A number of factors have been implicated in the relatively poor cancer outcomes for populations of lower SES. Disparities in cancer incidence by SES can be explained by differential levels of exposure to environmental carcinogens, differences in personal health habits (e.g., cigarette smoking, poor diet, and lack of education regarding health risks), and other sociocultural factors. Some negative health behaviors are more prevalent among people of lower SES, but these behaviors should not be considered only as matters of purely personal choice. One's social environment can pose barriers to awareness and to making changes in behavior. Individuals living in poverty, for example, have poorer access to information regarding cancer risks and health behavior, to nutritious foods that may diminish cancer risk, and to role models in the form of cancer survivors who can relay information regarding help-seeking. On the other hand, individuals living in poverty "tend to concentrate on day-to-day survival and often develop a sense of hopelessness and powerlessness and become socially isolated" (Freeman, 1990, p. 18), all of which may contribute to negative health behaviors and decreased survival.
Poverty or low SES has not been implicated as a direct cause for a higher incidence of cancer, although research has found that it has an adverse relationship to survival rates. The American Cancer Society estimates that cancer survival rates of poor individuals are 10 to 15 percent lower than those of other Americans (American Cancer Society, 1990). For example, more affluent women have a higher incidence of breast cancer, yet their survival rates surpass those for women living under disadvantaged socioeconomic conditions. Some of the proposed reasons for the disparities in survival rates between the groups are that women of lower SES are diagnosed or seek treatment at later stages of the disease, compared to women in higher income brackets. The results of the 1990 U.S. National Health Interview Survey show that "poorer" women (i.e., those whose annual income was less than $15,200) were significantly less likely to receive Pap smears and mammograms within the previous year than women whose income was at least $46,500. The survey reported that the upper-income women were twice as likely to have received a Pap smear and almost three times as likely to have had a mammogram within the previous year compared with women of low SES. It is suggested that poorer people have fewer opportunities to seek preventive care because of life obstacles, such as difficulties in finding a job or having job security, arranging child care, and arranging transportation (Harvard Center for Cancer Prevention, 1996).
Friedell, Linville, and Hullet (1998), in discussing cancer control efforts among low-income women, note that