Blacks and Hawaiians who smoke up to a pack of cigarettes a day have a significantly higher risk of developing lung cancer than people of other ethnic groups, according to a study published today in the New England Journal of Medicine.

The findings are part of an ongoing study, now in its eighth year, that is considered the largest ever examination of the relationship between smoking, lung cancer and ethnicity. It studied 184,000 men and women — roughly half of them in Hawai'i, the rest from California.

The study found that black and Hawaiian men and women who smoke up to 20 cigarettes a day, considered light to moderate smokers, are up to 55 percent more likely than whites to develop lung cancer. Japanese-Americans and Latinos are up to 50 percent less susceptible than whites, the researchers found.

Researchers said the disparity between ethnic groups was more stark among those who smoked less and negligible among those classified as heavy smokers, or those smoking more than 30 cigarettes a day.

The study is being conducted jointly by researchers at the University of Southern California and the University of Hawai'i-Manoa Cancer Research Center of Hawai'i.

Dr. Loic Le Marchand, a UH epidemiologist, said the study included 6,000 men and 8,000 women who reported themselves as having any percentage of Hawaiian heritage. There was no discernible difference between the sexes when comparing the ethnicities. Previous studies showed that in general, men are more likely to develop lung cancer than women.

"We knew before that Hawaiians have a higher incidence rate of lung cancer" regardless of whether they smoke, Le Marchand said. Previous studies have shown that in every 100,000 Hawaiian men, 96 will develop lung cancer. For whites, the rate is 78 per 100,000.

Doctors also have long known that blacks are substantially more likely than whites to develop lung cancer and more likely to die from it.

The lung cancer rates among Hawaiians and blacks who are light to moderate smokers are about the same, Le Marchand said.

REASONS UNKNOWN

Why the two groups have higher incidences than other ethnicities remains a mystery to the researchers. Suspected factors include genetics and habits among the groups.

Le Marchand said the researchers looked at diet habits of the ethnicities as a possible explanation, but found no differences. Among the things examined were the amounts of fruits and vegetables people ate.

"All cigarette-related deaths are preventable, and the department is aggressively addressing this issue," said state health director Chiyome Fukino.

"Unfortunately, this report is yet another study that confirms what we know to be true, that the Native Hawaiian population is overrepresented in the ill effects of various diseases," Fukino said.

The latest statistics "certainly will give us pause to make sure that our messages are appropriately directed," she said.

Sterling Yee, president of the American Lung Association of Hawai'i, said the latest numbers reinforce his agency's core mission to stop people from smoking before they start.

"It's no mystery that smoking kills smokers," Yee said in a release. "The message for our Native Hawaiian population is that they are being killed at a rate higher than almost all other ethnic groups, and they especially should quit."

STUDY FOCUSES ON DIET

The multi-ethnic study is funded by a National Cancer Institute grant. The other UH researchers involved are Dr. Laurence N. Kolonel, the principal investigator for the study, an epidemiologist and deputy director of the Cancer Research Institute; and Lynne R. Wilkens, a biostatistician.

While the researchers have collected detailed information about smoking, the main purpose of the ongoing study is to examine the relationship between diet and health. Methodology included filling out a series of questionnaires over the eight years. Those surveyed also gave blood samples.

CONTROVERSIAL ISSUE

The effect of race on the risk of disease is controversial.

Proponents of the importance of racial differences hailed the researchers' findings as strong evidence that biological differences among races can be significant, making it imperative that research focus on these genetic variations to try to resolve disparities in health. Skeptics, however, said that the study is inconclusive, and that it could just fuel racial stereotyping and divert attention from environmental and social factors that are probably far more important.

Reach Gordon Y.K. Pang at gpang@honoluluadvertiser.com.