Despite decades of exhaustive research, a cure for cancer still eludes us, and the number of new cancer cases per year worldwide is expected to reach 23.6 million by 2030. But just what causes this insidious disease? Frequently, lifestyle factors act as a trigger, and sometimes, genetic links come into play. In order to gain a deeper understanding of why some people develop cancer and others don’t, let’s take a deeper look at the causes of cancer.
Causes Of Cancer – Cells Gone Rogue
The root cause of cancer is mutations in the DNA within our cells, and DNA contains our genes. Each gene has a specific set of instructions telling the cell exactly what it has to do every day. Normal cells follow a strict pattern of growth, division and death. We call this pre-programmed death apoptosis. When something happens to confuse the instructions our genes give to our cells, the cells stop doing what they’re supposed to do and, instead of dying, continue to grow and divide. This creates many new cells, each of which has the same mutation. This ultimately results in a mass of out-of-control, mutated cells that begin to form a tumour.
But what causes the genes to mutate in the first place?
There are two main types of gene mutations – those you’re born with, and those that occur after birth. Some people inherit genetic mutations from their parents, and these do account for a small percentage of cancers. However, if you’ve inherited a genetic mutation that predisposes you to cancer, this is not a guarantee that you will definitely develop the disease. Your inherited mutation simply means you could be more likely than others to develop cancer when exposed to certain cancer-causing substances.
Most cancers, however, stem from genetic mutations that happen after birth, and which we largely bring upon ourselves. According to the World Health Organization (WHO), a number of unhealthy lifestyle elements can cause gene mutations, including:
- Tobacco use;
- Alcohol use;
- Overweight and obesity;
- An inadequate diet, specifically one lacking in lacking fruit and vegetables;
- Physical inactivity;
- Chronic infections from Helicobacter pylori, hepatitis B virus (HBV), hepatitis C virus (HCV) and some types of Human Papillomavirus (HPV);
- Environmental and occupational risks, including ionising and non-ionising radiation.
Tobacco use (smoking) is the biggest preventable cause of cancer in the world. It has the highest mortality rate of all the cancers and causes approximately 70 percent of lung cancer deaths in the United Kingdom alone. In addition, smoking increases the risk of at least 14 other cancers. These include larynx, pharynx, mouth, nose and sinuses, oesophagus, stomach, kidney, liver, pancreas, ovaries, bowel, cervix, bladder and some types of leukaemia.
Prolonged exposure to ultraviolet (UV) exposure from the sun can cause a variety of skin malignancies, including melanoma. Ironically, radiation given to treat one type of cancer could lead to the development of another type of cancer.
Pathogen infections can cause several cancers. The most common of these include liver cancer from a Hepatitis B and C infections, gastric or stomach cancer from Helicobacter pylori infection, cervical cancer from a Human Papillomavirus (HPV) infection and Burkitt’s lymphoma from an Epstein Barr infection.
Obesity and Overweight
Extra fat in the body produces growth factors and hormones that affect the way our cells work. Many types of cancer are more common in people who are overweight or obese. Three of these are the hardest to treat – pancreatic, oesophageal and gallbladder cancers. Other types include bowel, uterus, breast, ovarian, kidney and liver cancer, among others. More than 1 in every 20 cancer cases in the UK is linked to being overweight or obese.
Being physically active helps lower oestrogen levels in women. This hormone can lead to the development of breast and womb cancer, so reducing the levels can help reduce the risks of these types of cancer occurring. In addition, being active also helps reduce the amount of insulin in our blood. Scientists believe insulin can stimulate the signals that tell our cells to multiply, so, because cancer starts when cells start to multiply uncontrollably, lower insulin levels could stop certain cancers from developing.
Age is not an unhealthy lifestyle choice, and it’s not strictly a cause of cancer. However, because cancer can take decades to develop, it is more common in older people. This makes age a definite risk factor for the disease.