Causes of Cancer

Risk Factors & Causes of Cancer

It is difficult to predict the exact causes of cancer. However, certain factors are known to increase the risk of developing cancer. These are called risk factors. On the other hand, factors that reduce the risk of developing cancer are called protective factors. 

Some causes are outside our immediate control. These include age and family history of cancer. While some of the other factors can be controlled. These include exposure to certain chemicals, diet and weight control. 

Here, we look at some of the causes of cancer.


According to the most recent statistical data from NCI’s Surveillance, Epidemiology, and End Results programme, the median age of a cancer diagnosis is 66 years. A study conducted in the USA shows that 80% of all cancers are diagnosed in people over the age of 55. Age is particularly a factor in cancers like breast cancer, colorectal cancer, prostate cancer and lung cancer. On the other hand, certain cancers like leukemia and bone cancer develop more often in children. 


Drinking excessive amounts of alcohol increases the risk of developing different types of cancer, including that of the mouth, throat, esophagus, larynx, liver and breast. Those who consume alcohol are advised to do so moderately. The more the consumption of alcohol, the greater the risk of developing cancer. 

Exposure to certain chemicals

The chemicals found in substances like tobacco increases the risk for developing cancer. Such substances are called carcinogenic, meaning that they can cause the development of cancer in those who are routinely exposed to them. Some other carcinogens are substances that are used in the workplace, like benzene, asbestos, formaldehyde, radon and. 

In the domestic space, smoke emitted from the burning of fossil fuels like coal, soot and wood dust are also carcinogenic. Consumption of mineral oils, which  are often used in packaged foods as well, also increases the risk of cancer. 


A lot of research has been conducted to find out if any specific types of food cause cancer. We can conclude that people who consume certain types of food are at a higher risk of developing cancer as they may include chemicals found in wine, red meat and tobacco. 


Oestrogen is a female hormone that is naturally produced in the body. It is necessary for certain normal functions of the body. But if produced in excess, it can increase the risk of certain types of cancer. Oestrogen is also given to patients as a part of certain hormone treatments. 

Research has found that excessive oestrogen is a risk factor for breast cancer and endometrial cancer. Increased exposure to oestrogen can be caused by early onset of menstruation, late menopause, being older at first pregnancy and never having given birth. 


When patients receive an organ transplant, they are given drugs to suppress their immune system. This is done to prevent the body from rejecting the new organ. This makes their immune system weak and prevents it from identifying and fighting cancer cells. Patients of HIV also suffer from a weaker immune system which increases their risk of developing cancer. 


Certain viruses, bacteria and viruses cause cancer by disrupting the process by which cells keep their growth and division in check. This leads to excessive cell growth and division which leads to cancer. Viruses can also cause repeated inflammation, which could lead to cancer. Such viruses can be passed on from one person to another through body fluids. 


People who are obese are at a higher risk of developing certain cancers like breast, colon, rectum, kidney, rectum and gallbladder cancer. Following a healthy diet and leading an active lifestyle helps maintain a healthy weight, which in turn helps reduce the risk of developing cancer. 


Exposure to x-rays, radon and other harmful radiation can increase the risk of cancer. This particularly affects people working in environments where such rays are more likely to be  present, like nuclear power plants.


Exposure to UV rays causes skin damage that may lead to cancer. Using tanning beds and extended exposure to sunlight from mid-morning to late noon, increases the risk of developing skin cancer. Although this type of cancer is more common among light-skinned people, people of all skin colours can be affected. 


Cancer usually occurs due to random gene mutations in one or more cells of the body. These genetic mutations can pass on to the family and people who carry such hereditary mutations may not necessarily develop cancer, but their risk of ending up with Cancer is higher than average.