1) In over 60 percent of the time cancer happens due to purely random chance. There is no way to prevent this. And the longer one lives, the longer the chance of such random events, the main reason why cancers are more common as we get older. As we get older, cells had a longer time to acquire mutations, either randomly or from secondary causes.
2) Cancer is caused by mutations within the genes – the machinery that control our cells. Often several mutations are needed before a cell could become cancerous. People with a strong family history of cancers are born with certain important genes like BRCA already mutated, so they have a higher risk of cancer which can also develop at an earlier age. It is important to note here that a strong family history of cancer implies close family members who developed cancer at an unusually early age. Heredity may play a role in about 5 percent of all cancers.
3) Preventable causes of cancer: Unhealthy food habits, smoking, excess alcohol, exposure to virus, chemicals and excessive sun light are some of the most common causes and may contribute to up to 35 percent of all cancers. Since this is the only 35 percent we have any control, it is crucial to modify these risk factors. Of the preventable causes tobacco smoking remains the single most important preventable cause of cancer. When tobacco is combined with excess amount of alcohol, the risk of cancer is multiplied.
4) Diet and cancer: What is generally considered a “heart healthy diet” is also good to prevent cancer. Briefly this mean less processed food, less fat and empty carbs, avoid over cooking, avoid excess amount of pickled food, and increase nuts, fruits and vegetables. A note of caution about fruits is warranted here: Having too much fruits and fruit juice to be avoided as they could rapidly increase blood sugar and insulin levels which is harmful.
5) Exercise. Moderate exercise is shown to decrease recurrent risk of early stage breast and other cancers. By decreasing inflammation and improving insulin sensitivity of cells, moderate exercise could help especially against the so called “metabolic syndrome related” cancers. These include cancers of the breast, endometrium, prostate, ovary, colon, and esophagus. As obesity, type 2 diabetes and other life style related illnesses increase in a population, it is often associated with a corresponding increase in the incidence of these metabolic syndrome associated cancers also.
6) Many viruses are implicated as the cause of several common cancers (examples being Hepatitis B causing liver cancer, HPV causing oral and cervical cancers). If a vaccination is available against such virus – as is the case of Hepatitis B and HPV – it could be one of the steps to prevent cancer.
7) We are discovering increasingly the role of immune surveillance in cancer, and immune based therapies for cancers are now becoming common place. Diseases that depress immune system increase the risk of cancers. And there is emerging data which suggest immune system could also be decreased by previously unacknowledged issues including psychological stress, lack of adequate sleep and so on.
8) Commonly implicated cause of cancer in social media like cell phones and other factors: Very little if any actual data in humans. Reasonable to avoid excessive use especially for children but in general these are much less risky (if any risk at all) than known agents like over cooked meat and tobacco.