Income, Education, and Breast Cancer

California women who have higher incomes, more years of education, and white-collar jobs get breast cancer more often. Those with lower incomes, fewer years of education, and blue-collar jobs get breast cancer less often. While this holds true for all ethnic groups, income and education make more difference for some ethnic groups than others.

The figures in this section are based on the average income, education, and types of jobs held in the neighborhoods where women lived at the time they were diagnosed with breast cancer. The figures are not based on direct measures of the women's individual income and education.

Income and Education Make a Difference For Some California Ethnic Groups...

The one-fifth of white women with the highest income and most education
get breast cancer 27% more often
than the one-fifth of white women with the lowest income and least education.

The one-fifth of African American women with the highest income and most education
get breast cancer 22% more often
than the one-fifth of African American women with the lowest income and least education.

...And an Even Bigger Difference for Others

The one-fifth of Hispanic women with the highest income and most education
get breast cancer 83% more often
than the one-fifth of Hispanic women with the lowest income and least education.

The one-fifth of Asian/other women with the highest income and most education
get breast cancer 65% more often
than the one-fifth of Asian/other women with the lowest income and least education.

Women with Middle Levels of Income and Education

Women whose income and education levels fall somewhere in the middle generally get breast cancer less often than women with high incomes and more years of education, but more often than women with low incomes and little education.

Why Do Income and Education Matter?

Higher income and more education don't in themselves cause breast cancer. Researchers don't know why women who are wealthier and more educated get more breast cancer, but they have some educated guesses.

Women with more money and education may have better access to health care. This means that when they get breast cancer, their tumors are more likely to be detected and reported. A low-income woman may be more likely to die of another cause before her tumor is detected, and so she wouldn't be counted in the statistics. Another possible cause is that something in the environments or lifestyles of high-income, highly-educated women may lead to more breast cancer.

Women who have children, especially if they have children at a young age or have many children, are less likely to get breast cancer. Low-income women with less education may have more children, and at younger ages. However, even when the figures are adjusted to take childbearing into account, women with higher incomes and more education are still more likely to get breast cancer.

Do Levels of Income and Education Explain Why Some Ethnic Groups Get Breast Cancer Less Often?

Differences in education and income do not explain why women from some ethnic groups are more likely to get breast cancer, and others are less likely. However, some or all of the reasons why income and education make a difference may also be part of the explanation why women from some ethnic groups get breast cancer more or less often.

A Medical Puzzle

For now, the questions of why income and education are related to breast cancer—and why they make more difference for some ethnic groups than others—are a medical puzzle that can only be solved with more research.

Age-Adjusted Breast Cancer Rates

The figures in this section are adjusted for age. Adjusting for age allows the rates to reflect what they would be if the age distribution were the same for California women at every level of education and income. Older women are more likely to get breast cancer. Adjusting for age means that the differences between the education and income levels are not due to there being more older women at some levels of education and income than at others.

How This Research Was Done

Researchers divided the entire state of California into census blocks of about 1,000 people. Using information from the 1990 U.S. Census, they placed each census block into one of five categories. The five categories ranged from the census blocks in the top 20 percent for income, education, housing costs, and whitecollar jobs to the census blocks in the lowest 20 percent. The researchers assigned one of these five categories to each of the 97,227 California women who got breast cancer between 1988 and 1992, based on the women's addresses when they were diagnosed. Using this information, researchers then calculated how often women from each income/education level got breast cancer. Information in this section comes from Chapter 4 of Breast Cancer in California, 2003, “Socioeconomic Status and Breast Cancer Incidence in California,” by Kathleen Yost, Ph.D.