Cancer incidence in the Hmong in California, 1988-2000

Abstract

The Hmong represent a unique new Southeast Asian immigrant group to the U.S. Approximately 169,000 Hmong reside in the U.S., primarily in California, Minnesota, and Wisconsin. Previous studies of cancer in this population have indicated that Hmong experience an elevated risk of gastric, hepatic, cervical, and nasopharyngeal cancers and experience a reduced risk of breast, prostate, lung, and colorectal cancers. Approximately 65,000 Hmong live in California, where there has been a population-based cancer registry since 1988, and the authors used these data to calculate age-adjusted cancer incidence rates and to examine disease stage and tumor grade at diagnosis. Changes in rates during the period studied also were evaluated. These rates and proportions were compared with rates among the non-Hispanic white (NHW) and Asian/Pacific Islander (API) populations of California. Between 1988 and 2000, a total of 749 Hmong in California were diagnosed with invasive cancer, and the age-adjusted rate of cancer for the Hmong was 284 per 100,000 population, compared with 362.6 and 478 per 100,000 in the API and NHW populations, respectively. The age-adjusted incidence rates of cancer in the Hmong were elevated for hepatic, gastric, cervical, and nasopharyngeal cancers and for leukemia and non-Hodgkin lymphoma (NHL). Rates were lower in the Hmong for colorectal, lung, breast, and prostate cancers. For gastric cancer and lung cancer, age-adjusted rates increased between 1988 and 2000 in the Hmong, although breast cancer incidence declined. Cervical cancer incidence increased, rates of NHL were declining, and rates for colorectal cancer remained steady between 1988 and 2000. The Hmong experienced later disease stage at diagnosis than other API and generally poorer grade of disease at diagnosis. Hmong experienced lower overall invasive cancer incidence rates than API or NHW populations in California. However, they experienced higher rates of hepatic, gastric, cervical, and nasopharyngeal cancers; and, for most types of cancer, they were diagnosed in a later disease stage.