(Reuters)
Updated: 2007-09-05 04:52

NEW YORK - In a study of prostate cancer patients living in California, most Asian men with the disease survived longer than their white counterparts. The exception was men from South Asia; their survival was worse than that of white men.

In an interview with Reuters Health, Dr. Anthony S. Robbins, from the California Cancer Registry in Sacramento, said that few studies have compared prostate cancer risk factors and survival between Asians and whites. He added that "there are zero that looked at Koreans, Vietnamese, and South Asians."

He said that his group was surprised at "how much better nearly all the Asian groups fared compared to whites."

The study involved an analysis of data for 108,076 whites and 8840 Asians who were diagnosed with prostate cancer from 1995 to 2004. The cohort included six of the largest ethnic subgroups of Asians: Chinese, Filipino, Japanese, Korean, South Asian, and Vietnamese. South Asians included men from southern India, Pakistan, Bangladesh, Sri Lanka, Nepal, Bhutan and Sikkim.

The overall 10-year prostate cancer-specific death rate was 11.9 percent, according to the report in the medical journal Cancer. The researchers were surprised by "how much variation there was across the Asian groups, all the way from an 8 percent risk of death over 10 years in Japanese men to a 16 percent risk in South Asian men."

All of the Asian groups had worse risk factor profiles than whites, yet only in South Asian men did the profile correspond with poorer survival. "For the groups with better survival, it was paradoxical," said Robbins, "because their risk factor profiles were all going in the wrong direction ... you would have thought they would do worse than whites."

Nonetheless, "The take-home message is that for five out of six Asian groups, 'being Asian' was a favorable prognostic factor for prostate cancer survival," Robbins noted.

"Obviously, the main question we are still trying to explain is why these five Asian groups had better survival. What is behind the 'Asian edge' in prostate cancer? Diet? Lower comorbidity? Less overweight/obesity?"