New insights into survival outcomes of Asian Americans with cancer
When patients with cancer in eight different Asian American subgroups were examined, their cancer-specific mortality (CSM) was found to be substantially lower than that of non-Hispanic white patients. The findings were published in the Journal of the National Cancer Institute (2015; doi:10.1093/jnci/djv054).
Numerous studies have documented racial differences in deaths from cancer among non-Hispanic whites and African Americans, but little has been known about survival outcomes for Asian Americans with cancer, until now.
"What we have found is that Asian Americans are an incredibly diverse group that cannot be indiscriminately combined together," said lead author Quoc-Dien Trinh, MD, associate surgeon for the Division of Urology at Brigham and Women's Hospital in Boston, Massachusetts, and faculty at the Center for Surgery and Public Health (CSPH).
"With Asian Americans, there is important variation in socioeconomic status, cultural beliefs, and length of time since immigrating to the United States that researchers must take into account."
Although Asian Americans represent only 5% of the entire United States population, they are the most rapidly growing racial group in the country. This is one of the first studies not just to focus on the cancer-specific survival of Asian Americans, but also to break down that population into eight specific subgroups (Chinese, Filipino, Hawaiian, Japanese, Korean, South-East Asian, Vietnamese, and others) for further analysis.
Trinh and his colleagues used Surveillance, Epidemiology, and End Results Program (SEER) data to look at more than 2.5 million Asian American patients with a diagnosis of lung, breast, prostate, or colorectal cancer (the three leading causes of cancer-related mortality within each gender) between 1991 and 2007.
The team found significant differences in cancer outcomes among the Asian subgroups. Specifically, the researchers report that the Japanese subgroup had substantially better survival rates than non-Hispanic whites (especially with regard to prostate, breast, and colorectal cancers), as did those of Filipino and South Asian descent (for prostate and lung cancers, and lung and colorectal cancers, respectively), while the Hawaiian and Korean subgroups did not.
In Chinese and Vietnamese patients, only those with lung cancer had better CSM rates relative to non-Hispanic whites. Overall, most Asian subgroups were less likely to die from cancer than non-Hispanic white patients.
"We found that CSM is statistically significantly lower for Asian Americans than for non-Hispanic whites overall, despite similarities in odds of receiving definitive therapy, and even after adjusting for socio-demographic factors, cancer stage, and treatment," said Trinh. "We've effectively ruled out a number of variables, suggesting instead that underlying genetic or biological differences and/or complex cultural influences may impact survival in Asian American cancer patients."
This study opens the door for future research to better understand why Asian Americans have better CSM than non-Hispanic whites, and to determine whether and to what extent genetic and/or cultural factors are involved.