Secular trends in mortality from common cancers in the United States by educational attainment, 1993-2001

Abstract

Background: Death rates for the four major cancer sites (lung, breast, prostate, and colon and rectum) have declined steadily in the United States among persons aged 25-64 years since the early 1990s. We used national data to examine these trends in relation to educational attainment.

Methods: We calculated age-standardized death rates for each of the four cancers by level of education among 25- to 64-year-old non-Hispanic white and non-Hispanic black men and women for 1993 through 2001 using data on approximately 86% of US deaths from the National Center for Health Statistics, education level as recorded on the death certificate, and population data from the US Bureau of Census Current Population Survey. Annual percent changes in age-adjusted death rates were estimated using weighted log-linear regression models. All statistical tests were two-sided.

Results: Death rates for each cancer decreased statistically significantly from 1993 to 2001 in people with at least 16 years of education in every sex and race stratum except lung cancer in black women, for whom death rates were stable. For example, colorectal cancer death rates among white men, black men, white women, and black women with at least 16 years of education decreased by 2.4% (P < .001), 4.8% (P = .011), 3.0% (P < .001), and 2.6% (P = .030) annually, respectively. By contrast, among people with less than 12 years of education, a statistically significant decrease in death rates from 1993 through 2001 was seen only for breast cancer in white women (1.4% per year; P = .029). Death rates among persons with less than 12 years of education over the same time interval increased for lung cancer in white women (2.4% per year; P < .001) and for colon cancer in black men (2.7% per year; P < .001) and were stable for the remaining race/sex/site strata. Temporal trends generally followed an educational gradient in which the slopes of the decreases in death rate became steeper with higher educational attainment.

Conclusion: The recent declines in death rates from major cancers in the United States mainly reflect declines in more highly educated individuals.

Figure 1

Temporal trends in age-adjusted US death rates from lung cancer by educational attainment for individuals aged 25–64 years in 43 states and the District of Columbia, 1993–2001. Annual percent change (APC) was estimated and tested for statistical significance using weighted log-linear regression models. The symbols at the right of the lines indicate APCs that are statistically significantly different from 0 at P < .05 (exact P values for all APCs are given in Table 1).

Figure 2

Temporal trends in age-adjusted US death rates from colon and rectal cancer by educational attainment for individuals aged 25–64 years in 43 states and the District of Columbia, 1993–2001. Annual percent change (APC) was estimated and tested for statistical significance using weighted log-linear regression models. The symbols at the right of the lines indicate APCs that are statistically significantly different from 0 at P < .05 (exact P values for all APCs are given in Table 1).

Figure 3

Temporal trends in age-adjusted US death rates from breast (female) and prostate cancer by educational attainment for individuals aged 25–64 years in 43 states and the District of Columbia, 1993–2001. Annual percent change (APC) was estimated and tested for statistical significance using weighted log-linear regression models. The symbols at the right of the lines indicate APCs that are statistically significantly different from 0 at P < .05 (exact P values for all APCs are given in Table 1).