Summary:
Leukaemias and lymphomas are ranked first and third respectively, in terms of
incidence, among all cancer-related diseases in childhood. Thymic masses belong
to the rare masses of childhood mesothorax, and their identification raise
suspicions for possible malignancies. Despite the crucial role of thymus in the
function of immune system, there are no available studies in Greece evaluating
the role of thymus in the development of childhood hematopoietic malignancies,
and thus, some aspects of the disease remain, till nowadays, unclear. The aim
of the current thesis was to study, for the first time in our country, the
thymic function of, in respect with the development of childhood hematopoietic
malignancies, based on the data derived from the Nationwide Registry for
Childhood Hematological Malignancies, in the hope of contributing in the
pathogenesis mechanism of these entities. The study sample consisted of 120
children aged 1-15 years (30 T-cell origin ALL, 30 B-cell origin ALL, 60
healthy hospital controls) and the data collection realized during the period
01/01/1996-31/10/1999. According to the results, there was highly significant
reduction of TREC values in T-cell malignancies as compared with B-cell origin
ALL and healthy controls. Therefore, the function of thymus is possibly limited
in children with T-cell origin ALL. Moreover the current study indicates that
there is a pattern of concordance of high TREC values with better disease
prognosis in hematologic childhood malignancies. Subsequently, with a view in
prevention of leukemias and lymphomas in child hood, we researched and
evaluated possible risk factors for the development of childhood hematopoietic
malignancies, namely maternal smoking during pregnancy. We concluded that
although the relationship between the above malignancies and maternal smoking
during pregnancy has been studied in the world literature, the existing
evidence is not conclusive. In this context, we decided to perform a
meta-analysis, including 9,167 cases of ALL, 1,925 cases of AML and 25,221
health controls, deriving from 9 different countries (USA, United Kingdom,
Canada, Australia, France, Greece, Italy, Sweden and Netherlands). There was no
evidence for a statistical significant increased risk for ALL or AML in
children whose mothers used to smoke during pregnancy. Further studies are
required in both national and international level that would contribute
effectively in the thorough understanding of etiology, pathogenesis, prognosis
and therapeutic treatment of the disease in childhood.
Keywords:
Childhood hematopoietic neoplasmas, Leukemia, Lymphoma, Thymus gland, Cellular immuity
