What is Cancer?

A human body is composed of millions and millions of individual cells. At any one time, some of these cells will be lost, need to be repaired or die off (a process called apoptosis). Those cells that can not be repaired will need to be replaced by new cells, formed by cell division. This is all controlled by a complex series of pathways involving many different "stop" and "go" messages. The "go" messages stimulate new cell production, following which the "stop" messages halt production when sufficient new cells have been formed and matured.

A cancer is formed by an excessive growth of abnormal cells, where this normal control of cell division is lost. In other words, there are too man "go" messages, or insufficient "stop" messages. This leads to a growth, called the primary tumour or cancer. Once a primary tumour breaks through normal cell barriers (called basement membranes) it becomes a truly invasive cancer. There is then potential for it to spread to areas away from the main growth, called secondaries or metastases.

Cancers can start for no apparent reason, but there are also a number of risk factors for developing cancer. These can include having other family members with cancer, high alcohol intake and smoking. The most important of these is probably smoking, and everyone should be encouraged to stop smoking and adopt a healthy lifestyle, to reduce their risk of developing a cancer.

Where a cancer has spread to is called its stage, and how abnormal the cancer cells look under a microscope is called its grade. A commonly used staging system is the TNM stage, which stands for tumour, nodes and metastases:

T - Tumour. The size or how far the primary tumour has grown.

N - Nodes. Lymph nodes are spread throughout the body, and are one of the sites cancers can spread to. The staging measures how many and which nodes are involved with cancer.

M - Metastases. Stages the extent and sites of secondary spread.

Both the stage and grade are important prognostic factors (i.e. how likely is the cancer to be cured), and are used to help guide the decisions on how a particular cancer should be treated.

Once a cancer has been diagnosed, individual cases are usually discussed in what is called a multidisciplinary team meeting. Within this team are typically surgeons, oncologists (cancer specialists), radiologists (X-ray and scan specialists), pathologists (experts at diagnosing cancer using microscopy and other methods), nurse specialists (who have a particular interest and training in a specific group of cancers) and coordinators/clerical staff. This team will discuss each cancer case separately and propose a plan to treat each of these cancers. This will then be discussed with the patient, and it is in these face to face discussions that the patient will help to select their final treatment plan.