Cancer is a general term for some 100 diseases characterised by uncontrolled, abnormal growth of cells. This abnormal growth can be viewed as loss of control of the cell cycle and progressive genetic instability. Tumours enlarge because cancer cells lack the ability to balance cell division with cell death (apoptosis). Tumours also form their own vascular system. The transformed cells lose their ability to interact with each other and exhibit uncontrolled growth, invade neighbouring tissues and eventually spread through the blood stream or the lymphatic system to distant parts of the body. Most human tumours lead to death through widespread metastasis rather than the adverse local effects of the primary tumour.

Cancer can develop in any organ from cell types still actively engaged in the cell cycle, and cancer is classified according to the cell type from which it originates: carcinoma (derived from epithelial tissue - the cells covering of the internal and external organs of the body), sarcoma (derived from soft tissues and bone), glioma (brain), leukaemia and lymphoma (derived from blood and lymphatic tissues). Carcinomas are the most frequent type of cancer.

Cancer Treatment

Cancer treatments include surgery, radiotherapy (gamma radiation or X-rays), and chemotherapy. These treatments may be given alone or in combination and are aimed at eliminating the cancer cells - by direct removal in the case of surgery or by causing the cancer cells to die. Chemotherapy uses drugs to destroy the cancer cells. These drugs are designed to kill actively dividing cells. Unfortunately, not all actively dividing cells are cancerous and healthy cells can also be damaged by chemotherapy, leading to the side effects commonly associated with chemotherapy such as reduced white blood cell count (and increased risk of infection) and hair loss.

As anticancer treatments, such as chemotherapy and radiotherapy, are designed to kill cancer cells. Effective treatment is associated with increased numbers of dead cells within tumours. Unfortunately, at the present time, it is difficult for doctors to assess whether chemotherapy is actually causing the cancer cells to die, particularly during the early phase of the treatment regimen. Typically, cancer patients undergoing chemotherapy receive a minimum of three cycles of treatment over 12 weeks before clinical and radiological assessment of tumour response is made. So, chemotherapy patients may face significant side effects from their treatment without knowing whether they are obtaining a benefit. There is also the economic cost of administering medicines that may be ineffective.

When cancer treatment is not curative, as is often the case, maintaining the highest possible quality-of-life is paramount. For many patients, supportive and palliative care is essential.

Monoclonal Antibodies

Monoclonal antibodies are proteins that have the ability to target one specific region of a cell or one specific cellular component. Monoclonal antibodies have been the subject of increasing scientific investigation because of their potential for diagnostic and therapeutic use in humans. When a monoclonal antibody binds to a cell, it can influence cell function and, in some cases, lead to cell death. Alternatively, a monoclonal antibody can be linked to a radionuclide so its position in the body can be identified using the body scan techniques of nuclear medicine.

A major goal for researchers working with monoclonal antibodies is to identify markers specific to cancer cells. A monoclonal antibody specific to cancer cells might have both diagnostic and therapeutic applications. Ideally, we require sensitive discrimination between cancer cells and normal tissue to enable precise targeting to cancer cells.

In practice, therapeutic monoclonal antibodies have demonstrated significant anticancer responses and improved patient survival. Several monoclonal antibodies have been approved by the US Food and Drug Administration for the treatment of cancer.