Cancer is estimated to affect up to one in two people in their lifetime in Ireland, where it currently accounts for about 30% of all deaths. Indeed, the number of new cases of cancer is steadily rising on the back of an ageing population with about 40,000 diagnoses being made last year.
Whilst this may seem grim, survival rates have and continue to improve as a result of screening, earlier diagnosis and better chemoradiotherpy and surgery. A recent study published in The Lancet shows that survival rates in Ireland are now in line with the European average with about 60% living five years or more post diagnosis.
The most common cancer is skin followed by prostate in men and breast in women, with cancer of the bowel and lung being the next most frequent.
While there has been huge advances in cancer care, the ‘war on cancer’ cannot be won alone by investing more in cancer treatments and screening. It is estimated that up to 40% of all cancers could be prevented by modifying lifestyle factors which if addressed could go a long way in reducing new cancer incidence. Better cancer management also means that it is now not uncommon for patients to have a cancer diagnosis more than once in their lifetime.
So what causes cancer? Our cells are dividing all the time to replenish older cells that die but this process is complex and errors occur. When DNA gets damaged some of the genes that regulate cell division are affected and can no longer control the normal cell cycle. This can lead to cells which continue to live indefinitely and replicate uncontrollably giving rise to a tumour.
In the majority of cases exposure to carcinogens in the environment causes this damage which accumulates wth age. For example, smoking or asbestos exposure causing lung cancer, excess sun leading to skin cancer, viruses such as HPV causing cervical cancer and possibly throat cancer.
Chronic damage to cells for other reasons including inflammation may also cause cancer.
The rise in oesophageal cancer has in part been attributed to an increasing prevalence of acid reflux (related to being overweight) which leads to premalignant changes in the lining of the gullet.
It is thought that cancer cells may arise from time to time, especially with increasing age. However, our immune sysytem recognises them as abnormal and generally destroys them. For this reason, patients on immune-suppressing drugs are more likely to get skin cancer.
So what can you do to reduce your risk? While this may seem like another list of “do’s and don’ts” there are some simple practical measures that will substantially lower your risk.
Don’t smoke or inhale second-hand smoke. Smoking is believed to cause about 30% of cancers and is responsible for about 90% of lung cancers. It particularly increases the risk of cancer of the throat and mouth but also of the gullet, stomach, pancreas, liver, colon and bladder.
Risk of cancer can drop by up to 50% within 5-10 years of quitting so don’t think it’s too late to stop. It’s also worth checking if you live in an area with high radon levels as this increases the risk of lung cancer.
Avoid excessive alcohol as it has been associated with an increased risk of developing at least seven cancers. Its not just alcohol-exposed sites such as mouth, throat, gullet and bowel but also breast where risk is increased.
Alcohol is a carcinogen and in particular drinking too much in short space of time leads to the build up of ethanal, a breakdown product which has toxic effects on cells. However, studies show that even after long-term heavy drinking the risk reduces after cutting down alcohol intake. If you combine unhealthy drinking with other factors like smoking, the risk multiplies.
Having a healthy diet may reduce your risk of some cancers. For example, processed meats such as salami, ham and bacon are classified as definite carcinogens by the WHO and higher intakes over many years results in a modestly increased risk of bowel cancer. Red meat might also confer a greater risk so consumption of both should be moderated.
Obesity has been linked to several cancers so you should do regular exercise to avoid weight gain. It is recommended to do 30 minutes of moderate exercise (like brisk walking) five times a week.
Avoid excessive sun exposure, in partcular midday sun when rays are strongest. Remember skin cancer is the commonest and affects about 10,000 people every year in Ireland. Use hats to protect your head in the sun and suncreen should be at least SPF 30. Avoid sun beds and especially sunburn in children.
Vaccination with the HPV vaccine can reduce the risk of cervical cancer and is available to girls in their first year of secondary school.
For some cancers, screening may pick up precancerous growths and hence prevent cancer developing. This is true for both cervical and bowel cancer. Screening for breast cancer can also detect it at an earlier stage and is available from the age of 50 to 64.
Remember, prevention is better than cure so make sure to look after your body.
Dr Kevin McCarroll is a Consultant Physician in Geriatric Medicine, St James’s Hospital, Dublin.