Cancer

• Cancers demonstrate how important it is that cell division is precisely controlled, as cancers arise due to uncontrolled mitosis
• Cancerous cells divide repeatedly and uncontrollably, forming a tumour (an irregular mass of cells)
• What is a tumour?

  An irregular mass of cells
• Most current cancer treatments/drugs work by controlling the rate of mitosis
• Cancer comprises many different diseases caused by a common mechanism: uncontrolled cell growth
• Once cells have divided enough to repair or replace a piece of tissue they stop dividing
• The rate of cell division can depend on the environment, hormones known as growth factors but also genes
• People can inherit genes that make them more likely to suffer with some cancers
• Genes are a risk factor along with lifestyle choices such as smoking, alcohol, diet and exercise.
• What are some examples of risk factors?

  Smoking, alcohol, diet and exercise
• Carcinogens are any agents that may cause cancer, and if the agent causes cancer, it is described as a carcinogen.
• What are carcinogens?

  Agents that may cause cancer
• What is a carcinogen?

  An agent that causes cancer
• What are the two types of tumours?

  Malignant and benign
• Some tumours grow slowly and is kept in one area of the body, therefore not invading other tissues and are not typically life threatening, these are known as benign tumours and do not cause cancer.
• Benign tumours do not cause cancer
• Some tumours spread through the body, invading and destroying other tissues, these are known as malignant tumours and cause cancer.
• Malignant tumours cause cancer
• Malignant tumours interfere with the normal functioning of the organ/tissue in which they have started to grow.
• Malignant tumours can break off the tumour and travel through the blood and/or lymphatic system to form secondary growths in other parts of the body, this is known as metastasis
• What is metastasis?

  Metastasis is the spread of cancer cells from the primary tumor to other parts of the body.
• Metastasis is very dangerous as it can be very difficult to detect, locate and remove the secondary tumours developed
• Metastasis causes secondary tumours to develop
• What is a mutation?

  A random change to the base sequence of DNA that makes up a gene
• Mutations are natural, random and happen continuously, changing the gene can cause a change to the protein that gene codes for.
• Changes to the DNA nucleotide sequence can cause a gene mutation, which may give rise to a faulty protein, the change in the cell that results from the malformed protein allows subsequent mistakes to happen more often.
• Cancers start when changes occur in the genes that control gene division
• A change in any gene is known as a mutation, and if the mutated gene is one that causes cancer, it is referred to as an oncogene
• What is an oncogene?

  A gene that has the potential to cause cancer.
• Most mutations have little or no effect on the phenotype of organisms aren’t harmful
• Most mutations either result in early cell death (apoptosis) or result in the cell being destroyed by the bodys immune system, which recognises them as foreign cells
• As most cells can be easily replaced, the apoptosis and destroying of mutated cells usually dont have a harmful effect on the body
• In uncontrolled cell division, small uncorrected errors are passed from the parent cell to the daughter cells, and as each generation produces more non-functional proteins from uncorrected DNA damage, mutations accumulate.
• Uncontrolled cell division can lead to uncontrolled growth of the mutated cells, creating a tumour
• The number or chance of mutations can be increased by being exposed to mutagens such as toxic chemicals or ionising radiation, these can cause mutations that can lead to cancer.
• What factors increase the chances or number of mutations?

  Toxic chemicals or ionising radiation
• What are mutagens?


  Agents that cause mutations.
• Cancer treatments can control the rate of cell division in cancer cells by targeting the cell cycle to try and stop it, this will kill the tumour cells and prevent them from dividing further.
• How do cancer treatments kill tumours?

  Control the rate of cell division in cancer cells by targeting the cell cycle to try and stop it
• S phase is the stage in interphase that cause DNA to replicate, an error in this phase can cause the development of tumours. Drugs can be targeted to damage the DNA and kill the cells to prevent the spread of a tumour.