This reversal largely reflected a faster increase in cancer mortality among men in low socioeconomic areas compared with men in high socioeconomic areas, researchers explain in the June 19 issue of the Journal of the National Cancer Institute.
Europeans have long used socioeconomic data along with mortality rates to identify and monitor health disparities. In the United States, however, cancer mortality rates have not been calculated for different socioeconomic groups, partly because information such as income is not recorded on the death certificate.
To get around this problem, Gopal K. Singh, Ph.D., of the National Cancer Institute, and his colleagues divided all U.S. counties into five socioeconomic categories and linked that information to county mortality data. The socioeconomic categories were based on factors such as education, occupation, median family income, unemployment rate, family poverty rate, and housing condition.
The authors found that between 1950 and 1960, male cancer mortality was nearly 50% greater in the highest area socioeconomic group than in the lowest area socioeconomic group. However, this gap narrowed in the 1970s, and began to reverse in the late 1980s. By 1998, cancer mortality was 19% higher in the lowest area socioeconomic group than in the highest area socioeconomic group. Similarly, substantial changes in area socioeconomic patterns in cancer mortality were seen in women during that period.
The authors note that the socioeconomic patterns in male cancer mortality trends are consistent with socioeconomic patterns in cigarette smoking. "Given the latency period between the start of regular smoking and cancer death, we should expect socioeconomic disparities in male cancer mortality to continue to widen in the near future," the authors say.
In an accompanying article, Singh and his colleagues looked at changing socioeconomic patterns in lung and colorectal cancer mortality among U.S. men and women ages 25 to 64 and age 65 and older. The authors say that these two cancers, which are the leading causes of U.S. cancer mortality, have driven the trends in total cancer mortality.
The researchers found that socioeconomic differences in male lung cancer mortality reversed between 1950 and 1998, in favor of high area socioeconomic groups. In 1950, lung cancer mortality among men ages 25 to 64 was twice as high in the highest socioeconomic group than in the lowest socioeconomic group.
However, the pattern reversed in the 1970s, and by 1998, lung cancer mortality for men ages 25 to 64 was 56% greater in the lowest socioeconomic group than in the highest. Mortality for men ages 65 and older was 38% greater in the lowest socioeconomic group than in the highest.
Lung cancer mortality for women ages 65 years and older in all socioeconomic groups increased sevenfold to eightfold between 1950 and 1998, with higher mortality rates in higher socioeconomic groups. For both men and women, differences in colorectal cancer mortality between the highest and lowest socioeconomic groups narrowed during that time.
The authors conclude that area socioeconomic characteristics could be used to monitor health disparities in cancer outcomes and identify areas for potential cancer control interventions. Future studies will focus on other cancers, such as breast, cervical, and prostate cancers, the authors say.
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Singh G, Miller B, Hankey B, Feuer E, Pickle L. Changing area socioeconomic patterns in U.S. cancer mortality, 1950-1998: part I--all cancers among men. J Natl Cancer Inst 2002;94:904-15.
Singh G, Miller B, Hankey B. Changing area socioeconomic patterns in U.S. cancer mortality, 1950-1998: part II--lung and colorectal cancers. J Natl Cancer Inst 2002;94:916-25.
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