What is Cancer?

Normally, cells grow and divide to form new cells. When these cells become old or damaged, they die and are replaced by new cells. This process is controlled by genes. However, sometimes, this orderly process does not occur. Old and damaged cells do not die, and new cells continue dividing even when the body does not need them. As a result, a mass of tissue—a ‘tumour’ or ‘lump’—is formed.cancer-new-tr

This tumour or lump can be benign or malignant. Benign tumours are not cancers, while malignant tumours are made of cancer cells. Benign tumours usually grow slowly and do not spread to other parts of the body, while malignant tumours grow more quickly and invade adjoining parts of the body or spread to other organs. A cancer cell is a cell with the ability to grow out of control and invade other tissues. In most cases, cancer cells form a tumour; however, in some cases, such as leukaemia, there may not be any tumour. In this book, only malignant tumours or cancers are discussed.

Cause of Cancer

The exact cause of cancer is unknown. What is known is that cancer is caused by damage to the genes that control cell division and growth. All cancers are genetic because they are caused by abnormal genes. This damage to genes is a result of interactions between a person’s genetic factors and external factors, including:

  • physical agents, such as ionising radiation

  • chemical agents, such as tobacco smoke

  • biological agents, such as infections from bacteria and viruses.

Ageing is another factor for the development of cancer. The risk of cancer increases dramatically with age, which is most likely due to a build-up of risks for those cancers that increase with age.

Spread of Cancer

Cancer spreads in three ways:

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  • local spread: cancer invades the surrounding normal tissue

  • through lymph vessels: cancer invades the lymph system and travels through the lymph vessels to other parts of the body

  • through blood vessels: cancer invades the capillaries and veins and travels through the blood vessels to other parts of the body.

Primary and Secondary Malignant Cancers

The location where cancer cells first develop is the ‘primary’ cancer. When these primary cancer cells break away and are carried in the blood or lymph vessels to other parts of the body, this is ‘secondary’ or ‘metastatic’ cancer. This process is called ‘metastasis’. For example, breast cancer can spread to the bones when it is metastatic breast cancer. Metastatic or secondary cancers contain original cancer cells.

Types of Cancer

There are many types of cancers. These are named after the cells or tissues in which they began. Some types of cancers are as follows:

  • Carcinomas: these begin in the lining of internal organs or the skin.

Examples are squamous cell carcinoma (SCC) and adenocarcinoma.

Almost 85% of all cancers are carcinomas.

  • Sarcomas: these begin from connective tissues that support the body organs, such as the bones, cartilage and tendons. An example is osteosarcoma.

  • Leukaemia: this arises from blood cells.

  • Lymphomas: these arise from lymph tissues.

Genetic and Inherited Cancer

All cancers are genetic because cancer is caused by abnormal genes. When a damaged gene is passed from one generation to another, it is said to be inherited. For example, FAP and hereditary breast and ovarian cancer are inherited cancers. Only a very small percentage of cancers (five to 10%) are inherited.

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Please note that a new book on cancer ‘DO I HAVE CANCER?’ is now available for sale in many online stores around the world. This book is a ‘one stop shop’ for cancer information. If you would like to get a copy of the book, you can click on the links below:

Balboa Press, Amazon, Barnes & Noble

Or if you are in Australia, you can order a copy of the book for AUD 20.00 including postage charge by ordering at: nareshparaj@hotmail.com. You will be sent a payment link through PayPal and the book will be posted upon  receiving payment.