Cancer patients may pay special attention to their environment, although this kind of attention may be too late.
Cancer is a genomic disease, but not all the DNA replication errors will cause cancer. Each time a cell divides, there are over 6.2 billion DNA base pairs which need to be copied. In such a vast replication process it is not surprising that some errors may occur even as a part of life’s activities. Only under the influence of the external environment, can these errors cause continuous variations, which eventually develop into cancer. If we make an assessment about the role of the environment and genetic inheritance in cancer, these two factors respectively accounted for 70% to 90% and 10% to 30%. Philosophically speaking, the variations are based on internal factors while external factors
are the conditions of variations. External factors work through internal factors, but internal changes cannot occur without external changes.
According to statistics, 60-70% of cancers are related to inappropriate life habits and customs. These include improper diet, smoking, insufficient exercise and negative emotions. We cannot choose genetic inheritance, but we can change the environment around us so as to reduce the incidence of cancer. Recognizing environmental carcinogenic factors could help to prevent cancer. The World Health Organization declared that, “1/3 of cancer can be prevented,” which refers to the elimination or reduction of the environmental carcinogens. (Figure 3)
Figure 3 Relationship between cancer and environmental factors
Concerning diet, high-fat and high-calorie foods are related to colon, pancreatic and prostate cancer, whereas nutritional deficiencies and high-salt food are related with esophageal cancer and gastric cancer. Too much fried food is also considered a carcinogenic factor. More fruits and vegetables and less red meat can reduce the risk of cancer.
Environmental pollution such as automobile exhaust, toxic minerals and radioactive substances is certainly associated with cancer. During my visit to the Middle East, local friends there always mentioned the Iraq War when we talked about cancer. Friends in Iraq told us that local leukemia patients increased significantly in recent years because the United States used depleted uranium bombshells in the war. But we don't know whether this possibility was according to a statistical survey or they were venting their resentment of the war.
Some food additives are considered to have carcinogenic effects. The ‘cloudy agent’ in food plasticiser is a legal food additive and is made from Arabic gum, emulsifier, palm oil and other food additives. It is generally used in juices, jams, beverages and other foods. But because palm oil is expensive, some unscrupulous manufacturers use a common plasticizer DEHP instead of palm oil to make toxic cloudy agents which are added to foods. Long-term consumption of this may cause reproductive system disorders and cancer.
Infection is the cause of some cancers. Hepatitis B or C virus infection can lead to liver cancer. In Asia, 90% of hepatocellular carcinoma is caused by the hepatitis B virus. It may take about thirty to forty years from the hepatitis virus infection to result in liver cancer (hepatitis-cirrhosis-liver cancer). Nasopharyngeal carcinoma is most common in southern China, 90% of patients are co-infected with EB virus. The incidence rate of cervical cancer is the highest in poor areas, the vast majority are caused by the HPV infection. The anti-HPV vaccine is the world's first cancer-prevention vaccine, which can effectively prevent cervical cancer.
Helicobacter Pylori is recognized by the World Health Organization as a carcinogen. This is a specialized bacterial infection in the stomach. In Asia, the infection rate is 50-70%. Chinese statistics show that the incidence of gastric cancer is consistent with the infection rate of the bacteria.
After I had cancer, I carefully reviewed my living habits. I did not smoke, but I was exposed to a lot of passive smoke; I was poor when I was young and I did not pay particular attention to food, eating whatever was accessible to me. My life had been full of ordeals, stress, and anxiety; I was too busy to exercise causing me to be overweight. It is difficult to say which kind of life habit was related to the cancer occurrence, but all may have a certain relationship.
For a specific patient, it is difficult for us to decide which factor or which several factors are related to the cancer occurrence. But managing to avoid these adverse environmental factors is certainly beneficial for the prevention of cancer recurrence.