24.01 Introduction

Cancer is defined as a group of diseases which are characterised by uncontrolled cell proliferation and subsequent growth of abnormal tissue leading to profound changes in physiological function. Cancers can arise from both genetic and lifestyle factors that lead to abnormal regulation in the growth of particular stem cell populations or by the dedifferentiation of mature cell types. This aberrant control of cell division can lead to either a benign tumour, which does not spread to other parts of the body and as such is rarely life threatening or to a malignant tumour which can invade other organs, move to other bodily locations (metastasise) and become life threatening.

In the most recent overview of cancer statistics in Australia, it was noted that in 2005, over 100,000 new cases of cancer were diagnosed with over 39,000 deaths recorded in the same period. The major form of cancer affecting females is breast cancer which accounts for some 27% of all diagnoses in 2005. In males, the predominant cancer type is prostate cancer which accounts for 29% of all diagnoses in 2005. In both sexes, the next biggest killers are colorectal cancer, lung cancer and melanoma. In all, these five types of cancer account for 60% of all cancer deaths in men and women. However, there have been great strides in the development of a raft of treatments which has led to improvement of survival times in sufferers although this has lead to increased disease prevalence. At the end of 2004, over 650,000 living persons had been diagnosed with cancer at some time in the previous 23 years (when national data collection began). This accounts for 1 in every 31 Australians. Indeed, one in three men and one in four women will develop some form of cancer by age 75, a risk that increases to one in two for men and one in three for women by age 85.

There are a number of options available for treatment of cancer with the preferred choice of therapy dependent upon location and type of tumour and the disease stage to which the cancer has progressed.  Preferred treatment options include surgery to remove discrete, localised tumours such as those found in prostate and breast cancers; radiation therapy using ionizing radiation to kill cancer cells and shrink tumours (useful in the treatment of most solid tumours as well as leukaemia and lymphoma); and chemotherapy, the treatment of cancer cells with drugs to destroy them.