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CNAA / Theses / 2008 / July /

Clinico-morphological aspects of “occult” and incipient thyroid cancer


Author: Adrian Clipca
Degree:doctor of medicine
Speciality: 14.00.14 - Oncology and Radiotherapy
Year:2008
Scientific adviser: Gheorghe Tibirna
doctor habilitat, professor, Public Medical Sanitary Intitution Institute of Oncology
Scientific consultant: Anatolie Cernîi
doctor habilitat, professor, Public Medical Sanitary Intitution Institute of Oncology
Institution:
Scientific council:

Status

The thesis was presented on the 29 July, 2008
Approved by NCAA on the 18 September, 2008

Abstract

Adobe PDF document0.83 Mb / in romanian

Keywords

thyroid gland, occult cancer, thyroid ultrasonography, thyroid arteriography, cytology, histopathology, electronic microscopy, surgical treatment

Summary

The “occult” and the incipient cancer are still an incompletely solved problem in the oncological practice primarily because of the fact that the “occult” cancer frequently manifests as a “hidden” cancer, often in the form of metastases without an identified primary tumor, the differential diagnosis between the incipient carcinoma and a benign nodular growth being difficult. The aim of this work was to emphasize the clinico-morphological characteristics of the “occult” and incipient thyroid cancer so that an optimal algorithm for diagnosing the disease at an early stage could be worked out and a proper therapeutic approach employed. The clinico-morphological findings of 187 patients with histologically-confirmed thyroid cancer and treated in the clinic of the Oncological Institute in the years 1995 through 2006 have been analyzed, all of the patients presenting primary tumors not more than 1.5 cm.

With a view to evaluate the diagnostic importance of the used instrumental investigations and laboratory procedures, the assessment of the sensitivity, specificity, positive predictive value, negative predictive value and the likelihood ratio of the ultrasonic, cytological examinations and thyroid gland arteriography have been performed. The obtained results classify the thyroid gland arteriography as being the most informative procedure in diagnosing the “occult” thyroid cancer which has a sensitivity index of 100 per cent. At the same time, the capacity of cytological investigation to invalidate the presence of the disease is highly appreciated, its specificity index being 87.1 per cent. In conformity with the likelihood ratio of the utilized diagnostic procedures, a diagnostic algorithm for the “occult” and incipient thyroid cancer has been elaborated. According to it, the thyroid gland ultrasound examination is ranked first being the most inoffensive and a sufficiently informative method (likelihood ratio, LR+ = 3,9).

The histological and electrono-microscopic investigations established specific peculiarities of the metastasizing thyroid carcinomas which differ from those non-metastasizing by the presence of vascular invasion, abundance of non-polarized tumor cells, and absence of a peritumoral capsule. Among the non-metastasizing microcarcinomas, a 3-times lower frequency is registered for the papillary carcinomas compared to the follicular ones, while as far as the metastasizing microcarcinomas are concerned, the papillary tumors occur 2.5 times more frequently, are composed of less differentiated cells and show, in most of the cases, an infiltrative growth and absence of encapsulations; nevertheless they are less angioinvasive than the follicular forms. At the same time, other morphological indices such as lymphocytic infiltrates, fibrosis and intratumoral calcinates, as well as manifestations of an oncocytic phenotype characterized by the accumulation of degenerated mitochondria, can not be considered markers of aggressiveness for small-sized thyroid carcinomas.

The surgical treatment of the “occult” and incipient thyroid cancer has been centered round the organ-sparing principle, making use of economical interventions on the thyroid gland and completed, when necessary, with different degrees of regional cervical lymphodissection that permitted to obtain a good survival rate of 5 years in 96.8% of cases.