A new study finds that higher obesity rates in Black women with breast cancer in the U.S. may not explain why only 78 percent survive five years after diagnosis, compared to 90 percent of white women, Reuters reports.

Susan M. Gapstur of the American Cancer Society, who wasn't involved in the new work, told Reuters that the study is the most detailed and well-designed so far.

The findings, released this week in the Journal of Clinical Oncology, used data from a previous breast cancer study that examined 4,500 women, all aged 35 to 64 years old when they were diagnosed. The women were interviewed five years before diagnosis about their weight and more than twice as many Black women as white were obese (27 percent versus 12 percent). After eight years, one-quarter of the Black women in the study had died of breast cancer, compared to 12 percent of white women.

Researchers found a 46 percent higher chance of death in obese white women compared to their normal-weight peers. The same was not found for Blacks, though the data did find a hint that obesity may be linked to cancer death in Black women with advanced disease.  Gapstur told Reuters those results would need to be replicated by further studies in other groups.

 "We don't yet have a clear picture," she said.

Despite unclear conclusions, Gapstur added that maintaining a healthy weight should remain a concern for Black breast cancer survivors.

"It is always important to maintain a healthy weight, for a variety of reasons," she said.

(Photo: David McNew/Getty Images)