Cancer has one name, but many illnesses. Cancer is not a single disease, but instead in many different ones linked by the way they begin – when an errant cell from any part of the body starts multiplying without rhyme or reason. Cell multiplication is not normally a problem. It’s a necessary process; cells must divide often, splitting one after another in an orderly way, to provide the constant supply of new cells that the body requires for growth, maintenance and repair.
But sometimes a cell begins multiplying out of control for no good purpose and, if there is no restraint, sooner or later it will create a mass of tissue called a tumour. Failure of apoptosis, the normal process in the body whereby individual cells undergo their programmed cell death, can also contribute to cancer. This ‘ cell suicide’ limits the lifespan of cells; without it, the cells will continue to grow and multiply.
Fortunately, not all tumours are cancerous. If they are benign, the extra cells will stay in one place, generally posing no threat. But if they are malignant, the extra cells may break away, enter the bloodstream or lymph system and land somewhere else far from their origin, where they multiply anew, growing and pressing upon, invading or destroying other tissues. This spread is called metastasis and the type of cancer that arises from it depends on the type of cell that initially went out of control.
When good cells go bad
For healthy cells to turn into cancerous ones, there must be damage to a cell’s DNA, the long coils of genetic material that contain the complete instructions for cell function. For example, uncontrolled cell division can occur if p53, a tumour –suppressor gene whose job is to regulate cell division, is inactivated by changes or mutations in the sequence of protein building blocks that compose it.
Often, cancer reflects the toll of ageing; everyday wear-and-tear affects cells, just as it does the rest of the body, which is why cancer is more common among older people. Sometimes, the trouble starts with an inherited genetic defect that predisposes certain cells to make a mistake when dividing.
But experts estimate that heredity is directly responsible for only about 35 per cent of cancers. Convincing research also suggests that DNA may be altered by repeated exposure to environmental triggers, including tobacco smoke, certain chemicals, metals, gases, radiation, viruses, harmful compounds in foods or as the result of physical inactivity and other lifestyle factors. About 4 per cent of the cancer cases seen in one study were found to be linked to high use of alcohol. Less than 1 per cent were related to insufficient physical activity and about 1 per cent more appeared to be linked to excessive weight gain.
Luckily, when a cell goes berserk, it doesn’t always keep multiplying unchecked. It may repair itself, stop multiplying and die, or be attacked and eliminated by immune cell patrols. Unfortunately, a potential cancer cell can sometimes slip past the immune defences quite easily for a very simple reason: unlike viruses and bacteria, cancer cells are not easily recognized as the enemy. They’re ‘family’ – our own cells gone astray.
The Power to Prevent Cancer
Just as important as continuing discovery of the factors that can cause cancer is the advancing knowledge of what can be done to prevent it. Already, research has shown that many different nutrients and behaviours can help reduce the risk of cancer arising and maintain the critical elements of the immune system at robust levels. Adopting changes and making choices that will help stave off cancer cuts down on the workload of your immune system and makes it easier for your body to recognize and dispose of any errant cells that do develop – before they can spread.
As daunting as cancer can be, medical advances offer much hope. Decades of research have yielded many steps forward in the detection and treatment of cancer, as well as in the measures we can all take to prevent it. The percentage of Australians and New Zealanders dying of cancer began to decline in the 1980s and ‘90s and the trend continues. Medical journals are brimming with studies that are bringing us closer to a clear understanding of the immune system holds great promise for more victories in the fight against cancer. Scientists are exploring several different ways to direct the immune system’s power against cancerous cells using bioengineered immune system products. In addition, vaccines against some types of cancer are in the offering.