179717 Role of Vitamin D in Racial Disparities in Breast Cancer Prognosis According to Region and Solar UVB Irradiance: Analysis of 40,369 deaths in 204,494 cases in the United States

Monday, October 27, 2008: 8:35 AM

Edward D. Gorham, PhD , Dept of Family and Preventive Medicine, University of California San Diego, La Jolla, CA
Cedric F. Garland, DrPH, FACE , Dept of Family and Preventive Medicine, University of California San Diego, La Jolla, CA
Sharif B. Mohr, MPH , Department of Family and Preventive Medicine, University of California San Diego, La Jolla, CA
William B. Grant, PhD , SUNARC, San Francisco, CA
Frank C. Garland, PhD , Dept of Family and Preventive Medicine, University of California San Diego, La Jolla, CA
     
INTRODUCTION: Much of the poorer breast cancer survival in black women remains after accounting differential screening and treatment access (Egan KM. Cancer Causes Control. 2008, Grant WB. J Natl Med Soc, 2006 Mar;98(3):357-64). Biological factors, including lower vitamin D levels, adverse estrogen-receptor status, or advanced stage at diagnosis may account for disparities. Vitamin D photosynthesis is one-third as efficient in black compared to white women and vitamin D insufficiency is more than 5 times as prevalent. Low solar ultraviolet B (UVB) irradiance and low serum 25-hydroxyvitamin D are associated with higher breast cancer risk.

METHODS: This study analyzed differences in age-adjusted breast cancer survival rates in women 50 years and older. Analyses were stratified by race, regional solar ultraviolet B irradiance, and disease stage. There were 40,369 deaths occurring in 204,494 cases in the nine NCI SEER regions between 1973-2000. Kaplan-Meier survival analysis, z-tests, and multiple regression were performed.

RESULTS: Five-year case-fatality rates were markedly higher in black women (p < 0.001) and inversely related to solar UVB irradiance (p = 0.08). The greatest stage-specific regional differences in prognosis were in Stage II. Differences by race were observed at all stages, with black women having a poorer prognosis.

CONCLUSIONS: Women residing at high latitudes have lower serum 25-hydroxyvitamin D status (due to lower UVB irradiation). Black women also have reduced ability to photosynthesize vitamin D. These factors may contribute to the poorer breast cancer prognosis in these populations. Further testing of this association should be conducted in cohort studies.

Learning Objectives:
1. Describe variation in survival from breast cancer according to race and latitude 2. Understand the role of pigmentation in vitamin D photosynthesis 3. Understand the importance of measuring serum 25 (OH) D levels in people of color

Keywords: Breast Cancer, Nutrition

Presenting author's disclosure statement:

Qualified on the content I am responsible for because: I am qualified to be an abstract author on the content I am responsible for because I am an epidemiologist who has been working in the field of vitamin D and cancer prevention for the past four years
Any relevant financial relationships? No

I agree to comply with the American Public Health Association Conflict of Interest and Commercial Support Guidelines, and to disclose to the participants any off-label or experimental uses of a commercial product or service discussed in my presentation.

See more of: Cancer Epidemiology
See more of: Epidemiology