Cancer - What is Cancer & Development

The process of cell growth and cell division leading to the expansion of the cell population

When early cells (for example stem cells or progenitor cells) give rise to specialised cells

The process by which cancers are generated

An accumulation of errors in vital regulatory pathways

Uncontrolled proliferation (cell division and expansion)

Internal and external inhibitory signals that control cell growth and this control is lost in carcinogenesis

Decreased rate of cell death -> the longer a cell lives, the more likely for genetic errors to occur

New blood vessels are essential for a tumour to survive. The growth of new blood vessels is called angiogenesis

• carcinogenesis is a multi step mechanism • results from an accumulation of errors in vital regulatory pathways • uncontrolled proliferation (cell division and expansion) is the core feature of cancer • normal cells are subject to internal and external inhibitory signals that control cell growth • this control is lost during carcinogenesis • cells multiply and acquire additional changes that give it a survival advantage • these changes generate billions of cells • decreased rate of cell death as important for carcinogenesis as increased proliferation as the longer a cell is alive, the more likely for genetic errors that generate cancer to occur • new blood vessels are essential for tumour survival (angiogenesis)

• Cancer of the eye • Certain leukaemias

• Occupational cancers -> lab work, construction, radiographers etc… • Free radical generation • Carcinogens in cigarettes • Mutations in repressor genes and oncogenes • Inherited predisposition • Diet

Changes in genes that have a role in controlling cell growth

Changes in cell signalling pathways with the end result being uncontrolled growth

A gene whose protein product inhibits a cell function

A genes whose protein product contributes to carginogenesis

A gene present in normal cells that can as a result of a mutation become an oncogene

• Aerobic respiration: cells use both sugar molecules and oxygen to make energy • Anaerobic respiration: cells that are anaerobic use sugars to make energy -> formation of toxic lactic acid which kills nearby healthy cells, making room for more cancer cells

• Smoking • Diet • Sex hormones • Increasing age • Family history

Skin cancer (26%) We have a thinner layer of the ozone layer

• USA: 30% of cancer deaths due to smoking • Non smoker who lives w a smoker has a 30% higher risk of dying from lung cancer than when living w a non smoker • Smoking linked to increase in lung, mouth, oesophagus, pharynx, kidney, bladder cancer • Over 40 potential carvinogens isolated from tobacco • 20 year gap between increased tobacco consumption and lung cancer changes

• They are ions/ molecules with unpaired electrons • They are highly reactive and likely to take part in chemical rxns • Superoxide and hydroxyl radicals can partake in unwanted side rxns, causing cell damage • Many cancers thought to be a result of reactions between free radicals and DNA, resulting in mutations that can affect the cell cycle and lead to malignancy

• As free radicals essential for life, body has mechanisms to minimise the cell damage done by them and to repair cell damgage that does occur • The enzyme, superoxidase dismutase, minimises free radical induced cell damage and repairs some of the damage • Antioxidants neutralise free radicals -> vitamins A, C, E are antioxidants

• Fruit and veg (contain antioxidants) are protective against cancers • Eastern diet containing many plant products contains many beneficial ingredients • Western diet, opposite effect • Mediterranean diet: good as high in fruit and veg, red wine (phenols), complex carbohydrates and low saturated fat content

• High fruit and veg consumption associated w decreased risk of many cancers • High fruit and veg linked to low animal fat consumption • Carotenoids, found in many plants, are: rich in antioxidants, precursors of Vit A which hinders cellular proliferation • Plant derived vitamins, A,C,E have antioxidant properties