The cause of cancer could be due to many factors. There could be one reason or multiple reasons that one gets cancer. According to the Center for Disease Control and Prevention, smoking is the number one cause, and obesity, poor nutrition and inactivity, in combination, is the second cause of cancer in the US. In some cases, inherited genes will be exposed to cancer, while in other cases, genes are disrupted by external environmental reasons, such as smoking, occupational exposure to carcinogens, chemicals and toxins present in the atmosphere, and work hazards, viruses, excessive alcohol consumption, as well as UV and ionizing radiation. Prescription drugs are other leading risk factor that may contribute to a cause of cancer in the U.S. A combination of genetic and environmental factors may cause one to get cancer! What is encouraging is that many cancers that were fatal not long ago are now curable and treatable.

Although there is no specific etiological cause of cancer, different studies show that there are some possible risk factors. The exact cause is not clear yet, but some theories suggest that cancer is the result of multiple factors reacting with each other leading to certain mutation (or damage) in the DNA of a cell leading to uncontrolled growth of that cell.

Cancer could be associated with variety of causes, which include:

  • Excessive alcohol consumption
  • Poor diet
  • Smoking
  • Benzene
  • Toxins present in the atmosphere (aflatoxins)
  • Genetic factors
  • Radiation
  • Obesity
  • Lack of physical activity
  • Viruses

It is not clear as what causes different types of cancer. Lung cancer has been regarded as the most common type of cancer with high mortality rates. According to research, prostate, colon, and lung cancers have been found to attack men at a higher level compared to other types of cancers. On the other hand, women in America are at a greater risk of developing colon, breast, and lung cancers. It is believed that there are certain types of cancers that are more prevalent in specific parts of the world. For instance, stomach cancer has been very prevalent in people living in Japan, while in other areas like the United States, it is very rare. This is mostly attributed to the types of foods consumed in different regions, as well as other factors such as environmental conditions.

Environmental Risk Factors

Exposure to radiation is a major risk factor for cancer. For example, those who are working in the nuclear field and are exposed to radiation are at a higher risk of developing different types of cancers in comparison to people who are not exposed to radiation environments. Occasionally, treatment with radiotherapy for some types of cancers may cause excessive exposure to radiation, thus leading to higher risk of having another type of cancer. This explains why the medical field uses the lowest dose of radiation in diagnosing and treating different types of disorders.

Chemicals also have their role in cancer etiology. There are some chemicals which have been already proven to expose a person to cancer. Those chemicals are known as carcinogenic substances.


Genetics play a role in the cancer etiology. Recent studies have documented that 1 in 20 cases of cancer is linked in some way to certain inherited genes.

Is there any connection between injuries and cancer?

You may hear or read that different types of injuries could be linked to cancer; that is untrue. Recent studies have established that there is no connection between cancer and any type of injury including falls, broken bones, bruises, or any other form of injury. There may be an accidental presence of an injury at the time of a cancer diagnosis, but nothing has proven the connection between them.

Is there a connection between stress and cancer?

Many scientific studies have been done to establish a possible relationship between frequent stress exposure and the risk of cancer. None of those studies has proven a connection.