2. introduction
• Cancer is a group of many related diseases. All cancers begin in cells,
the body's basic unit of life. Cells make up tissues, and tissues make
up the organs of the body.
• Normally, cells grow and divide to form new cells as the body needs
them. When cells grow old and die, new cells take their place.
• Sometimes this orderly process goes wrong. New cells form when the
body does not need them, and old cells do not die when they should.
These extra cells can form a mass of tissue called a growth or tumor.
• Growths on the thyroid are usually called nodules.
3. Thyroid nodules can be benign or malignant:
• Benign nodules are not cancer.
• Cells from benign nodules do not spread to other parts of the body.
• They are usually not a threat to life.
• Most thyroid nodules (more than 90 percent) are benign.
• Malignant nodules are cancer.
• They are generally more serious and may sometimes be life threatening.
• Cancer cells can invade and damage nearby tissues and organs.
• Also, cancer cells can break away from a malignant nodule and enter the
bloodstream or the lymphatic system.
• That is how cancer spreads from the original cancer (primary tumor) to form new
tumors in other organs. The spread of cancer is called metastasis.
4. Benign thyroid tumors
Follicular Adenoma
• Present clinically as solitary nodule, may secret thyroid hormones.
The distinction between a follicular adenoma & carcinoma must be
based on histological examination, FNAC is not sufficient as the
difference between them is in the invasion of pericapsular blood
vessels & the capsule of the gland.
Papillary adenoma
• Actually does not even exist and any papillary architecture should be
considered as papillary carcinoma and hence treated as such.
6. Malignant tumors of the thyroid
• Frequency of thyroid Ca is approximately 1% of all
malignancies.
• The incidence of cancer of the thyroid gland varies between
populations from 0.5% to 10% worldwide.
• Thyroid cancer is the commonest (90%) of all endocrine
malignancy with the highest contribution to endocrine
related cancer death.
• Thyroid cancer comprises of heterogeneous tumors with
variable biological behavior.
7. • The risk and frequency thyroid cancer increases with
age, and female to male ratio is 2.5:1.
• Majority of these tumors present as a thyroid mass or
nodular goiter.
• Therefore a thyroid nodule may be malignant and the
risk of malignancy varies depending on the type or
characteristic of the nodule.
• Secondary tumors are usually blood borne from
cancer of breast, colon & kidneys.
8. The following are the major types of thyroid
cancer:
• Papillary and follicular thyroid cancers account for 80 to 90 percent of all
thyroid cancers. Both types begin in the follicular cells of the thyroid. Most
papillary and follicular thyroid cancers tend to grow slowly. If they are
detected early, most can be treated successfully.
• Medullary thyroid cancer accounts for 5 to 10 percent of thyroid cancer
cases. It arises in C cells, not follicular cells. Medullary thyroid cancer is
easier to control if it is found and treated before it spreads to other parts of
the body.
• Anaplastic thyroid cancer is the least common type of thyroid cancer (only
1 to 2 percent of cases). It arises in the follicular cells. The cancer cells are
highly abnormal and difficult to recognize. This type of cancer is usually
very hard to control because the cancer cells tend to grow and spread very
quickly.
9. • If thyroid cancer spreads (metastasizes) outside the thyroid, cancer
cells are often found in nearby lymph nodes, nerves, or blood vessels.
• If the cancer has reached these lymph nodes, cancer cells may have
also spread to other lymph nodes or to other organs, such as the
lungs or bones.
• When cancer spreads from its original place to another part of the
body, the new tumor has the same kind of abnormal cells and the
same name as the primary tumor.
• For example, if thyroid cancer spreads to the lungs, the cancer cells in
the lungs are thyroid cancer cells. The disease is metastatic thyroid
cancer, not lung cancer. It is treated as thyroid cancer, not as lung
cancer
10. Papillary carcinoma of the thyroid gland
• The Incidence of papillary carcinoma of the thyroid is 3.7 per 100.000
of the population, and Female to male ratio is 2.5:1.
• The major predisposing factor is external irradiation to the neck in
childhood.
• They accounts for about 80% of thyroid cancers in childhood and 60%
in adults.
• They are slow growing and uncapsulated tumors.
• Tumor is histologically characterized by papillary projections with pale
empty nucleus (Opharn Annie – eyed nuclei) and calcified bodies
called psammoma bodies.
11. • The tumor have variable size and are usually multifocal
(multiple foci in the same lobe) about 20-80% and bilateral in
about one third of cases.
• These tumors have tendency to lymphatic involvement
within the thyroid and to regional lymph nodes in 80%,
however only 35% will be detectable clinically.
• The good thing about papillary carcinoma is that survival is
not adversely affected by lymphatic spread and therefore
they have good prognosis when compared to the rest of
thyroid cancers with mortality of about 11%.
12.
13. Occult carcinoma
•The term occult carcinoma describes small
probably clinically undetectable papillary tumors
usually less than 1.5cm in diameter which has
involved and caused enlargement of cervical
lymph node which in turn is clinically detectable.
•They have excellent prognosis.
14. Follicular carcinoma of the thyroid
• Endemic nodular goiter due to prolonged TSH stimulation
predisposes to Follicular carcinoma.
• These tumors accounts for about 20% of all thyroid cancers and
are common in iodine deficiency regions.
• They are TSH dependant and tend to be slow growing, unifocal
and capsulated.
• It is the invasion of the capsule and pericapsular vessels which
demonstrates malignancy in these tumors.
15. • Follicular carcinoma have tendency to hematogenous
metastasis to involve lungs, bones and kidney and
hence poorer prognosis when compared to papillary
type.
• They do not have tendency to multicentricity and
lymph node involvement are rare.
• Hürthle-cell carcinoma is a cytological variant with
Hurthle (oxyphil cells); it is associated with poor
prognosis.
16.
17. Medullary carcinoma of the thyroid gland
• Originates in parafollicular (C cells), this tumor produces calcitonin,
but it can also secret other hormones such as corticotropin,
serotonin, melanin and prostaglandins leading to paraneoplastic
syndrome.
• Because the tumor doesn’t arise from thyroid cells, it is TSH
independent.
• The incidence is about of 6% of all thyroid cancers.
• Medullary carcinoma may be familial (25%) which affects children and
young or sporadic (75%) which occurs at any age and sex.
18. • The tumor is usually unilateral and involves both regional
lymph nodes in about 50% of patients and hematogenous
metastases to the liver, lung, bone, and brain is common.
• The overall survival of patients with medullary carcinoma is
65% at 10 years, and the poor prognostic factors include
• advanced age,
• advanced stage,
• prior neck surgery,
• associated-MEN.
19.
20. Anaplastic carcinoma of the thyroid gland
• This is a poorly differentiated tumor.
• The incidence of anaplastic carcinoma of the thyroid is 13%,
• it is a disease of old and female to male ratio is 1:1.5.
• Microscopically it is composed of Spindle cell either small or large cell type.
• It is an aggressive tumor with extrathyroidal extension and tends to spread
by direct infiltration to adjacent structures leading to tracheal obstruction,
perforation, recurrent laryngeal nerve infiltration with hoarseness, or
esophageal obstruction.
• It can also spread through regional lymphatics or blood spread.
• It has the poorest prognosis of all thyroid cancers.
• Most patients die within 1 to 2 years.
21. Lymphoma of the thyroid gland
• It a rare entity of the thyroid cancer, usually follows
autoimmune Hashimoto’s thyroiditis.
• It more common in females and tend occur in adulthood (60
years) and of Non Hodgkin type.
• Thyroid lymphoma may be associated with hypothyroidism
in 30-40%.
• It grows fast, however the prognosis is favorable because it is
usually confined to the thyroid which is accessible to
chemotherapy and radiation
22. Investigations in thyroid neoplasia
• Thyroid function test will exclude hyperthyroidism.
• Fine Needle Aspiration Cytology (FNAC) is essential to
establish malignancy. It is should always be done in thyroid
neoplasia.
• Lobectomy and histological examination
• Lobectomy is the surgical removal one lobe of the thyroid
gland, usually with ithsmusectomy. This should be done to all
nodules with follicular pattern on FNAC.
23. • Thyroid scan
• This is done in cases with intermediate cytological results. Cold nodules are
likely to be malignant, while hot nodules have very little likelihood of being
malignant.
• Chest X –rays
• The chest X-ray is very important to rule out retrosternal extension and
lung metastasis. On the other hand thoracic inlet X-rays are necessary to
establish tracheal compression and deviation.
• Bone X-rays and bone scan
• These two investigatations should be requested when bone metastasis is
suspected. This will establish bone metastasis especially follicular and
medullary carcinoma of the thyroid. The former tend to cause osteolytic
lesion and the later tend to form osteoblastic lesion on bone X-rays. Bone
metastases are usually hot on bone scan.
24. • Abdominal ultrasound
• Abdominal ultrasound is an important investigation to exclude liver
metastasis.
• Computed Tomography scan
• CT scan of the neck, chest and abdomen can also establish the extent
of the tumor, especially in large tumors. In this way the nature of
surgical intervention can be contemplated.
• Indirect Laryngoscopy
• Indirect laryngoscopy is an important investigation. It is advised in
patient with hoarse voice to establish base line findings.
25. Causes and risk factors
• No one knows the exact causes of thyroid cancer
• Research has shown that people with certain risk
factors are more likely than others to develop thyroid
cancer
• The following risk factors are associated with an
increased chance of developing thyroid cancer:
26. Radiation.
• People exposed to high levels of radiation are much more likely than
others to develop papillary or follicular thyroid cancer.
• One important source of radiation exposure is treatment with x-rays.
• Another source of radiation is radioactive fallout. This includes fallout
from atomic weapons testing, nuclear power plant accidents and
releases from atomic weapons production plants.
• Such radioactive fallout contains radioactive iodine (I-131). People,
who were exposed to one or more sources of I-131, especially if they
were children at the time of their exposure, may have an increased
risk for thyroid diseases
27. Family history.
• Medullary thyroid cancer can be caused by a change, or alteration, in
a gene called RET. The altered RET gene can be passed from parent to
child. Nearly everyone with the altered RET gene will develop
medullary thyroid cancer.
• A blood test can detect an altered RET gene. If the abnormal gene is
found in a person with medullary thyroid cancer, the doctor may
suggest that family members be tested. For those found to carry the
altered RET gene, the doctor may recommend frequent lab tests or
surgery to remove the thyroid before cancer develops.
• A small number of people with a family history of goiter or certain
precancerous polyps in the colon are at risk for developing papillary
thyroid cancer.
28. Being female.
• Women are two to three times more likely than men to
develop thyroid cancer.
Age.
• Most patients with thyroid cancer are more than 40 years
old. People with anaplastic thyroid cancer are usually more
than 65 years old.
Race.
• White people are more likely than African Americans to be
diagnosed with thyroid cancer.
29. Not enough iodine in the diet.
•The thyroid needs iodine to make thyroid
hormone.
•In the United States, iodine is added to salt to
protect people from thyroid problems. Thyroid
cancer seems to be less common in the United
States than in countries where iodine is not part
of the diet.
30. Symptoms of thyroid cancer
• Early thyroid cancer often does not cause symptoms. But as the
cancer grows, symptoms may include:
• A lump, or nodule, in the front of the neck near the Adam's apple;
• Hoarseness or difficulty speaking in a normal voice;
• Swollen lymph nodes, especially in the neck;
• Difficulty swallowing or breathing; or
• Pain in the throat or neck.
• These symptoms are not sure signs of thyroid cancer.
• An infection, a benign goiter, or another problem also could cause
these symptoms.
31. Staging of thyroid cancer
TNM staging for differentiated thyroid carcinoma
• T Primary Tumor
• TX Primary cannot be assessed
• T0 No evidence of primary tumor
• T1 Limited to thyroid 1cm or less
• T2 Limited to thyroid 1cm less than 4cm
• T3 Limited to thyroid more than 4cm
• T4 Beyond thyroid capsule
32. • N Regional lymph node
• Nx Regional lymph node cannot be assessed
• N0 No regional lymph node metastasis
• N1 Regional lymph node metastasis
• M Metastasis
• Mx Cannot be assessed
• M0 No metastasis
• M1 Metastasis present
33. Clinical Staging
Stage Under 45years Over 45 years
I Any T, any N, M0 T1, N0, M0
II Any T, any N, M1 T2,N0,M0 or T3,N0,M0
III T4,No,M0 or Any T,N1,M0
IV Any T, Any N, M1
Only patients over 45 years have stage III and IV
34. Treatment of thyroid cancer
• The choice on the procedure depends on type, differentiation and stage at
presentation; patients are generally regarded as low risk or high risk;
Low Risk
• Female patients aged less than 50 years and male less than 40 years.
• Patients with Papillary Ca, Follicular Ca (cytological suspicious), tumor less
than 1.5 to 2 cm, confined to one lobe, and without metastases.
• Surgical intervention for low risk thyroid cancer is Lobectomy or Near total
thryoidectomy.
• There is higher recurrence rate with lobectomy although the overall
survival between patients who undergo total near total thyroidectomy is
not significant to those with lobectomy.
35. High Risk
• Female patients aged more than 50 years and male patients more
than 40 years.
• larger, bilateral tumors or metastases.
• patients with Papillary Ca (extrathyroidal), Follicular Ca (widely
invasive) and Medullary Ca are considered as high risk.
• Surgical intervention for high risk patients is usually total
thyroidectomy or near total thyroidectomy with neck lymphnode
excision (central) or Modified radical neck dissection.
• This is followed by postoperative thyroxine 100Umg/day to suppress
TSH in patients with thyroid hormone dependant thyroid cancers
(papillary and follicular cancer)
36. • Note that medullary carcinoma is neither TSH dependant nor
radioiodine sensitive.
• Suppression of TSH reduces risk of recurrence and also
improves survival.
• Radioactive iodine I131 can also be used post operative to
ablate all metastatic cells or tumor cells left during surgery.
• A period of hypothyroidism is achieved by stopping thyroxin
for a month to increase tumor cells sensitivity to radioactive
iodine.
37. •For poorly differentiated (anaplastic)
carcinoma of the thyroid; surgery (total
thyroidectomy) can be tried if the patient
presents early, this should be followed by
chemoradiation.
•In advanced cases chemoradiation is the
mainstay of treatment.
38. Prognostic indicators in patients with
differentiated thyroid carcinoma
• 10 years survival for middle-aged adults is about 80 to 95%,
• 5 to 20% have local or regional recurrences while 10 to 15% have
distant metastases.
• The main survival determinants include;
• age more than 45 years,
• growth or type of tumor (pathology, differentiation), and extent (micro vs.
widely invasive),
• size of the tumor less or more than 1.5cm
• presence of metastasis and
• completeness of surgical removal.
