Racial and Ethnic Differences in
Breast Cancer: Eliminating Disparity

The rates of breast cancer, results from treatment, and death rates differ for women from different ethnic groups. In addition to cultural disparities, there may be important differences in the biology of the disease, so research into these questions should help reduce inequality among both women with breast cancer and those at risk for the disease. Such research may also uncover important information that could point to new methods of prevention and treatment. California, with its geographic, environmental, economic, and ethnic diversity, provides one of the best laboratories in the nation or the world for this type of research. This priority issue was added in 2002.

Research in Progress

Two ongoing CBCRP grants in the topic of Racial and Ethnic Disparities reported substantial progress in 2003.

Immune-function Genes and Race Differences in Breast Cancer. Sally Glaser, Ph.D., at the Northern California Cancer Center, Union City, is comparing a type of gene involved in immune function called HLA among California women from various ethnic groups. The goal is to see if HLA genes are responsible for some or all of the differences in breast cancer rates between various ethnic groups. So far, the research team has obtained and begun testing blood samples from 214 premenopausal white, African American, and Hispanic breast cancer patients and 269 premenopausal women from the same ethnic groups who do not have the disease.

Can Placenta Factors Explain Race Patterns of Breast Cancer?
During pregnancy, the placenta is the organ that regulates a baby’s growth and the production of hormones responsible for changes in a woman’s body. Barbara A. Cohn, Ph.D., at the Public Health Institute, Berkeley, previously discovered that if a woman’s placenta has certain characteristics, she has strong protection against breast cancer 40 years later. Her research showed this to be true only for white women. In this project, she is comparing characteristics of placentas of Asian, Hispanic, African American, and white women who were pregnant between 1959 and 1967 to see if differences explain the ethnic groups’ varied rates of breast cancer. She has found that Hispanic and Asian women, who have lower rates of breast cancer, had placentas that weighed less when compared to the birth weight of their babies. White and African American women, whose breast cancer rates are higher, had placentas that weighed more when compared to the birth weight of their babies. This suggests that the underlying cause of heavier or lighter placentas may also be a risk factor for breast cancer.

Research Initiated in 2003

Four new studies were funded in 2003 to examine disparities and options for eliminating the unequal burden of breast cancer among Californians.

Reducing Disparities among Korean American Women.
Low-income Korean American women don’t have mammograms very often or at all, after they have had the first one. Soo-Young Chin, Ph.D., at the Korean Health, Education, Information & Research Center, Los Angeles, and Annette E. Maxwell, Dr.P.H., at the University of California, Los Angeles, are testing ways to educate low-income Korean American women to raise the number of these women who have mammograms at regular intervals.

Racial Disparity in Breast Cancer Mortality.
Over the past decade, the death rate from breast cancer has dropped more for white women than for African American women. Hispanic and Asian women have lower death rates, but their death rates are not improving the way the death rate has improved for white women. Rebecca Smith-Bindman, M.D., at the University of California, San Francisco, will analyze data on 95,000 women diagnosed with breast cancer between 1992 and 2001. She will investigate whether differences at the cell level of the tumors, differences in the women’s use of mammograms, or differences in treatment explain the differences in death rates between ethnic groups.

Lifestyle Factors and Breast Cancer Prognosis in Asian Americans.
Anna H. Wu, Ph.D., at the University of Southern California, Los Angeles, is studying 1,200 Asian American women diagnosed with breast cancer between 1995 and 2000. Her team will investigate the effect of diet (including green tea and soy foods), exercise, and body size—both before and after their diagnosis—on whether these women have had a recurrence of the disease and whether they have survived.

Correlates of Lymphedema Severity and Access to Intervention.
Diane R. Estrin, at the Women’s Cancer Resource Center, Oakland; Linda Wardlaw, at the Charlotte Maxwell Complementary Clinic, Oakland; and Rani B. Eversley, Ph.D., of the University of California, San Francisco, are testing and developing educational materials to help minority women prevent arm pain and swelling (lymphedema) after breast cancer surgery. The need for this research grew out of the study “Return to Work After Breast Cancer Surgery” cited above. Minority women taking part in that study experienced more arm swelling and pain than did white women, and many said they had not been told about the possibility of pain and swelling before their surgery.