Some Asians Fare Better with Prostate Cancer in US

< Aug. 15, 2007 > -- Your outlook for surviving prostate cancer may depend on your racial and ethnic background, a new study suggests.

Published in the medical journal, Cancer, the study shows that compared to Caucasian men, most Asian ethnic groups - except South Asians - have better outcomes at the time of diagnosis. The study is the first to report prostate cancer survival data for Korean, South Asian, and Vietnamese men living in the US.

"Nearly all Asians do far better when they get prostate cancer," says study lead author Dr. Anthony Robbins, of the California Cancer Registry in Sacramento. "But Indian men didn't do as well as other Asian men, and they did worse than all other men, including blacks and Caucasians," he adds.

Puzzling and Paradoxical

The reasons for these racial and ethnic differences in prostate cancer survival are not known, Dr. Robbins says, adding, "We just couldn't explain it."

Not only can the researchers not explain the finding, they note an apparent paradox. The Asian men were usually older and had more advanced disease at the time of diagnosis, Dr. Robbins states. "Based on their risk factors, you would think they were going to do worse," he says.

Comparing Prognostic Factors

In the study, Dr. Robbins and his co-researchers collected data on 116,916 men (108,076 Caucasians and 8,840 Asians from the six largest represented Asian ethnicities - Chinese, Filipino, Japanese, Korean, South Asian, and Vietnamese) diagnosed with prostate cancer. The researchers compared prognostic factors (which help predict the course of disease) and survival rates among the men.

They found that for Asians, risk profiles were worse compared with Caucasians. For example, Asians were more likely to have more advanced disease and use non-curative therapies. But, for Asians - except for South Asians - survival rates were still equal to or better than rates for Caucasians.

Japanese-American men were 34 percent less likely to die from prostate cancer compared with Caucasians. But South Asian men - those from India, Pakistan, Bangladesh, Sri Lanka, Nepal, and Bhutan - were 40 percent more likely to die from the disease, Dr. Robbins says.

Researcher Considers Why

Some of the factors that may influence the findings include diet, exercise, and genetics, Dr. Robbins speculates.

"Doctors that are seeing patients for prostate cancer need to be aware that these differences can be used as factors in planning the patient's treatment and telling the patient what their survival might be," Dr. Robbins says.

The risk among different Asian ethnicities is poorly understood partly because most studies have grouped all Asians into a single racial category, ignoring the diverse ethnicities that make up Asia.

Interestingly, the most current data has shown that compared to non-Hispanic Caucasian Americans, some Asian ethnicities, such as Japanese-Americans, have higher survival rates, despite worse clinical disease, whereas others, such as Filipino-Americans, have worse survival rates. However, South Asians - e.g., Indians, Pakistanis, Bangladesh, etc. - who represent the third largest Asian subgroup in the US, have never been studied for prostate cancer before.

More Research Needed for Specific Ethnic Groups

Dr. Durado Brooks, director of prostate and colorectal cancer at the American Cancer Society (ACS), thinks this study confirms the need to better understand how different racial and ethnic groups respond to diseases.

"This study points out the potential misleading conclusions we can come to when we use these large groups to lump different subpopulations into," he says.

"If you lump in the South Asian subgroup with other Asians, as is traditionally done, you totally miss the fact that these folks have a strikingly higher chance of dying from prostate cancer," Dr. Brooks says.

Dr. Brooks says the study finding can provide a basis for research to try to understand why these differences exist between populations.

The study should help physicians more accurately apply prognostic factors to their prostate cancer patients.

In conclusion, the study authors say these results argue that traditional prognostic factors for survival from prostate cancer such as stage, grade, treatment, age, year of diagnosis, and socioeconomic status, do not explain why most Asian men have better survival compared to Caucasians. But they do explain the poorer survival of South Asian men compared to Caucasians.

Always consult your physician for more information.