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Overview
There is generally no single cause of cancer. Chromosome damage and
inherited or acquired defects in the immune system can play a part.
Ageing leads to a weakening of the immune system, and climate and cultural
practice can also influence incidence. Diagnosis of cancer in people
who have become bereaved in the previous 18 months or so is also common,
suggesting a possible emotional element.
Early Warnings of Cancer
Most infections clear up in time but cancer does not. Consult your
doctor if you have any of these symptoms:
- sores that don't heal
- unexplained swelling
- persistent indigestion or a change in bowel habits unrelated to
diet. If you become aware of a lump or swelling in the abdominal area
- unexplained weight loss of more than 0.5 kg (1lb) a week
- increasing difficulty passing urine
- hoarseness lasting more than a month
- unusual bleeding from mouth, anus, genitals or nipples
- a mole or wart that starts to bleed, gets bigger or changes colour
- a persistent lump or thickening anywhere on the skin
- blood stained sputum; particularly if you smoke
Meat consumption and cancer risk
Eating red and processed meats has been linked with higher risk of bowel
cancer and possibly breast and prostate cancers. One theory is that
cooking meat at high temperatures produces compounds called heterocyclic
amines (HCAs), which are powerful cancer-causing agents in animals.
It is likely they have a similar effect in humans. Also, polycyclic
aromatic hydrocarbons (PAHs) are formed when the fat in food drips on
a flame, heating element or hot coals. These carcinogenic chemicals
waft up in smoke and can land on food, or form directly on food when
it's cooked to a crisp.
Then there's fat. Red meat is a major source of saturated fat, which
has been linked with higher risk of cancers of the lung, colon, rectum,
breast, uterus and prostate. Poultry has not shown an association with
cancer in most studies. Fish can form HCAs but it also contains omega-3
fatty acids, which are associated with reduced cancer risk. Consumption
of red and processed meats should therefore be moderate to zero.
The general emphasis should perhaps be on making meat less of a focus
for most meals and more of an accompaniment to vegetable and grain dishes.
Added Risk from Obesity
Obesity can be implicated directly in the respect that if you are overweight
the physcial detection of a lump can be that much more difficult, particularly
in the breast and abdominal regions.
Obese people tend to be less physically active, so cancer risk may well
be increased. It is, therefore, important to keep weight down through
healthy eating and sensible exercise. Consult a doctor if necessary.
High fat, high risk
High fat diets can enhance colon cancer risk. Recommendations to cut
total fat intake to 30% of energy and to increase Omega 3 fatty acid
consumption in order to reduce risk of cardiovascular disease might
also help reduce bowel cancer rates. Whatever doubts there might be
about a direct link between fats and breast cancer, low-fat diets in
general help reduce obesity, which is itself a cancer risk, as we have
seen above.
Psychological stress and cancer - could they be related?
Some scientists have argued that there is a link between psychological
stress and cancer. Various studies have shown an increased incidence
of early death, including cancer death, among people who have recently
lost a spouse or loved one. However, most cancers have been developing
over many years and are diagnosed only after they have been growing
in the body for a long time (from two to three years). This would appear
to argue against a link between a stressful event and cancer. But it
is known that many types of stress activate the body's endocrine (hormone)
system, which can cause changes in the immune system - the body's defence
against infection and disease - including cancer. This is a 'grey' area
and leads to much speculation.
The immune system is a highly specialised network that is affected by
many factors. So far it has not been shown that stress-induced changes
in the system directly cause cancer. Still, the link between breast
cancer and stress has been studied extensively. Some research has pointed
to higher rates of breast cancer among women who experienced traumatic
life events and losses several years before diagnosis but a direct cause
and effect is extremely hard to prove. It is worth remembering that
stress reduction is of benefit for many other health reasons.
Can alcohol cause cancer?
There is no evidence to support the theory that alcohol causes cancer.
But too much alcohol has so many other bad effects on health that it
is sensible not to drink too much.
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