Asian Americans are known to have disproportionate numbers of liver cancers because of the high incidence of hepatitis B in that population, but new data indicate that Laotian Americans and Hmong Americans have even higher numbers and are more than twice as likely as other Asian Americans to die of it. Moreover, the disease tends to be diagnosed in those two groups at a late stage when it has already spread and they are less likely to receive treatment, UC Davis researchers reported Thursday. Only 3% of Laotian and Hmong Americans with liver cancer undergo surgery or liver transplantation, compared with 22% of other Asians, the researchers reported in the journal Cancer Epidemiology, Prevention and Biomarkers.
Liver cancer is much more common in the rest of the world than in the United States, but even here, 24,120 people are expected to be diagnosed with it this year and 18,910 will die, according to the National Cancer Institute. The primary cause of liver cancer is hepatitis B, which is endemic in much of Asia. The virus is frequently transmitted from mother to child during pregnancy or is contracted in childhood by contact with other children. Deaths from liver cancer in the United States are the fastest rising group of cancer deaths here, in part because the disease is so difficult to treat. The rise is due, in large part, to immigration from Asia. The rates of liver cancer are highest in male Asian Americans and Pacific Islanders, almost 12 times the rate for non-Hispanic whites. The problem is particularly severe in California, where 5 million Asian Americans account for 14% of the state's population.
Dr. Moon S. Chen Jr. and his UC Davis colleagues used data from the California Cancer Registry to identify 6,068 Californians of Asian descent who were diagnosed with hepatocellular carcinoma, the most common form of liver cancer, between 1988 and 2007. The database provided sufficient information to look individually at nine separate Asian groups: Chinese, Filipino, Vietnamese, South Asian, Korean, Japanese, Laotian/Hmong, Cambodian and Thai. The Hmong are an ethnic group from the mountainous regions of China, Vietnam, Laos and Thailand. Thousands of them were enlisted by U.S. forces during the Vietnamese war to fight Communist insurgents, and many were resettled in the United States afterward.
The researchers found that the Laotian/Hmong group were 2.08 times as likely to die of liver cancer as other Asian groups, while Cambodians were 26% more likely to do so. The median survival for Laotian/Hmong patients in the study was one month after diagnosis, compared with three months for Cambodians; four months for Thais and Filipinos; six months for Chinese, Japanese and Vietnamese; and seven months for Koreans and South Asians. Survival rates are substantially higher for whites, especially when the disease is detected early enough for surgical removal or a liver transplant. For those who receive a transplant, the five-year survival rate is 75%.
A major factor in the poor survival rate among the Hmong and Laotian Americans in that the majority are in the poorest socio-economic groups and less likely to receive care. Liver cancer, moreover, is known as a silent cancer because symptoms do not appear until it is well advanced. Screening is thus important, and most Asian Americans don't receive it, Chen said.