women and appears in the age group of 20-55 years. It is also the predominant type of cancer in children with thyroid cancer, and in patients with thyroid cancer who have had previous radiation to the head and neck. Often differentiated well, grow slowly, and localize, although it can metastasize.
Video Papillary thyroid cancer
Epidemiology
According to Supervision, Epidemiology and Outcome (SEER), the incidence of papillary cancer increased from 4.8 to 14.9 per 100,000 from 1975 to 2012. Women were more likely to develop papillary cancer compared with men with an incidence ratio of 2.5 to 1 most cancers are diagnosed between 40 and 50 years in women. However, the mortality rate from papillary cancer remains static from 2003 to 2012 of 0.5 per 100,000 men and women. There was an increased incidence of papillary cancer from 1910 to 1960 due to the use of ionizing radiation in treating head and neck cancer of childhood. Incidence decreased after radiation therapy was abandoned. Environmental exposure to radiation such as the Hiroshima and Nagasaki atomic bombs and the Chernobyl disaster also led to an increase in papillary thyroid cancer from 5 to 20 years after exposure to radiation. Family history of thyroid cancer syndrome such as familial adenomatous polyposis, Carney complex, Multiple endocrine neoplasia type 2 (MEN-2), Werner syndrome, and Cowden syndrome increase the risk of developing papillary cancer.
Maps Papillary thyroid cancer
Diagnosis
Papillary thyroid carcinoma is usually found on routine examination as an asymptomatic thyroid nodule that appears as a neck mass. In some cases, the mass may have produced localized symptoms. This mass is usually referred to as fine needle aspiration biopsy (FNA) for investigation. FNA accuracy is very high and this is a widely used process in these cases. Other investigative methods include ultrasound imaging and nuclear scanning. Ultrasound is a useful test to differentiate solids from cystic lesions and to identify calcification. Thyroid ultrasound is also very effective for finding microcarcinoma, which refers to a very small carcinoma (& lt; 1cm).
Papillary thyroid carcinomas are also found when hard nodules are found in multinodular goitre, when enlarged cervical lymph nodes are detected, or when there are unexplained metastatic lesions elsewhere in the body. Extending the lesions found in the thyroid gland, especially if they are painful, should be examined as they may indicate the existence of papillary thyroid carcinoma. Other clinical signs that may indicate papillary thyroid are fixation to the trachea, strong neck mass, recurrent laryngeal or recurrent laryngeal nerve damage. Five percent of the population can have thyroid nodules, and the majority will be benign.
Appropriate examination includes ultrasound of the neck, followed by laboratory examination. Patients will usually meet with an endocrinologist and surgeon (head and neck surgeon or endocrine surgeon).
Marker
Thyroglobulin can be used as a tumor marker for well-differentiated papillary thyroid cancer. HBME-1 staining may be useful for distinguishing papillary carcinoma with follicular carcinoma; in the papillary lesion tends to be positive.
Reducing ATP5E expression is significantly associated with the diagnosis of papillary thyroid cancer and may serve as an early tumor marker of the disease.
Pathology
Papillary thyroid cancer gets its name from the papillae among its cells, seen in microscopy. Features include:
- Characteristics of nuclear inclusion of Annie Orphan's eyes (a nucleus with uniform staining, which appears empty due to powder chromatin and marginal micronucleoli) and psammoma bodies in a light microscope. The first is useful in identifying follicular variants of papillary thyroid carcinoma.
- Lymphatic dissemination is more common than hematogenous spread
- Multifocality is common
- The so-called Lateral Aberrant Thyroid is actually a metastatic lymph node of papillary thyroid carcinoma.
- Papillary microcellemia is part of a papillary thyroid cancer defined as being less than or equal to 1 cm. The highest incidence of papillary thyroid microcarcinoma on autopsy has been reported by Harach et al. in 1985, which found 36 of 101 autopsies in succession to have incidental microcarcinoma. Michael Pakdaman et al. reported the highest incidence in a series of retrospective surgeries in 49.9 percent of 860 cases. Management strategies for incidental papillary microcarcinoma in ultrasound (and confirmed in FNAB) range from total thyroidectomy with radioactive iodine ablation for observation only. Harach et al. suggest using the term "paprika occult tumor" to avoid patients suffering from cancer. That's Woolner et al. who first arbitrarily coined the term "occult papillary carcinoma" in 1960, to describe papillary carcinoma <= 1.5 cm in diameter.
Some variants are recognized, although classic papillary thyroid carcinomas are the most common; microscopic, follicular variants, diffuse sclerosing variants, high cell variants, cell column variants, hobnail variants, among others. Encapsulated follicle variants, especially when not invasive, have been reclassified as non-invasive follicular thyroid neoplasms with papillary-like nuclear features.
Although papillary carcinoma has a tendency to attack the lymphatics, it is less likely to invade the blood vessels. These types of tumors are most often not encapsulated, and they have a high tendency to metastasize locally to lymph nodes, which can produce cystic structures near the thyroid that are difficult to diagnose due to malignant tissue deficiency. Furthermore, the papillary tumor may metastasize to the lungs and produce some nodules or lung fields can show the appearance of snowflakes throughout.
Another characteristic of papillary carcinoma is that E.M. showed increased mitochondria, increased RER, and increased apical microvilli. In addition, papillary carcinoma has sluggish growth, and 40 percent of cases spread from the capsule.
Related mutations
Mutations associated with papillary thyroid cancer are two forms of chromosomal translocation and one form of point mutation. This change leads to activation of a common carcinogenic pathway - the MAPK/ERK pathway.
A chromosome translocation involving RET proto-oncogene (encoding of tyrosine kinase receptors that play an important role in the development of neuroendocrine cells) located on the 10q11 chromosome occurs in about one-fifth of papillary thyroid cancers. The resulting combination of oncoprotein is called RET/PTC (ret/papillary thyroid carcinoma), and implicitly activates RET and downstream MAPK/ERK pathways. Frequency of ret/PTC translocation was significantly higher in papillary cancer that appeared in children and after radiation exposure. The NTRK1 gene (encoding the TrkA receptor), located on the 1q chromosome, is also transplanted in about 5 percent to 10 percent of papillary thyroid cancers.
About one-third to one-half of papillary thyroid carcinomas show point mutations on BRAF oncogens, also activating MAPK/ERK pathways. In those cases the BRAF mutation found was a V600E mutation. After performing a multivariate analysis, it was found that the absence of a tumor capsule was the only related parameter (P = 0.0005) with a BRAF V600E mutation. According to a recent study, papillary cancer that carries the common V600E mutation tends to have a more aggressive longer-term journey. BRAF mutations are common in papillary carcinoma and in differentiated cancers that have progressed from papillary tumors.
Prognosis
Depending on the source, the 5-year survival rate for papillary thyroid cancer is 96 percent or 97 percent, with a 10-year survival rate of 93 percent.
For a more specific prognosis for individual cases, there are at least 13 known assessment systems for prognosis; among the more commonly used are:
- AGE - Age, Class, Disease rate, Size
- AMES - Age, Metastasis, Disease rate, Size
- MACIS - Metastasis, Age at presentation, Completeness of surgical resection, Invasion (extrathyroidal), Size (this is a modification of AGE system). This is probably the most reliable staging method available. Also known as MAICS system.
- TNM staging - Tumors, nodes, metastases. The remarkable thing about staging TNM for thyroid (differentiated) carcinoma is that the scores differ by age.
MACIS
The MACIS system estimates the prognosis of papillary thyroid cancer developed by Clive S. Grant at the Mayo Clinic, and is based on careful evaluation of a large group of patients. This is probably the most reliable staging method available.
It gives a score on the major factors involved, and uses the sum of these scores to calculate the prognosis:
Most patients fall into the low risk category (MACIS score less than 6.0) and recover from cancer at the time of surgery.
Children with multiple pulmonary metastases and/or miliary aspects still have a good long-term prognosis if given adequate care.
Stage
Based on the overall stage of cancer being stage I to IV, papillary thyroid cancer has a 5-year survival rate of 100 percent for stages I and II, 93 percent for stage III and 51 percent for stage IV.
Treatment
Surgery remains the mainstay of treatment for papillary thyroid cancer. Revised American Thyroid Association 2009 guidelines for papillary thyroid cancer patients that initial procedures should be total-total or total thyroidectomy. Thyroid lobectomy alone may be sufficient to treat small, (low), unifocal, intrathyroidal, low-risk, unifocal, intrathyroidal carcinoma in the absence of previous head and neck irradiation or cervical or clinical metastatic cervical node involvement.
- Minimal disease (diameter up to 1.0 cm) - hemitiroidectomy (or unilateral lobectomy) and isthmectomy may be sufficient. There is some discussion as to whether this is still better than total thyroidectomy for this patient group.
- Gross disease (diameter greater than 1.0 cm) - Total thyroidectomy, and removal of central lymph nodes is the treatment of choice. Additional lateral neck nodes may be removed at the same time if ultrasound FNA imaging and TG thyroglobulin are positively guided at the ultrasound evaluation of the preoperative node.
The arguments for total thyroidectomy are:
- Reduce the risk of recurrence, if the central compartment node is removed on the original operation.
- 30-85% of papillary carcinoma is a multifocal disease. Hemithyroidectomy can leave diseases in other lobes. However, multifocal disease in the left lobe may not necessarily be clinically significant or serve as a detriment to patient survival.
- Ease of monitoring with thyroglobulin (sensitivity to recurrence increases with total thyroidectomy, and ablation of normal thyroid remnants by low-dose radioiodine 131 after following a low iodine diet (LID).
- Ease of detection of metastatic disease with ultrasound of the thyroid gland and neck.
- Postoperative complications in a high-volume thyroid surgery center with experienced surgeons comparable to hemyiroidectomy.
Arguments for hemithyroidectomy:
- Most patients have low-risk cancers with excellent prognosis, with similar survival outcomes in low-risk patients undergoing total thyroidectomy compared to hemitiroidectomy.
- Lack of possible patients who need lifetime thyroid replacement after surgery.
Thyroid body-wide examination is less reliable in finding recurrences of TG and ultrasound.
Papillary tumors tend to be more aggressive in patients over 45 years of age. In such cases, it may be necessary to perform a wider resection including part of the trachea. Also, the sternocleidomastoid muscle, the jugular vein, and the accessory nerve should be removed if the procedure allows for a seemingly complete resection of the tumor. If large numbers of residual tumors are left in the neck, external radiotherapy has been indicated and has proven to be particularly beneficial in cases when the remaining tumor does not take radioiodine.
After thyroid removal surgery, the patient waits for about 4-6 weeks to then have radioiodine therapy. This therapy is intended to detect and destroy all metastases and tissue residues in the thyroid. Treatment may be repeated 6-12 months after initial treatment of metastatic disease in which the disease recurs or has not been fully addressed.
Patients are given levothyroxine hormone replacement for life after surgery, especially after total thyroidectomy. Chemotherapy with cisplatin or doxorubicin has proven limited efficacy, however, it may be helpful for patients with bone metastasis to improve their quality of life. Patients are also prescribed levothyroxine and radioiodine after surgery. Levothyroxine affects tissue growth and maturation and is involved in normal growth, metabolism, and development. In the case of metastasis, patients are prescribed antineoplastic agents that inhibit cell growth and proliferation and help in relieving symptoms of progressive disease.
After successful treatment, 35 percent of patients may experience recurrence within a 40-year span. Also, patients may experience a high incidence of nodular metastases, with 35 percent of cases of cervical gland metastasis. About 20 percent of patients will develop several tumors in the thyroid gland.
There is ongoing discussion on the best management of optimal surgical procedures for papillary thyroid cancer. The prognosis of patients with papillary thyroid cancer is found to depend on patient age, tumor size, presence of metastatic disease, and tumor invasion into adjacent tissues near the thyroid gland. Recent studies have examined a more conservative approach to surgery and have demonstrated that hemyiroidectomy is acceptable for patients with low-risk papillary thyroid cancer with tumor size of 1 cm to 4 cm in the absence of invasion of tissue around the thyroid or metastasis. The study examining a large database of patients with papillary thyroid cancer concluded that there was no survival advantage for patients with stage I papillary thyroid with a size of 1-4 cm who received total thyroidectomy compared with hemithyroidectomy. Given this data, choosing an optimal course of surgical and medical management of papillary thyroid cancer should involve joint decision making of patients, endocrinologists, and surgeons.
References
External links
- Thyroid cancer in DMOZ
- Cancer Management Handbook: Thyroid and Parathyroid Cancer
- Management Guidelines for Patients with Thyroid Nodules and Thyroid Cancer Differentiation of the American Thyroid Association Task Force (2015).
- Statistics of thyroid cancer from Cancer Research UK
- International Thyroid Oncology Group (ITOG), a non-profit group dedicated to clinical trials to speed healing of thyroid cancer.
Source of the article : Wikipedia
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