Imperfect, Imprecise But Useful: Your Race
DENISE GRADY
New York Times, 04/04/2006
''Why not tell the whole truth?'' asked an e-mail message from a reader.
She objected to a study I wrote about last month, which found that young black
women with breast cancer were more likely than whites or older blacks to have
a type of tumor with genetic traits that make it uncommonly lethal.
The reader wasn't buying the idea of a biological difference linked to race.
She said that her sister was a black woman who had recently died young of
breast cancer, and she argued that if black women were less likely than whites
to survive breast cancer, the real reason was more likely to be that blacks
had less money and therefore less access to early detection and treatment.
She was not the only skeptic. Others doubted the existence of any important
genetic differences among races, and some said race itself was a vague and
biologically meaningless term.
These prickly issues come up nearly every time a study suggests a difference
among racial or ethnic groups in the incidence or outcome of a disease or in
the way people respond to medicines. Are such differences genetic? Or do they
reflect disparities in money, education, stress, diet, exercise and access to
health care? Could there be both genetic factors and social ones?
Is there any way to ask these questions without sounding like a bigot or an
oaf?
''It's a very explosive issue,'' said Dr. James P. Evans, director of adult
genetics at the University of North Carolina. ''And for a good reason. The
whole concept of race has been abused blatantly in the past and egregiously
misused in order to accomplish very distasteful ends socially and
politically.''
Even so, Dr. Evans said, there are differences in the distribution of some
genetic factors based on ''continent of ancestry'' (a phrase being used more
and more instead of the overheated word ''race''). The differences are not
ironclad -- many people have mixed ancestry -- and they are getting blurrier
all the time as people from different parts of the world have children
together. In addition, he said, such differences are ''exceedingly unlikely''
to affect intelligence or complex behavioral traits.
But, Dr. Evans continued: ''The question remains, does any of the differential
distribution of gene forms have potential medical significance? I think the
answer is, sure. There may be differentially distributed genotypes that put a
group, in aggregate, at increased or decreased risk for certain diseases or
affect their responses to certain medications.''
Ideally, he said, doctors would like to know precisely which genes in each
individual explain susceptibility to disease. But for most diseases the
science is not there yet.
''In the meantime,'' Dr. Evans said, ''if we can glean some hint from
someone's ancestry, we should use it if it can help us treat them better.''
Nutrition and access to health care probably account for most of the health
disparities among races, he said, with ancestry playing a much smaller role.
But, he added: ''It would be overstating the case to say our ancestry is
meaningless. If you say it doesn't matter, you avoid the whole ugly problem of
its misuse. But I don't think it's intellectually honest to ignore ancestry.''
The National Cancer Institute comes down mostly -- though not entirely -- on
the side of social factors, stating on its Web site, ''Many of the differences
in cancer incidence and mortality rates among racial and ethnic groups may be
due to factors associated with socioeconomic status rather than ethnicity.''
By that reasoning, blaming the differences on biology and ignoring or
diminishing the role of socioeconomics would too easily let society off the
hook for inequalities that clearly do exist.
An editorial in The New England Journal of Medicine in 2001 said race was
a ''social construct, not a scientific classification,'' and denounced ''race-
based medicine,'' including ''medical research arbitrarily based on race.''
The editorial concluded that ''in medicine, there is only one race -- the
human race.''
Such high-minded sentiments sound pretty good. But the same issue of the
journal also included an article and another editorial suggesting there were
some important racial differences in the way people reacted to various
medicines, including drugs used to treat high blood pressure, heart failure,
depression and pain. The differences could affect the dose a person needed, or
whether a particular drug should be used at all. No study says race is an
absolute predictor. But if you come from a particular racial background, you
may be more likely than someone from another background to react in a
particular way to some medicines.
As a patient, I would like to know about this kind of thing. More important, I
would really like my doctor to know about it. If information linked to race
could help somebody even a little, it would seem worth having. But it could be
lost if researchers became wary of studying this subject or even talking about
it.
''I would say there is some hesitancy among folks to wade into this field, for
fear their views will be seen as inflammatory, or misconstrued,'' Dr. Evans
said.
Cancer researchers have been wading in, though. Dr. Lisa A. Carey, the medical
director of the University of North Carolina at Lineberger breast center and
the main author of the study comparing tumor types in black and white women,
said: ''I agree with people who say race is an artificial construct. It has
limited usefulness now, as a proxy for ancestral geographic region.''
But for now, she said: ''It's what we have. If it gives us some information
it's better than no information.''
She added: ''I'm very leery of any perception that there's an either-or
situation here. We're just talking about trying to get a handle on all the
factors that seem to play a role in whether a woman gets breast cancer, and if
so, what kind. The next question is why.''
Dr. Kenneth Offit, chief of clinical genetics at Memorial Sloan-Kettering
Cancer Center in New York, said, by e-mail, ''Increasingly, we are learning
that one's genetic ancestry has an impact on cancer risk.''
For example, Dr. Offit said, studies have linked certain genes to prostate
cancer in black men, and other genes to the disease in whites. Black men are
at greater risk for the disease, and he said some of the genetic differences
may help explain why.
''In cancer, we now look for specific mutations of breast or colon cancer
predisposition genes among those of Dutch, Icelandic, Ashkenazi Jewish,
Finnish, Chinese or Swedish ancestry, just to name a few,'' Dr. Offit said.
Ashkenazi Jews have no more breast cancer than any other group, he said, but
they do have a higher rate of hereditary forms. Knowing what mutation to look
for can help simplify and speed up testing.
People sometimes argue that linking particular mutations to ethnic groups
stigmatizes the groups, Dr. Offit said. But he noted that many groups carry
mutations, and the ones who know about them are a step ahead, because genetic
tests have become a major tool for cancer prevention and early detection.
There is no doubt that medical information linked to race can be twisted and
misused. But if it can also help sick people, we should think twice about
throwing it away.