Everybody knows that there are many causes for cancer because it is a complex and multifactorial disease, due to many factors can provoke cancer. Theses causes can be classified into internal and external ones. The external causes are substances which can increase the risk to generate tumours, they are called carcinogenic and they can be physical, chemical and biological.

The typical factors that generate cancer are tobacco, alcohol, sunbathing and unhealthy food. They are external factors that can be modified. On the contrary, the internal factors cannot be modified, and they are age, sex, race and family history or genetic predisposition. However, these factors must be known to plan a suitable strategy to prevent at the first place and treat secondly through medical check-ups and a change to a healthier lifestyle.

Let’s see the cancer incidence according to certain parameters.


it is obvious that as we are getting older, the risk of cancer is higher since the genetic errors can be easily accumulated and because we are subjected to more carcinogenic agents during all our lifetime.


Some genetic mutations can be transmitted from a generation to the next one, thus we inherit between 5-7% of mutated genes from our ancestors so this way we can have a genetic predisposition to have specific types of cancer. Statistically the 10% of malignant tumours have a genetic origin. Breast Cancer in women (mutated genes like BRCA 1 and 2 can be responsible for this type of cancer).


There are thousands of carcinogenic chemical substances closely related to the industry that can be responsible for the generation of many types of cancer in the developed countries. Environmental Pollution is another external factor to be considered. We can put some examples of those agents such as asbestos, heavy metals, hydrocarbons and coal tars.


Some biological agents are highly carcinogenic like some viruses such as Epstein-Barr Virus (EBV), Human Papilloma Virus (HPV), Hepatitis B and C viruses. Those viruses introduce their own DNA code within a cell to create mutations that can generate tumours. Another example are some fungus such as Aspergillus Flavus that can provoke liver cancer, thus countries where this fungus is developed are where there is a greater occurrence of liver and stomach cancer.


People with low immune activity have a greater risk of certain types of cancer. People with AIDS or those who had organ transplants have a greater risk.


Statistically the cancer mortality is greater in men than in women, because their lifestyle since men tend to take care of themselves less than women. The cancer incidence in men is 207 deaths out of 100,000 people and cancer incidence in women is 145 deaths out of 100,000.  The most common type of cancer in men are lung, colon, rectum, stomach and liver and in women, breast, cervix, uterus, lung and rectum.


The mortality caused by cancer is greater in Afro-Americans men (296/100,000) and lower in Asiatic and Pacific Natives women (91/100,000). More than the 60% of cancer cases come from Africa, Latin America and Asia.


In USA: greater incidence in black population (492/100,000).

In EUROPE: greater incidence in Atlantic Loire area in France (426/100,000).

In PACIFIC AREA: greater incidence in Maori female population (376/100,000)

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In summary, we have internal non-modifiable factors and external modifiable factors in relations to the risk of having cancer, so the strategy will be related to modify the external factors to prevent dangerous connections or synergies with internal factors which must be known in any case.