Superstitions, folk beliefs and religious convictions that keep many black women from seeking medical treatment when they discover breast lumps may help explain why they are more likely than whites to die of breast cancer, a study suggests.

Among those beliefs: Mystical spells cause cancer. Air makes it spread. And God alone can cure it.Previous research has shown that socioeconomic factors, such as low income and poor access to medical care, account for about half the difference in the death rate, said Dr. Donald Lannin, a cancer surgeon at the East Carolina University School of Medicine in Greenville, N.C.

"Our study is kind of unique - it's kind of found the cause for the other half," he said.

The study was published in Wednesday's Journal of the American Medical Association.

In the study of 540 breast cancer patients in rural eastern North Carolina, blacks were about three times more likely than whites to delay seeking treatment until their cancer was advanced. Cultural beliefs were strongly associated with the disparity, the researchers said.

Although these cultural beliefs were strongly associated with low income, "they were even more strongly associated with race," Lannin said. "That means they were even found in some higher-income blacks."

Lannin said he suspects the findings would also hold true for inner-city blacks in the North and West.

The results challenge a school of thought in medicine that suggests that biological differences make tumors more aggressive in black women than in whites - a theory critics call "race medicine."

"It's an additional nail in the coffin of the thought that biology equates with race," said Dr. Otis Brawley, a National Cancer Institute oncologist who is black.

"If we are ultimately going to combat the breast cancer problem in black women, it helps to actually know the real question. These people have done an excellent study to really show that these beliefs are things we really have to overcome."

Many of the cultural beliefs were fundamental religious convictions about God's power to cure; five times as many blacks believed only God could cure them.

Other beliefs stemmed from folklore and culture-based misconceptions about cancer. For example, more than twice as many black patients studied believed cancer spreads when it's exposed to air. And nearly three times as many thought having "thin" or "high" blood - traditional black American folk terms - causes cancer.

Black women with breast cancer are about 15 percent more likely to die from it than are white women with the disease, Lannin said.