SNC 2D - 2.7 Cancer

Minds on – what do you already know? Cancer What is it? Treatment Types Causes Prevention

Cancer Cells divide out of control Do not respond to inhibitory signals which stop cell growth Hereditary Genetic predisposition to a type of cancer, runs in families Example _______________________ Environmental Triggered by environmental factors “carcinogens” Example _________________________

Causes Damage to DNA or mutation Damage happens in part of DNA that codes for cell cycle Uncontrolled cell division sometimes leads to formation or lump of cells called a tumour. This mass of cells divides with no benefit to the body.

Tumours Tumour cells are like healthy cells They need nutrients and oxygen to survive and go through the cell cycle. They need access to a blood supply…..

Tumours take over The send out chemical signals to normal cells in the surrounding area These healthy cells respond by encouraging nearby blood vessels to expand into tumour mass

Detecting Cancer Difficulty Rate of Growth – doubling times The appearance of cancer (when the mass of cells is detectable) occurs long after cells start to irregularly grow and develop. The appearance of symptoms depends on how fast the cancer cells are dividing Rate of Growth – doubling times Measured in doubling times One doubling time is the time it takes for cancer cells to double in number Varies from 10 days to several years Average doubling time for a cancer is 4 months

Tumours Tumour Uncontrolled growth of cells create a mass Benign tumour Cells of a tumour that stay together and have no affect on surrounding tissues Becomes disruptive when it crowds nearby cells and tissues affecting normal function

Tumours Malignant tumour Metastasis Interferes with functioning of neighboring cells and tissues such as enyme or hormone production In some cases can destroy surrounding tissues Metastasis When cells break away from original tumour and move to different parts of body This is the process by which cancer can move from one part of the body to another

Types of Tumours

Calculating cancer growth If it takes 30 doubling times for a cancer to form a tumour that is large enough to be felt through the skin with hands. Calculate How many months How many cancer cells it would take to form a tumour that can be felt if the doubling time is 2 months. # Doubling times (n) Months (n x 2) # cancer cells (2n) 1 2 3 30

Causes of cancer Genetic interitance Some breast cancers and colon cancer Environmental factors – Carcinogen Promotes mutation Lifestyle Example _______________________________ Radiation exposure _______________________________________ Viruses