Cancer Flashcards
What is cancer?
A collection of diseases where tissue cells divide and grow out of control without stopping and spreading into surrounding tissues. The tissues lose the signal to stop growing and so multiply
What is a benign tumour?
Grow only locally and cannot spread by invasion or metastasis
What is a malignant tumour?
Invade neighbouring tissues, enter the blood vessels, and metastasize to different sites. Multiple genes are involved in the development of fully malignant tumours
What are carcinomas?
Cancers of epithelial origin, e.g. epithelial tissue of skin or of the lining of the internal organs, such as skin or mucous membranes
What are sarcomas?
Cancer of the connective or other non-epithelial tissue e.g. liposarcoma, fibrosarcoma
What are hematopoietic cancers?
Classified as either lymphomas or leukaemia
What are lymphomas?
Occur in the lymphatic system and affect T cells and B cells. Most common lymphomas are Hodgkin’s and Burkitt’s
What is leukaemia?
Cancer cells mainly found in the bone marrow and blood
How do tumours occur?
Arise from accumulated genetic mutations and is a multistep process at both phenotypic and genetic levels, forming a malignant mass. They are monoclonal and are formed by the clonal expansion of a single precursor cell. Can be hereditary, with certain inheritable oncogenes causing activation or deregulation of genes that regulate cell growth
What are carcinogens?
Occur from physical, chemical and biological agents
What causes cancer?
Radiation such as sunlight, UV light, x-rays and radioactive elements can induce DNA damage and chromosome breaks. Chemicals such as smoke can also damage DNA (mutagens). Oncogenic viruses insert DNA or cDNA copies of viral oncogens into the genome of the host target cells. Other risk factors include smoking, alcohol, chronic inflammation, age, obesity, tobacco, diet and immunosuppression. Can occur in humans through genetic or phenotypic alternations
What causes neoplastic transformation?
Activation of growth-promoting proto-oncogenes, specifically growth factor receptors, molecules of signal transduction and transcription factors referred to as oncogenes. Mutate of genes that inhibit growth such as suppressor oncogenes are also responsible. Neoplastic cells (cancer cells) result in an increase in growth factors and growth factor receptors, as well as an increase in signal transduction and activation of transcription in comparison to normal cells
What is oncogenesis?
Occurs when carcinogen induces mutation, which results in a dysfunction of tumour suppressor genes. Results in the loss of ability to repair damaged cells or induce apoptosis which causes cancer to develop. Can also develop through mutation of proto-oncogens into oncogens through carcinogen, where increased GF and GF receptors cause the development of cancer
What are the 4 different stages of tumour development?
Normal cells, benign tumours, epithelial cell membrane degradation and invaded cancer cells.
