Molecular Basis of Cancer Flashcards
Acute
Refers to symptoms that start and worsen quickly but do not last over a long time
Biopsy
Removal of a small amount of tissue for examination under a microscope. Only a biopsy can make a definite diagnosis
Carcinoma
Cancer that starts in skin or tissues that line the inside or cover the outside of internal organs
Chronic
Refers to a disease or condition that persists, often slowly over a long time
Leukemia
A cancer of the blood, begins when normal white blood cells change and grow uncontrollably
Lymphoma
A cancer of the lymphatic system, begins when cells in the lymph system change and grow uncontrollably, sometimes a tumour is formed
Polyp
Growth of normal tissue that usually sticks out from the lining of an organ such as the colon
Prognosis
Chance of recovery; a prediction of the outcome of a disease
Sarcoma
Cancer that develops in tissues that support and connect the body, such as fat and muscle
Stage
A way of describing cancer, such as where it is located, whether or where it has spread and whether it is affecting the functions of other organs in the body
Why do cancerous cells have such a high rate of cell division?
Due to the absence of growth factors
Describe the genome instability and mutation of cancerous cells
Increased rate of accumulation of mutations at chromosomal and gene level
Describe replicative immortality in cancerous cells
In most human somatic cells that divide only a limited number of times, telomerase genes are switched off. However, telomerase genes are reactivated in most human cancer/tumour cells, where telomerase is produced and maintains telomere lengths so that the cancer cells divide indefinitely or are immortalised
Telomerase appears to allow cancer cells to evade apoptosis, and is thought that the abnormal retention of telomeres is involved in the development of some types of cancer
Describe the loss of anchorage dependence in cancerous cells
Normal cells must make contact with a suitable substratum before they can attach, spread and proliferate, known as anchorage-dependent growth. Cancer cells are able to proliferate in suspension cultures or in a semisolid medium without attachment to a surface, known as anchorage-independent growth
Describe the lack of contact inhibition and density-dependent inhibition in cancerous cells.
Normal cells display contact inhibition while cancer cells do not. Normal cells proliferate in a culture dish until they make contact with neighbouring cells while cancerous cells continue dividing after contact with neighbours, growing over adjacent cells in disordered, multilayered patterns
Describe the ability of cancer cells to induce angiogenesis
Angiogenesis is the process by which new blood vessels are formed. It is a tightly regulated process which occurs only when necessary, such as during growth or repair. In the event of abnormal regulation, angiogenesis may result in diseases such as cancer.
To develop into larger, potentially metastatic tumours, a growing tumour stimulates the formation of new blood vessels during angiogenesis or vascularisation.
These blood vessels allow for an increased blood flow to the tumour, hence supplying nutrients and oxygen and removing toxic waste products, also providing pathways for cancer cells to spread to other sites in the body
A tumour cell will express angiogenesis-activating protein genes to produce angiogenesis activating proteins
What is metastasis?
Metastasis is a process where the primary tumour cells invade local tissues and blood vessels, and establish secondary tumours called metastases at distant sites
What are the events that occur during metastasis?
- Cancer cells invade surrounding tissues and penetrate through walls of lymphatic and blood vessels, gaining access to the bloodstream
- Cancer cells are transported by the circulatory system throughout the body
- Cancer cells leave the bloodstream and enter particular organs where they estabalish new secondary tumours at distant sites from the primary tumour
How do cancer cells avoid immune destruction?
The immune system has a surveillance role in monitoring and eliminating the vast majority of incipient tumour cells.
While majority of tumour cells are detected and eliminated, a small percentage however can evade immune destruction by disabling components of the immune system that have been dispatched to eliminate them
What are the differences between benign and malignant tumours?
Benign - few genetic mutations, do not cause serious health problems, can be completely removed via surgery, has a well-defined tumour boundary
Malignant - invasive, could impair functions of organs and are cancerous. Systemic treatment like radiation or chemotherapy is required in conjunction with surgery to ensure complete eradication of all malignant tumour cells, poorly-defined tumour boundary
