BOSTON – Obesity increases the odds of a woman with breast cancer dying from her disease, according to a retrospective data analysis.
Further, this link between obesity and breast cancer death is strongest among those obese women who have estrogen receptor (ER) positive cancer, according to the analysis of data on nearly 4,000 participants in the California Teachers Study.
Photo credit: © Kokhanchikov / fotolia.com
Photo credit:© Kokhanchikov / fotolia.comData from nearly 4,000 participants showed that obese women with breast cancer have greater odds of dying from the disease.
"This is another reason why the public should be aware of the importance of maintaining a healthy body weight, particularly how it pertains to cancer and especially breast cancer," according to Christina M. Dieli-Conwright Ph.D., an assistant research professor at City of Hope National Medical Center, Duarte, Calif. She presented the findings at the annual meeting of The Endocrine Society.
The study looked at a cohort of women who had taken a self-administered baseline questionnaire in 1995-1996 and who were diagnosed with their first primary invasive breast cancer between 1995 and 2006. Of the 3,995 women studied through 2007, 262 died of breast cancer and 321 died of nonbreast cancer causes.
There was a significant association between breast cancer mortality and body mass index (BMI) (P = .03). Women who were obese (defined as BMI greater than or equal to 30 kg/m2) had a 69% increased risk of dying of their breast cancer than women with a BMI less than 25. A similar increased risk in breast cancer mortality was seen in women who were overweight at age 18 (defined as BMI 25-29) compared to those with BMI less than 25. No significant associations were noted between weight and deaths due to nonbreast cancer causes or deaths due to all causes.
When the data were stratified according to estrogen receptor status, weight and breast cancer mortality were significantly related among women who were ER positive (P = 0.04), but not for those who were ER negative (P = .41). Obese women who were ER positive had a 64% increased risk of death due to breast cancer compared to those who had BMI less than 25. No significant associations were seen between weight and death due to all causes according to ER receptor status. Interestingly, there was more than a threefold increase in death from breast cancer in women who were ER negative if they were overweight at age 18 years.
Obesity at baseline almost doubled the breast cancer mortality risk (relative risk 1.91, 95% confidence interval 1.27-2.87) in women diagnosed with regional or distant disease, while there was no such association in obese women with localized disease. Higher risk of death from breast cancer and from all causes were also documented for women who had been overweight at age 18 for both localized and regional/distant disease.
Dr. Dieli-Conwright said that the findings add to a growing body of evidence linking obesity with the risk of developing breast cancer and with the risk of dying from it.
Dr. Dieli-Conwright reported having no conflicts of interest.