L.A.'s ethnic diversity is credited for giving the region an edge in everything from global trade to entrepreneurial start-ups. Now, it may even be partly responsible for lower cancer rates.

Incidences of the most common forms of invasive cancer including prostate, breast, lung and colon cancer are lower in Los Angeles County than the nation as a whole, according to data compiled from 1991 to 1995 by the National Cancer Institute and USC's Cancer Surveillance Program.

Prostate cancer, for example, strikes 162.7 men per 100,000 nationwide, but only 152.3 per 100,000 in L.A. County. Among women, 110.9 per 100,000 nationally are stricken with breast cancer, compared with 99.4 per 100,000 in L.A. County.

Oncologists say environmental and lifestyle factors may play a role in the difference, but that ethnic diversity is probably responsible, too.

Los Angeles County has a large population of Asian Americans, notes Dr. Robert Nagourney, director of Rational Therapeutics, a cancer treatment facility in Long Beach. The incidence of prostate cancer among Asian Americans is half that of whites and one-third that of African-Americans, according to USC's Cancer Surveillance Program.

"In Washington D.C., where there is the highest rate of prostate cancer, you will find that they also have one of the largest populations of black men, who are the most likely to develop that type of cancer," said Nagourney, who was among those presenting studies last week at the American Society of Clinical Oncology in Los Angeles last week.

Good weather may also contribute to lower prostate cancer rates here.

"We know for prostate cancer, a sunny climate has an effect on those cancer rates because of vitamin D (from sunshine)," Nagourney said. "But there are likely some factors that are beyond environment and lifestyle that we just don't know about yet."

Smog, for example, doesn't seem tied to higher cancer rates here, said Dr. Dennis Deapen, executive director of USC's Cancer Surveillance Program.

"People think that because Los Angeles has smog, crowding or whatever, that our cancer rates are higher, but in fact they are not," said Deapen.

Deapen also said that the cancer patterns of different immigrant groups can diminish over time.

"When immigrants arrive here, they begin to assume the cancer risks of Los Angeles," Deapen said.

There also are cancer risks associated with specific areas. Nagourney noted that, until a few decades ago, workers in the Long Beach shipyards were at risk of contracting cancer from asbestos used in the shipbuilding process.


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