Thyroid cancer is a thyroid neoplasm that is malignant. It can be treated with radioactive iodine or surgical resection of the thyroid gland. Chemotherapy or radiotherapy may also be used.
Thyroid cancers can be classified according to their
histopathological characteristics. The following variants can be
distinguished (distribution over various subtypes may show regional
variation):
- Papillary thyroid cancer (75% to 85% of cases ) - often in
young females - excellent prognosis
- Follicular thyroid cancer (10% to 20% of cases
- Anaplastic thyroid cancer (Less than 5% These types have a
more favorable prognosis than the medullary and undifferentiated types.
- Papillary microcarcinoma is a subset of papillary thyroid
cancer defined as measuring less than or equal to 1 cm. The highest
incidence of papillary thyroid microcarcinoma in autopsy series was
reported by Harach et al. in 1985, who found 36 of 101 consecutive
autopsies were found to have an incidental microcarcinoma. Michael
Pakdaman et al. report the highest incidence in a retrospective surgical
series at 49.9% of 860 cases. Management strategies for incidental
papillary microcarcinoma on ultrasound (and confirmed on FNAB) range
from total thyroidectomy with radioactive iodine ablation to observation
alone. Harach et al. suggest using the term "occult papillary tumor" to
avoid giving patients distress over having cancer.It was Woolner et al.
who first arbitrarily coined the term "occult papillary carcinoma" in
1960, to describe papillary carcinomas ≤ 1.5 cm in diameter.
From the 1940s to 1960s, external, low-dose radiation to the
head and neck during infancy and childhood was used to treat many
benign diseases.
This type of therapy has been shown to predispose persons to
thyroid cancer. The younger the patient was at time of exposure, the
higher the risk of developing cancer.
Another cause may be due to high-dose irradiation to the
head and neck. Patients with
Hodgkin lymphoma treated with mantlefield
irradiation have an increased risk of developing thyroid cancer,
although
hypothyroidism is more likely.
Further Reading
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"Thyroid cancer"
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