Our body cells are continually growing, dying and being replaced.  Cancer is the result of a breakdown in the normal growth of body cells.  Normal growth is regulated by our genes.  Some genes programme for cell growth (oncogenes) while others stop growth (tumour suppressor genes).  There are several ways in which a normal cell can become a cancerous cell:

• The growth, oncogenes, may become overactive.
• The tumour suppressor gene is underactive or even switched off completely.
• The rate of change from normal to faulty genes is increased.  This may be due to a fault in the way the body repairs faulty genes or increased damage to genes, as occurs with carcinogens such as tar products from tobacco.

Whether a damaged cell becomes a cancer is a complex process, involving changes in several types of genes.  Whether a cancer cell spreads depends on the type of cancer, local inflammation, immune response and tumour promoting growth factors.

Once a tumour is established, it may spread locally and to other sites/parts of the body (metastasise).  Treatment depends on the tumour, its size and whether it has spread or not.  Treatments include surgery, radiation, and drugs (chemotherapy).

Cancer can develop as a result of factors related to environment, lifestyle, and heredity. While our current understanding of the causes of cancer is incomplete, many risk factors that increase the possibility of getting cancer have been identified. These include:

• Age (half of all cancers are diagnosed in patients aged 69 years and over);
• History of cancer in the family;
• Tobacco use;
• Excessive alcohol consumption;
• Lack of balanced diet, in particular insufficient consumption of fruit and vegetables;
• Lack of physical activity and/or obesity;
• Ultraviolet radiation from sunshine or sunbeds;
• Exposure to certain chemicals such as asbestos, benzene or radon gas;
• Exposure to ionising radiation;
• Infections such as human papillomavirus, Hepatitis B, Helicobacter Pylori;
• Treatments such as exposure to oestrogen through Hormone Replacement Therapy;
• Late or lack of reproduction in women;
• Lack of breast feeding in women;

Many of these risk factors can be avoided however others, such as age and inherited risk factors, are unavoidable. However, as we age we can help protect ourselves by avoiding further risk factors where possible and by getting regular checkups so that, if cancer develops, it is likely to be found early. Of the remaining avoidable factors some, such as tobacco use, can increase the risk of getting cancers of the lung, mouth, throat, oesophagus, stomach, pancreas, kidneys, bladder and cervix by a significant amount while others increase the risk only by a slight margin.

Commonly discussed possible causes such as non-ionising radiation (such as that from mobile phones) or other electromagnetic fields (such as those emitted by electricity pylons) have not been proven to have a carcinogenic effect.

Further details on risks and protective factors for each of the main cancers can be found in Cancer Causes and Prevention(pdf).

Non Melanoma Skin Cancer, which is easily treated and rarely causes death, accounts for a quarter of all cancers diagnosed in Northern Ireland. In males, the serious cancers of the trachea, bronchus and lung account for 1 in 8 of all cancers diagnosed, with an average of 687 cases diagnosed each year between 2014 and 2018. In females a fifth of all cancers diagnosed are breast cancer, with an average of 1,443 cases diagnosed each year between 2014 and 2018. Lung cancer in females accounts for 13% (626 per year) of all cases diagnosed in women. 

Unfortunately almost anyone can develop cancer, even children and young adults who lead active, healthy lives.  The largest number of cancers occur in the 65+ age group.

Incidence of cancer among people aged 65 years and over N. Ireland

Incidence of cancer by age – 2006-2010 N. Ireland

The number of cases of cancer has increased 34% between 1993 (8,397 cases) and 2010 (11,269 cases).

The increase is because of:

1. More people in the population.
2. More older people in the population (cancer is more common in older persons).
3. Increases in particular cancers such as prostate cancer - 473 cases in 1993 increased to 942 cases in 2010.

• Those who smoke have a much higher risk of developing cancer, especially cancers of the lung, throat, mouth, stomach, oesophagus (gullet), pancreas, kidney and  bladder.  In most developed countries, tobacco accounts for as much as 30% of all malignant tumours (World Health Organization).
• Some infections also increase the risk of cancer, Human papilloma Virus (HPV) increases the risk of cancer of the cervix (neck of the womb) and head & neck cancers there is a vaccine for this.  Information on the HPV vaccine can be found on the Public Health Agency website.
• Hepatitis B infection is associated with an increased risk of Liver cancer.  There is a vaccine for this.
• Helicobacter Pylori infection is associated with an increase in Stomach cancer there is drug treatment, triple therapy to eliminate H. Pylori infection.

Cancer Focus Northern Ireland has a very useful website, they also offer a Freephone cancer helpline service on 0800 783 3339 FREE from 9.00am - 1.00pm Monday - Friday and a stop smoking service.

Cancer Research UK has a wealth of information about the charity and about cancer on their website.

National Cancer Institute in the US also has a very informative website.

OncoLink offers multimedia information regarding all aspects of cancer and cancer therapy.  Aims to promote cancer research, to educate and to care for patients with cancer.

Action Cancer provides general information about common cancers, as well as detailing organisation activities such as campaigns, fundraising and events. 

Macmillan Cancer Support provides practical, medical and financial support and pushes for better cancer care.

In order to help prevent cancer, the International Agency for Research on Cancer has developed 12 ways to reduce your cancer risk called European Code Against Cancer.

In the strictest sense of the word, cancer is not a hereditary disease as you will not definitely get cancer if one or more of your parents have had the disease.  You can however inherit a tendency to develop a particular cancer, but even if this inheritance occurs it will not definitely result in that cancer actually developing.

There are 4 types of behaviour.

Benign - this is usually a slow-growing tumour that may displace but does not invade or infiltrate surrounding tissues; a tumour considered not to have malignant or invasive potential.

In-situ - an in-situ tumour is one with malignant potential which has remained confined to the tissue in which it originated.

Invasive - (also known as malignant): an invasive tumour is not (or is no longer) confined to the tissue in which it originated.  Most tumours are invasive.

Uncertain - an uncertain tumour is one which, at the time of diagnosis, cannot be classified as either benign or malignant.