Why Are Urban People More Likely Than Rural People to Get Cancer?
According to general statistics, 25% of China's urban population will develop cancer, while the proportion among the rural population is 21%. The more developed the city, the higher the cancer rate. In first-tier cities such as Beijing, Shanghai, Guangzhou, and Hangzhou, basically one in three people dies of cancer. In some rural areas with relatively healthy lifestyles, cancer remains at a low incidence.
The reasons urban people are more likely than rural people to get cancer are manifold: there are ecological-environmental reasons, and also social-environmental and lifestyle reasons. Modern cities have dense and enormous populations; every large city is an unmatched super-tribe of people, beset with problems: environmental pollution, sexual promiscuity, mental tension, complex social relations, irregular routines, and excessive eating and drinking—all of which can cause a person to develop cancer before he knows it.
From a biological point of view, humans are not suited to surviving in crowded cities; jungle life suits humans better. But one great achievement of the evolution of human civilization has been to pack humans into this "human zoo" (Morris's term) built by humans themselves, living like prisoners in this cement prison, enjoying the conveniences of material civilization on one hand and enduring the anguished struggle of the spirit on the other.
The intensive survival mode of cities leads to urban environmental pollution more severe than in the countryside. Urban water pollution, air pollution, domestic waste, and industrial waste all produce carcinogenic effects. Urban sexual promiscuity is also more severe than in the countryside, because urban people's contacts are broader and more complex than rural people's, and the urban social structure is also unfavorable to restraining human fidelity to sexual partners. Sexual promiscuity causes the spread of oncogenic viruses such as HPV (human papillomavirus); therefore, among urban people, the incidence of sexually related cancers such as cervical cancer is higher than among rural people.
Urban people live long-term in a highly tense interpersonal environment, which is also one of the reasons urban people have a higher cancer rate than rural people. The medical community now generally agrees that excessive mental stress is one of the inducing factors for high cancer incidence. The routines of urban people are also unfavorable to preserving health: urban people generally rest late and are easily overworked at work, all of which make urban people more likely than rural people to get cancer.
Excessive intake of fat and protein and insufficient exercise are also among the reasons urban people are more likely than rural people to get cancer. Obesity-related cancers such as breast cancer and colorectal cancer are generally more common among urban people than rural people, and the incidence is higher in more developed cities.
In addition, average lifespan also has some relationship with cancer incidence: the average lifespan of urban people is higher than that of rural people. Because medical and economic conditions are better, the per-capita lifespan of urban people is noticeably higher than that of rural people, and diseases such as cancer are diseases of the elderly; this factor also pushes up the cancer rate among urban people.