(RxWiki News) Being overweight or obese can increase one’s odds for a number of diseases, including cancer. But it's not only weight that can affect cancer risk; ethnicity may play a role as well.
A new study discovered that being underweight increased a white woman’s risks of dying from breast cancer as did being morbidly obese.
Body mass index (BMI) — a measure of body fat based on height and weight — didn’t seem to affect the death risk of African American and Asian American breast cancer patients.
High waist-to-hip ratios (waist size divided by hip size) did increase risks of dying from breast cancer for Asian Americans, but not for any other race/ethnic group.
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Marilyn L. Kwan, PhD, a researcher with Kaiser Permanente Northern California in Oakland, led this study that investigated the association between body size and breast cancer survival in non-Latina white, African American, Asian American and Latina women.
This same research team recently reported that black women had higher breast cancer rates than white women, but their overall mortality (death) rates were about the same. On the other hand, Asian Americans and Latinas were less likely than white women to succumb to breast cancer.
This study involved 11,351 women diagnosed with breast cancer between 1993 and 2007 and who were followed through 2009.
Data from health and lifestyle questionnaires completed by the participants and the California Data Registry were used for the study.
BMI calculations based on weight and height measurements were taken just over two years prior to breast cancer diagnosis.
Waist-hip measurements were taken an average of almost four years prior to cancer diagnosis and nearly two years following diagnosis. Waist-hip ratios are a measurement of fat distribution.
During the study period, 2,744 women died, and 1,445 of those deaths were related to breast cancer.
In studying the women who died, the researchers discovered the following:
- For white women, being underweight (BMI of less than 18.5) was associated with a 91 percent higher risk of breast cancer death compared to women who were a normal weight (BMI of 18.6 to 24.9).
- Morbid obesity (BMI of 40 or higher) in white women elevated the risk of death from breast cancer by about 43 percent compared to women who were a normal weight.
- For Latinas, only morbid obesity was associated with a higher risk of dying from breast cancer.
- There was no link between BMI and death from breast cancer in African American and Asian American patients.
- Asian Americans with the highest waist-hip ratios had more than a two-fold (2.21 times) greater risk of dying from breast cancer compared to their counterparts who had the lowest waist-hip ratios.
- No waist-hip ratios associations were seen in Latinas, white or African American women.
"Our results suggest that the associations of obesity with mortality vary by measurement and degree of obesity, as well as by race/ethnicity,“ the authors concluded.
"This is an interesting result which suggests that weight maintenance and breast cancer risk are a bit more complicated than we think," Adam Brufsky, MD, PhD, professor of medicine at the University of Pittsburgh, told dailyRx News. "This is all the more reason to for a woman to maintain an optimal weight."
Findings from this study were published in the October issue of the American Journal of Epidemiology.
This research was supported by the California Breast Cancer Research Program.
No conflicts of interest were declared.