About Cancer

February 4th is World Cancer Day. This year, the aim is to raise awareness about prevention. Cancer is said to affect 1 in 3 people. In the UK alone, it is responsible for 1 in 4 deaths. Understanding what cancer is, it's risk factors, learning about prevention and identifying cancers early on, is crucial to reducing the effects of this devastating condition.

What is cancer?

Cancer can be defined as the uncontrolled division and growth of abnormal cells, which invade surrounding tissues. This leads to the destruction of normal healthy cells. In some cases, a cancer can spread to parts of the body far away from where it started. This is called a secondary tumor or metastasis.

To understand why cancers occur, we have to understand how normal cells function.

The most crucial aspect of any cell is arguably its DNA. DNA can be thought of as a biological molecule that acts a blueprint. Just like with a building, the blueprint explains the shape, size and how different parts will interact with each other. DNA tells each cell whether it will be a hair, tooth, skin, heart, brain or any other cell. It also controls how long each cell will survive and tells it when it should start and stop dividing (for the purpose of growth and or repair). Because DNA is so important, our cells have various protective mechanisms to ensure that instructions encoded withinDNA are preserved.

Cancers occur when either our DNA repair mechanisms are damaged or damage occurs directly within the DNA, and the cell is unable to repair it. In human cells we have two copies of DNA, one from each parent. Having two copies essentially provides us with a kind of backup. If a gene (particular areas of DNA that code for specific instruction) gets damaged on one copy, we can rely on the healthy gene on the other copy. The problem occurs when both copies of a gene become damaged. If the damaged gene carries instructions that control the growth of the cell, then this could result in a cell that begins to divide in an uncontrollable manner. It is important to note that in most cancers it is likely damage occurs to multiple sets of genes, also other factors, for example how surrounding cells interact with the abnormal cell, will influence whether a cancer will occur.

DNA damage can occur in any cell in the human body. The type of cell affected determines the type of cancer. The most common cancers in the UK are breast, lung, bowel and prostate cancer.

What causes cancer?

In order to understand what causes cancer, we need to look at what causes damage to our DNA and/or the DNA repair machinery. External factors that have the potential to exacerbate or propagate cancer are often referred to as carcinogens. Examples are:

o Tar and various other chemicals in cigarette smoke

o Excessive alcohol

o Radiation (Ultraviolet, x-rays)

o Viruses

Carcinogens impair our DNA repair machinery. In most cases, the greater the exposure (i.e. the longer you smoke, the heavier you drink, the more time you spend in the sun without protection), the more damage your doing to your DNA's repair mechanisms, and the more you are increasing your risks of developing certain cancers.

Certain viruses have been implicated in causing particular cancers. The most well known example of this is the Human Papilloma Virus (HPV). Particular strains of this virus are known to be cancer inducing. These strains are thought to cause cancer by incorporating it's DNA into ours. This causes damage to our own DNA. HPV is the main cause of cervical cancer. HPV is normally sexually transmitted and so women who have unprotected sex with multiple partners will increase their risk of exposure to this cancer causing virus.

As well as external factors, our own bodies produce molecules that can damage DNA. These are known as free radicals. They are byproducts of normal chemical reactions in cells. Free radicals are energetic molecules, which can attack and damage DNA.

Sometimes, cancers are more prevalent in certain families. This is because defective genes are passed on to successive generations. For this reason, these individuals should be aware of their susceptibility to cancer and be particularly cautious with potential carcinogens.

Cancer Prevention

Cancer is indiscriminate and devastating in its effects. There are things that we can all do that can minimise our risks of developing cancer.It is estimated that 40% of cancers are preventable by making the following lifestyle changes:

o Quit smoking

o Cut back on alcohol

o Avoid burnt food (barbecue included)

o Avoid excessive sun exposureand use sun protection

o Vaccinations for young girls against the HPV virus

o Use condoms if you or your partner have multiple partners

o Eat lots of fruit and vegetables. The greater the variety the better (because you will have exposure to a greater range of antioxidants).

o Maintain a healthy weight

o Get plenty of exercise (exercise has been shown to reduce the risks of developing breast and bowel cancers)

Warning symptoms

Prevention is paramount. However, it is also important to recognise critical warning symptoms. The following is a list of "red flag" symptoms that indicate you may need to be investigated by your doctor to exclude cancer as a potential cause. If you have any of the following, please visit your doctor:

• Unexplained weight loss
• Severe night sweats
• Coughing up blood
• Problems swallowing
• Hoarse voice
• Rectal bleeding
• Abnormal vaginal bleeding
• Urinary symptoms (particularly blood in the urine)
• Unexplained pain or aching
• A changing mole on your skin
• Unusual lumps or swellings

If you have a family history of cancer, it is important to discuss this with your doctor. In some cases, there may be a need for regular diagnostic tests. Prevention is the ideal, but if you have cancer, catching it early can be crucial to successful treatment.

Further information

This article has focused on what cancer is; it's causes, prevention of cancer and red flag symptoms. We will endeavor to provide further articles focusing on specific cancers and articles dedicated to cancer treatments in the near future.