CPT: General principles of Cancer Flashcards
What is cancer?
“Cancer is the rapid and uncontrolled proliferation of cells in the body”
Cancer occurs when existing body cells become abnormal and duplicate out of control
What do the following terms mean?
- Tumour
- Neoplasm
- Oncology
- Tumour - swelling
- Neoplasm - “new growth”
- Oncology - the study of tumours
What can cancer be divided into?
Cancer is not one disease can be classified into 2 broad types
haematological or solid tumours
The following are classifications of tumours. What do each mean?
- Sarcoma
- Lymphoma
- Leukaemia
- Myelomas
- Gliomas
Which do each belong to: solid or haematological tumours?
- Carcinoma - cancer of the covering tissues (skin, lining of the mouth and intestine) (ST)
- Sarcoma - cancer of the supporting tissues (bone, fat, muscle and connective tissue) (ST)
- Lymphoma - cancer of the lymph nodes and other lymphatic tissue (HT)
- Leukaemia - haematological cancers (HT)
- Myelomas- cancer involving the white blood cells responsible for the production of antibodies (B lymphocytes or B-cells) (HT)
- Gliomas- cancer of the brain and spinal cord that begins in glial cells (cells that surround and support nerve cells) (ST)
Describe the difference in properties between benign and malignant diseases
Benign:
- remain confined to original location
- doesn’t invade surrounding tissue or metastasize
- e.g. skin wart
- can be removed by surgery
- generally not life threatening
- except those in inoperable location eg. brain tumors
Malignant:
- referred to as “cancer”
- can invade adjacent tissue and metastasize
- often life threatening
- metastases treat with chemotherapy
What are the common characteisitics of a normal cells?
Common characteristics of cells:
- •Need nourishment
- •Require oxygen
- •Most cells reproduce.
- •Regulated cell death (Apoptosis)
Describe how carcinogenesis occurs (Knudson two – hit hypothesis)
At least two independent events must occur in a cell for it to undergo malignant transformation
Usually separate in time but they can occur simultaneously
A normal cell goes through a series of steps before it becomes a cancer cell. These steps usually include:
- An initiating agent (carcinogen)
- e.g. smoking
- A promoting agent (co-carcinogen)
- e.g. alcohol
- Tumour progression
- Usually occurs over a period of time
Describe the epidimology of cancer
- Cancer was the leading cause of death in the UK
- (2nd to CV-disease).
- 1 in 3 people affected
- men = women
- Every two minutes someone in the UK is diagnosed with cancer.
- Breast, prostate, lung and bowel cancers most common
- Incidence rates in the UK are highest in people aged 85 to 89
What are ateiologies of cancer?
Environmental factors
- Inhaled carcinogens - cigarette smoke
- Ionising radiation - UV radiation-skin cancer; X-rays-acute Leukaemia and Skin carcinoma; Nuclear accidents-acute Leukaemia and Breast Cancer.
- Life-style and diet - processed foods and fats
Genetic factors
- Genetic predisposition has been found to be important for the development and survival rate of some tumours e.g. breast cancer, colon cancer, eye cancer i.e. retinoblastoma
- E.g. mutations in BRCA 1 or 2
Problems with the immune system
- Less able to combat infections by viruses that are linked to the disease.
- Rare genetic diseases that affect the immune system – e.g ataxia telangiectasia or A-T - at higher risk of developing cancer
Describe the steps of the cell cycle
Starting with Go Clinical Pharmacology and Therapeutics 2 Handout Oncology General Principle of Cancer Dr Morag McFadyen e.mail m.mcfadyen@rgu.ac.uk PD3 a quiescent or resting stage eventually progressing to the M phase, the mitotic phase where cell division takes place. The stages of the cell cycle are known as Go, G1, G2, S, G2 and M. In addition there is what is known as the restriction point, R in the G1 phase, this restriction point determines whether a cell progresses through the cell cycle or remains in the Go or early G1 phase. Specialised proteins act as gatekeepers of the restriction point, these proteins allow passage into the S phase where DNA replication occurs leading inexorably to the M stage or mitotic stage where cell division occurs, if and only if they are heavily phosphorylated at serine and threonine hydroxyls
How does a tumour grow?
- Tumour cells do not have a negative feedback mechanism like normal cells that stops cell overgrowth (Apoptosis)
- Cells in certain tissues will divide slower than others.
How does a normal cell turn into a cancer cell?
. . . because of DNA mutation
- inactivation of tumour suppressor genes (suppress malignant changes)
- activation of oncogenes (promote malignancy)
Describe the function of oncogenes and its relation to cancer
Oncogenes
- Genes that normally tell cells to start dividing.
- When oncogenes are activated, they speed up a cell’s growth rate. When one of them becomes damaged, causing cancer, the cell, and all its daughter cells, are permanently instructed to divide.
Describe tumour suppressor genes function and relation to cancer
Tumour suppressor genes
- Normal function the opposite of oncogenes. They stop a cell from dividing, and must be switched off by other proteins before a cell can grow.
- P53 is one of the most important tumour suppressor genes .
Describe suicide genes and their relation to cancer
- Apoptosis - usually occurs when something goes wrong, to prevent damage to neighbouring cell.
- Different genes involved. If these ‘suicide genes’ become damaged, then a faulty cell can keep dividing and become cancerous
Look at cell growth graph
