There is no one single cause for cancer. Scientists believe that it is the interaction of many factors that causes cancer. The factors involved may be genetic, environmental, or constitutional characteristics of the individual. Here are some of the common causes of cancer.

Tobacco and smoking

Tobacco smoke is made up of thousands of chemicals, including at least 70 which are known to cause cancer.These cancer-causing chemicals are known as carcinogens. Nicotine and hydrogen cyanide are some of the most severe carcinogens found in tobacco. 

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Diet and physical activity

Research has shown that poor diet and lack of physical activity can increase a person’s cancer risk. The World Cancer Research Fund estimates that about 20% of all cancers diagnosed in the US are related to physical fitness, body fat or poor nutrition. Physically fitness and healthy food choices with a focus on plant-based foods are thus recommended.

Ultra Violet radiation

Ultraviolet (UV) radiation is a form of electromagnetic radiation that comes from the sun and man-made sources like welding torches. Most skin cancers are a result of exposure to the UV rays in sunlight. The cells that commonly cause skin cancer tend to be found on sun-exposed parts of the body, Their occurrence is typically related to lifetime sun exposure.

X Rays and gamma radiations can also to some extent cause cancer

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Viruses such as HPVs have a role in causing some cancers of the penis, anus and and vulva. They are linked to some cancers of the mouth too. Again, although HPVs have been linked to these cancers, most people infected with HPV never develop cancer. Only a few do.

Research also shows that nearly all women with cervical cancer show signs of HPV infection on lab tests. Hepatitis B and HIV have also been found to cause cancer. But although HIV does not cause cancer directly, it increases a person’s risk of getting several types of cancer.

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Environmental exposures

Pesticides, fertilizers, and power lines have been researched for a direct link to childhood cancers. Whether prenatal or infant exposure to these agents causes cancer, or whether it is a coincidence, is unknown.

Family history 

Many family cancer syndromes are caused by inherited mutations in tumor suppressor genes. These are genes that normally keep cells under control by slowing down how often they divide (to make new cells), repairing DNA mistakes, or controlling the lifespan of cells.

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