But it now appears that at least some of this may be wrong -- that African-Americans are less likely than whites to survive breast, prostate and ovarian cancer even when they receive equal treatment, according to a large study conducted at Loyola University.

The first-of-its-kind study, involving nearly 20,000 cancer patients nationwide, found the gap in survival between blacks and whites disappeared for lung, colon and several other cancers when they received identical care as part of federally funded clinical trials. But disparities persisted for prostate, breast and ovarian cancer, suggesting that other factors must be playing a role in the tendency of blacks to fare more poorly.

"There is good news and puzzling news in our results," said Kathy Albain of Loyola University, whose findings were published online Tuesday by the Journal of the National Cancer Institute.

"When there's a level playing field with the same quality of care, African-Americans survive just as well as other races from some of our most common cancers, which is reassuring news and points us nationally toward a need to make sure there is quality of care and equal access to all," Ms. Albain said. "But for prostate, ovarian and breast (cancer), it's not access to care. There's something else. And we need to sort that out."

Other researchers called the findings groundbreaking.

"I believe this is a landmark analysis," said Lisa Newman of the University of Michigan. "There seems to be something associated with racial and ethnic identity that seems to confer a worse survival rate for African-Americans. I think it's likely to be hereditary and genetic factors."

Some experts immediately cautioned the study could not rule out the effects of socioeconomic and environmental factors earlier in life, warning The Washington Post that the findings could reinforce old prejudices.

"When I hear scientists talking about racial differences, I worry that it starts to harken back to arguments about genetic inferiority," said Otis Brawley, chief medical officer of the American Cancer Society.

Well, bigoted people can and will misuse any data they come across. But there's nothing racist about the underlying findings here, any more than it's sexist to say men are more likely than women to die of heart attacks.

There may indeed still be other factors to control for -- different ethnic groups are known to have different dietary habits, for instance. Mediterranean peoples who eat lots of garlic and olive oil can stay healthier, in later years, than those who don't. The junked-up diets that many poor -- particularly urban poor -- Americans consume in their younger years might also be worth a look as a factor in their lower long-term survival rates.

But for the most part this appears to be a question of biology -- biology that may hold the answer to those longer survival rates, by dictating different treatment regimens for patients of different races or cultures, once it's more thoroughly understood.

That's not racist. The only thing that would smack of racial prejudice is to ignore such findings out of some concern that they may seem "politically incorrect."

We're all different. Different ethnic groups may have better resistance to certain diseases, but less resistance to others. And finding the causes of those differences may lead to better survival rates for everyone.

But first, we have to overcome the fear of acknowledging they exist.