Cancer is one of the main causes of die in humans. It is estimated that one of two men and one of three women will suffer cancer during their life. We listen to discuss cancer or we know somebody who has cancer, but do we know what cancer is? Then, I explain it.

WHAT IS CANCER?

A malignancy is a tumour. Not all tumours are malignant, there are benign tumours too. A benign tumour does not invade surrounding tissue, while a malignant tumour does it. When a tumour is malignant we call it cancer. If a malignant tumour advances to another tissue it can metastasize, but not all malignant tumours spread.

Cancer can be defined as a group of diseases because it is considered that each one is a different illness. This group of diseases is characterised by an uncontrollably proliferation of cells, caused by genetic mutations. So, cancer is a genetic basis disease. It does not involve that it is also inherited, only 5-10% of cancers is inherited.

Cells have three main pathways where they decide if to live or to die, to divide or not divide and to differentiate or not differentiate. When some of this pathways is broken cancer is produced. There is an abnormal growth where it should not be (Figure 1). It results to interrupt the mechanisms of regulation that govern the normal cellular behaviour.

cancer_all — Figure 1. Evolution of cancer. Firstly, randomly, one cell suffers a genetic mutation. Then, there is a growth of these cancer cells, producing a benign tumor. When this mass advances to another tissue is called malign tumor, and it can metastasize (Source: Cancer Genomics)

TYPES OF CANCER

There are two types of cancer: haematological cancer and solid cancer. Haematological cancers are involved with blood and lymph (leukaemia and lymphoma), while solid cancers are the rest. Inside the group of solid cancer, the most frequents are carcinomas (epithelial tissue) and sarcomas (connective tissue: muscle, bone, fat).

The majority of cancers are carcinomas because epithelial tissue are in constant regeneration and cellular division. This tissue covers or defines the surface of organs, cavities and tubes. Another reason is this tissue is more exposed to carcinogens.

CAUSES OF CANCER

Genetic mutations, which cause cancer, can be produced by external or environmental factors or by internal or intrinsic factors.

In external factors we find physical agents (radiation), chemical agents (diet, tobacco) or biological agents (virus or bacteria). Instead, internal factors can be produced by reparation errors, where random is important. Reparation errors refer to cell’s mechanisms to correct its faults when it replicates. Sometimes, if a mistake occurs, the cell is able to correct it. However, it can always occur that mistake is not repaired that by the likelihood is normal that happens.

Genetic predisposition has to be taken into account because to inherit a mutated gene (inherited cancer) or to have a polymorphism can be done susceptibility to cancer. In the last case, environment is very important.

CAN WE PREVENT CANCER?

Every year around 450,000 people are diagnosed with cancer. This figure refers to incidence, which means the number of new cases for a year. Do not confuse with prevalence, which is the total number of cases (Figure 2). The experts estimate that more than 4 of 10 cases can be prevented, if people change their lifestyle.

incidenceprevalence4 — Figure 2. Representative picture of incidence, prevalence and deaths. Incidence is the new cases in a certain period. However, prevalence is total cases (people with cancer or people being completely healed from cancer) (Source: Epi-demio-logy, modified)

Prevention is the set of actions which have the aim of:

Reduce incidence: around a 40% of cancers can be avoided with healthy lifestyle habits.
Reduce mortality: to detect a cancer in its early stage and to apply treatments more specifics.

We have to be taken into account that healthy living is not a guarantee against cancer. For example, we know that it’s possible for a heavy smoker to live a cancer-free life, while someone who never touches cigarettes could develop lung cancer. But lots of large long-term studies clearly show that people who have never smoked are far less likely to develop or die from cancer than smokers.

12 TIPS TO PREVENT CANCER

Prevention is important because it stacks the odds in your favour, by reducing the risk of developing the disease.

If you initiate healthy lifestyle habits and follow these tips (Figure 3), they can help you to prevent cancer:

Do not smoke: one of three cancers is related to tobacco.
Make your home smoke free: avoid tobacco smoke at workplace too.
Take action to be a healthy body weight: you will also reduce your risk in many other diseases.
Be physically active in everyday life: minimum 30 minutes of moderate intensity.
Have a healthy diet: eat plenty of whole grains, pulses, vegetables and fruits and limit red meat and foods high in salt.
If you drink alcohol of any type, limit your intake: not drinking alcohol is better for cancer prevention.
Avoid too much sun: use sun protection and do not use sunbeds.
Protect yourself against cancer-causing substances by following health and safety instructions, in the workplace.
Take action to reduce high radon levels: find out if you are exposed to radiation from naturally high radon levels in your home.
For women: breastfeeding reduces the mother’s cancer risk. So, if you can, breastfeed your baby. And hormone replacement therapy (HRT) increases the risk of certain cancers. Limit use of HRT.
Vaccination: ensure your children take part in vaccination programmes for hepatitis B (for newborns) and human papillomavirus (HPV) (for girls).
Take part in organised cancer screening programmes for bowel cancer (men and women), breast cancer (women) and cervical cancer (women).

All you need is Biology

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Cancer for beginners: all you need to know