More Education Equals Lower Cancer Death Risk

ATLANTA, Sept. 11 -- Having more than a high school education is associated with a lower risk of dying from cancer, researchers here said.

In a database study, men with 12 years of education or less died of cancer at more than twice the rate of those with more years of schooling, according to Jessica Albano, Ph.D., of the American Cancer Society.

There was a similar but lower association for women, Dr. Albano and colleagues reported online in the Journal of the National Cancer Institute.

Race and socioeconomic status are well known to influence mortality in the U.S., but few studies have looked at how they affect cancer mortality, the researchers said.

To fill that gap, they analyzed death certificates and census data for 2001 in 47 states and the District of Columbia, finding 137,708 cancer deaths among 119,376,196 individuals ages 25 through 64.

The lower age limit was chosen to ensure that those in the study had completed their education. The upper limit was chosen because data on educational attainment is more complete for those younger than 65, the researchers said.

To capture the variation in education, Dr. Albano and colleagues considered six levels - zero through eight years of school, nine through 11 years, 12 years, 13 through 15 years, 16 years, and 17 years or more.

But for a broad picture, they compared those with 12 years of education or less to those with more. In that analysis, for all cancers combined, death rates per 100,000 were:

• 214.4 for black men with 12 years of education or less compared with 90.1 for those with more schooling. The relative risk was 2.38, with a 95% confidence interval from 2.33 to 2.43.
• 163.8 for non-Hispanic white men with 12 years of education or less compared with 73.0. The relative risk was 2.24, with a 95% confidence interval from 2.23 to 2.26.
• 148.1 for black women with 12 years of education or less compared with 103.3. The relative risk was 1.43, with a 95% confidence interval from 1.41 to 1.46.
• 128.8 for non-Hispanic white women with 12 years of education or less compared with 73 for those with more schooling. The relative risk was 1.76, with a 95% confidence interval from 1.75 to 1.78.

For each educational level, the researchers found, blacks also tended to do worse than whites.

For example, the death rate per 100,000 people among black women with more than 12 years of schooling was 103.3, while it was 73 among white women with the same educational level. (The relative risk was 1.42, with a 95% confidence interval from 1.39 to 1.44.)

The analysis turned up some novel findings, Dr. Albano and colleagues said.

For instance, black men with 12 years of education or less had a prostate cancer death rate of 10.5 per 100,000, compared with 4.8 for those with more schooling. A similar pattern but with a smaller difference was seen for white men, the researchers found.

The relatively large difference between the educational groups "suggests that modifiable factors associated with lower levels of education may play an important role" in prostate cancer mortality, especially among black men, they said.

A second novel finding was that-in contrast to earlier studies-breast cancer mortality rates were higher among women with less education than among women with more education.

Specifically, the rates for black women were 37.0 per 100,000 for those with less schooling and 31.1 for those with more, respectively, and for white women the rates were 25.2 and 18.6 per 100,000, respectively, Dr. Albano and colleagues said.

A range of possible risk factors might account for the differences, the researchers said, including access to health insurance, smoking habits, body mass index, and recent screening for breast or colorectal cancer.

The study "adds to the wealth of descriptive data on racial disparities in cancer mortality in the United States," according to Sholom Wacholder, Ph.D., of the National Cancer Institute.

But it's unrealistic to conclude that educational attainment in some way contributes to the disparities between blacks and white, Dr. Wacholder said in an accompanying editorial.

It's challenging, he said, to try to estimate the effect of race on educational achievement and equally difficult to estimate what effect increasing a person's educational level has on his or her later risk of death from cancer.

On the other hand, the data might be employed to suggest groups that might usefully be targeted for public health campaigns, he said. Knowing about unequal mortality rates can "provide hints about where a successful public health intervention might have the greatest potential impact," he said.