QUESTION: I've heard a lot about the risk of cancer and obesity in the news lately and I'm quite concerned. Is there really a risk to my health and is there anything that I can do to reduce the risk?
Dr Nina says: Lifestyle and cancer risk is something that is making the headlines a lot lately. A recent report by the National Cancer Registry suggests that the incidence of cancer will double in Ireland by 2040. It is true that our population is growing and people are living longer. Both these facts combined mean there are more people in the over-60 age group where cancers more commonly occur.
However there is growing evidence to point to the decline of our lifestyle habits as a rising risk for many types of cancer.
Being obese has been linked with a number of cancers. These include cancers of the breast (after menopause), bowel, pancreas, gallbladder, endometrium (lining of the womb), kidney, oesophagus, thyroid and ovary.
Evidence also suggests that those who are obese may have an increased risk of liver cancer, and certain leukaemias and lymphomas although more studies are needed to confirm this link.
It is also known that those who are obese have a higher risk of a particularly aggressive form of prostate cancer. People who are obese are also believed to have a higher risk of death from or recurrence of certain cancer types.
We are now one of the most overweight countries in Europe second only to Britain in recent tables. Two thirds of Irish adults are overweight and one in four is clinically obese. It is not entirely clear how being obese increases the risk of cancer but there are a number of factors that can play a role.
Fat cells make the hormone oestrogen and we know that higher levels of this increase the risk of breast and ovarian cancer. Those who are obese also have higher levels of the hormone insulin. Many are aware that this ultimately increases the risk of type 2 diabetes but insulin is also thought to help turn on cancer cells. This particularly increases the risk of cancer of the pancreas, kidney and bowel.
Fat cells themselves may produce other hormones which activate cells that encourage cancer growth. Obesity also causes a chronic state of inflammation in the body which may promote cancer growth. Many obese people suffer with chronic acid reflux from the stomach into the oesophagus. This damages the lining of the oesophagus over time, increasing the risk of cancer here. All of the above evidence shows us that fat cells are not simply excess weight but are in fact active tissue that can produce substances that stimulate cancer growth.
Cancer risk in obesity isn't just down to the amount of excess weight carried. Weight held around the middle often referred to as apple shape seems to increase the risk of cancer more that weight held around the lower half of the body or pear shape. Timing of weight gain may also play a role. Overweight children are more likely to become overweight adults and some studies also suggest that weight gained early in life particularly from late teens on may be more likely to increase cancer risk.
So what can be done to reduce the risk? The important thing is to avoid gaining weight in the first place. So once again the health of our children should be highlighted here. Other lifestyle factors can play a role. Alcohol is not only very high in calories, increasing the risk of obesity, but it is also considered to be a group 1 carcinogen meaning it is a potent cancer promoting substance.
Alcohol is associated with an increased risk of cancers of the head and neck, oesophagus, liver, colon and breast. Drinking three to six standard drinks a day increases the risk of breast cancer by 41pc so keeping alcohol well within safe limits can help reduce your risk.
The link between smoking and cancer is well established not only with lung cancer but also cancer of the bladder, mouth, throat, stomach and pancreas. Eating a diet high in fruits and vegetables may also help. These contain high levels of antioxidants which may help reduce cancer risk.
Eating large amounts of red and processed meat can increase the risk of cancer so keep your red meat to less than 500g a week and try to avoid processed meats completely.
Lastly stay active. Regular exercise has been shown to reduce the risk of cancer of the breast, bowel and womb and may help reduce the risk of lung cancer.
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