Glossary

T lymphocytes syn. T cells
subtype of lymphocytes (a form of white blood cells); they develop in the thymus gland and are responsible for the so-called cellular immune response; T lymphocytes play an important role in the direct defense against viral and fungal infections and control the activities of other immune cells (e.g. granulocytes).

therapy optimising trial
a controlled clinical trial (study) that aims to provide the best possible treatment for patients and at the same time to improve and develop treatment options; therapy optimisation is aimed not only at improving the chances of recovery, but also at limiting treatment-related side effects and long-term effects.

thermotherapy
here: targeted overheating of a tumour using laser beams with the aim of destroying the tumour cells and/or enhancing the effect of concomitant chemotherapy/radiation
Example / Relevance Pediatrics: thermotherapy can be used, for example, as eye-preserving local therapy for patients with retinoblastoma.

thrombocytes syn. platelets
blood cells that are responsible for haemostasis; they ensure that, in the event of an injury, the walls of the blood vessels are sealed within a very short time, thus stopping the bleeding.

thrombocytopenia
decreased platelets (thrombocytes) in the blood to levels below the age-appropriate norm (less than 150,000 platelets per microliter of blood); thrombocytopenia is associated with impaired haemostasis, which in turn may lead to increased bleeding tendencies (e.g. nose or gum bleeds, bleeding into the skin (petechiae, bruising) and/or prolonged bleeding time (e.g. after injury). A transfusion of platelets (platelet concentrate) may sometimes be necessary.
Example / Relevance Pediatrics: thrombocytopenia can be a sign of cancer, such as acute leukemia. However, it can also be drug-related (e.g. as a result of bone marrow damage caused by chemotherapy or radiotherapy as part of cancer treatment).

thrombocytosis
abnormally increased number of platelets (thrombocytes); too many platelets can lead to certain complaints and diseases as well as an increased risk of blood clots. However, if the number of platelets exceeds a certain limit, there may also be an increased tendency to bleed.

thymus gland
organ belonging to the lymphatic system below the thyroid gland; part of the bodys own defence system and significantly involved in the development of the immune system, especially during childhood; from puberty onwards, it loses its size and importance.

topoisomerase inhibitors
substances used to treat cancer (cytostatics); they inhibit various enzymes (e.g. topoisomerase I and topoisomerase II) that are involved in the repair of breaks in the genetic material. This way, they block the bodys own repair mechanisms, on which rapidly dividing tumour cells depend. Topoisomerase inhibitors include, for example, the active substances etoposide, etoposiphosphate and teniposide from the group of epipodophyllotoxins as well as topotecan and irinotecan from the group of camptothecines.

translocation
exchange of gene segments between two chromosomes

transplantation
transfer of tissues, organs or cells
References: stem cell transplantation

tuberous sclerosis syn. tuberous sclerosis complex (TSC)
genetic, hereditary (or newly acquired) malformation syndrome; tuberous sclerosis is a multisystem disorder that is characterized (depending on its severity) by skin changes, epilepsy, developmental disorders and increasing mental retardation as well as tumour-like changes in almost all organs.
Example / Relevance Pediatrics: characteristically, tuberous sclerosis is frequently associated with tumours in the brain, (e.g. subependymal giant cell astrocytomas or hamartomas).

tumour
groups of abnormal cells forming a growing lump, both benign and malignant

tumour lysis syndrome
metabolic changes due to tumour cell death as a consequence of cancer treatment, usually with large masses or cell counts, after chemotherapy; the changes are manifested by increased uric acid, potassium and phosphate levels, as well as a decrease in serum calcium concentrations, which can result in acute renal failure.
Example / Relevance Pediatrics: tumour lysis syndrome can occur mainly in the treatment of patients with leukaemia or lymphoma; for prevention, appropriate treatment-accompanying measures (supportive measures) are carried out.

tumour marker
biological substance (e.g. protein) in the blood or other body fluids, the increased concentration of which may indicate a newly developed tumour or tumor recurrence; tumor markers play a major role in monitoring the course of the disease in patients who presented with elevated concentrations of a certain tumour marker at the time of cancer diagnosis. Tumour markers are not proof of an existing cancer, because on the one hand, they also occur naturally in the body, and on the other hand they do not necessarily rule out a tumour if they are missing (i.e. not present in conspicuously elevated concentrations).
Example / Relevance Pediatrics: tumour markers in neuroblastoma are the catecholamine metabolites vanillic and homovanillic acid as well as dopamine.

tumour suppressor gene
gene that controls cell division (via its gene product) and thus prevents the formation of uncontrollably growing tumour cells (e.g. TP53 gene or retinoblastoma gene, RB); the failure of a tumor suppressor gene, e.g. due to mutation, can promote tumour formation.
Example / Relevance Pediatrics: Retinoblastoma is caused, for example, by a change (mutation) in the retinoblastoma gene, Li-Fraumeni syndrome (a so-called cancer predisiposition syndrome) by mutation of the tumour suppressor gene TP53.

Turcot syndrome
rare hereditary disease characterized by the appearance of tumours, for example, adenomas in the gastrointestinal tract and brain tumours (medulloblastomas, glioblastomas)

tyrosine kinase
enzymes from the protein kinase family; they particulalrly contribute to the transmission of signals within a cell and are important for embryonic development as well as the regeneration and maintenance of tissues. Functional disorders can play a role in the development of cancer, among other pathological conditions.
Example / Relevance Pediatrics: genetically modified tyrosine kinases play a role in some childhood and adolescent cancers (e.g. the Philadelphia chromosome in leukaemias). Certain drugs, so-called tyrosine kinase inhibitors, are currently being used in cancer medicine to target cancer-promoting tyrosine kinases.