الفهرس 
Aetiology of malignant tumors of the thyroid glandOnly 14 pages are availabe for public view
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Abstract
The incidence of thyroid carcinoma is reported to be
36 to 60 new cases per million populati.on per year. The
incidence of thyroid carcinoma in clinically evident solitary
thyroid nodules that are surgically resected varies from 10
to 30 percent. Thyroid carcinomas demonstrate a 3 : 1 female
predomince. An increasing awareness of thyroid carcinoma and
refinements in the histological diagnosis of carcinoma by
pa’t.ohlogte’ts would partly responsible for the increasing
i.nc’.dence of care inoma .
Well differentiated carc;nomas derived from the thyroid
follicular cell can be divided into two broad groups on the
basis of their biological behaviour. These two types are termed
” papillary” and” follicular” carcinomas respectively,
various subtypes of papillary and follicular carcinomas
behaved as if they were consequetive stages of malignancy
rather than as separate subtypes.
The diagnosis of malignant tumor is usually obvious
once there has been extra-thyroid spread, when there is ·no
eV;dence of extrnthyroid spread, the erowth except for the
very occasional carcinoma which develops in a multinodular
goitre presents as a clinically solitary nodule.
The factors in the history and physical examination that
lead the physician to suspect cancer include a history of
previous external radiation therapy; the relatively recent
onset of 8 firm, hard, single nodule in the thyroid, and the
obvious presence of cervical lymphadenopathy. Although, women
are more commonly affected than men, nodules are uncommon in
men and are more likely to be cancer. A family history of
thyroid cancer should raise the susnicion of 8 multiple endocrine
neoplasia syndrome.
Except for the determination of thyrocalcitonin in
medullary carcinoma of the thyroid, the only unequivocal
diagnostic tool in thyroid cancer is biopsy. It should be
emphasized that thyroid ultrasonography is a reliable examination
for demonstration of multinodular disease, which can
be valuable in the evaluation of a suspect thyroid lesion.
The comb;nation of findings of a cold, solid thyroid nodule
should stUI be regarded as a strong indication for obtaining
a cellular diagnosis. The opposite finding of warm or cystic
nodules, however, is not a valid indication of benignity.
Fi.nally, it is concluded that both sot nttscann t ng and ultrasonography
are not reliable discriminants’ in the diagnosis of
thyroid cancer. Other diagnostic modalities such as thermography
and lymphography have been employed but are much less
specific.
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The management of thyroid cancer continues to be controversial.
The extent of primary treatment. whether conservative
or total resection of the thyroid gland. the use of elective
neck disection. the use of radionuclide for gland ablation
and the postoperative use of thyroid suppression are questions
which continues to face the managing physician and surgeon.
ewing to the indolent nature of well-differentiated thyroid
carcinoma. it is difficult to draw conclusions concerning the
best method of management.
The goals of sur-g icaI treatment for malignant thyroid
lesions, are both clear-cut and concise viz. no hospital
deaths, no postoperative morbidity and long-term tumor-free
survival.
The results of surgical treatment for most malignant
thyroid lesions are today pleasing for both patients and
surgeon. A meticulous surgical technique should maintain this
level of satisfaction.
There continues to be a lack of general agreement on the
cause. pathology, treatment and prognosis of pat ierrt s wLth
well differentiated thyroid carcinoma. The f’oH owtng factors
have been shown to influence the prognosis of well differentiated
thyroid carcinoma : age, sex, size and extent of primary tumor,
histologic type, presence and extent of capsular invasion, stage.
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extent of surgery and adjunctive postoperative therapy. Because
~\ well-differentiated thyroid carcinoma is uncommon, slow growing
and generally indolent, long-term follow-up studies of large
numbers of patients are necessary to evaluate differing modes
of therapy and other factors that influence survival.
If the routine diagnosti.c fine-needle aspiration biopsy
of thyroid nodules is combined with cellular DNA analysis, it
can be used both as a diagnostic and prognostic exam~nation.
It is concluded that patients with aneuploid differentiated
thyroid tumors have poorer prognosis than patients with diploid
tumors. DNA aneuploidy is associated with the strongest prognostic
factor found namely, age at diagnosis and also tumor size and
grade of differentiation. Tncreased probability of DNA aneuploidy
with advancing age explains at least partially why older
pat;ents with d’fferentiated thyroid care lnoma have poor
i
prognosis.