A new report describes cancer among Asian Americans, Native Hawaiians, and Pacific Islanders (AANHPIs), and reports striking variation in the cancer burden within this population, reflecting vast differences in exposure to cancer risk factors.

Lung cancer rates in Samoan men (98.9 per 100,000) are about 30% higher than those in Hawaiian (72.1), non-Hispanic white (NHW) (71.2), and Laotian (65.2) men and almost 80% higher than in Asian Indian/Pakistani men (21.1) because of differences in smoking.

For liver cancer, another highly fatal cancer, rates in Laotian (66.1 per 100,000) and Vietnamese (51.9) men are 2 to 4 times higher than those in Chinese (21.7), Koreans (26), and Filipinos (16.7) and almost 10 times higher than Asian Indians and Pakistanis (6.5), who have the lowest rates.

The report, appearing in CA: A Cancer Journal for Clinicians and as the Special Section in Cancer Facts & Figures 2016, estimates there will be 57,740 new cancer cases and 16,910 cancer deaths among AANHPIs in 2016.

The three leading causes of cancer death among AANHPI males combined are lung (27%), liver (14%), and colon/rectum (11%).

Among women, they are lung (21%), breast (14%), and colon/rectum (11%).

The term Asian refers to a person with origins in the Far East, Southeast Asia, or the Indian subcontinent.

This group includes, but is not limited to, Asian Indians, Cambodians, Chinese, Filipinos, Hmong, Japanese, Koreans, Pakistanis, and Vietnamese.

Asian Americans represented 6.3% of the total US population in 2014 and are the fastest growing racial/ethnic group in the United States.

In contrast to Hispanics, the rapid growth in the Asian American population is driven by immigration as opposed to native births.

The term "Native Hawaiian and Pacific Islander" (NHPI) refers to people with origins in Hawaii, Guam, Samoa, or other Pacific Islands.

The NHPI population is also one of the fastest-growing populations in the United States.

Cancer rates in this group are generally higher than those in Asian Americans.

AANHPIs are composed of diverse populations with different origins, histories, and cultures.

While Asian and NHPI origins have been recognized as distinct racial groups in the US Census since 2000, demographic and health data for these two groups are usually combined because of small numbers or for continuity with historical statistics.

This aggregate reporting of AANHPI cancer data masks important differences between the heterogeneous AANHPI populations.

The largest Asian American subpopulation in the United States is Chinese (23%), followed by Filipino (20%), Asian Indian (18%), Vietnamese (10%), and Korean (10%).

The largest NHPI subpopulation is Native Hawaiian (43%), followed by Samoan (15%), Guamanian or Chamorro (12%), and Tongan (5%).

Ten US states are home to 73% of the AANHPI population; California has the largest proportion with 32% followed by New York (9%), Texas (7%), Hawaii (5%), and New Jersey (5%).

The new report relies on data from the National Cancer Institute, the Centers for Disease Control and Prevention, the North American Association of Central Cancer Registries, and the National Center for Health Statistics.

Key findings from the report include:

• Among males, overall incidence rates (per 100,000 during 2006 to 2010) range from 216.8 among Asian Indians/Pakistanis to 526.5 among Samoans, whose rates are similar to rates in NHWs (554.1). Among females, rates range from 212.0 among Asian Indians/Pakistanis to 442.8 among Samoans, also similar to rates in NHWs (444.6). For both males and females, the highest rates after Samoans were among Native Hawaiians and Japanese.
• Age-standardized breast cancer incidence rates in AANHPIs range from 35.0 per 100,000 in Cambodian women to 135.9 in Hawaiian women, likely reflecting differences in reproductive patterns, as well as mammography utilization.
• Lung cancer rates among Chinese women (in both Asia and the U.S.) are relatively high given the low prevalence of smoking in this group. Reasons are unknown but may include exposure to cooking oils at high heat, secondhand smoke, genetic susceptibility, or other unknown risk factors
• AANHPIs are less likely than NHWs to be diagnosed with cancer at a localized stage. The largest absolute differences are for cancers of the thyroid (9%), cervix (8%) prostate (5%), and lung (3%). The disparities for cervical and thyroid cancers may be attributable to less access to health care among AANHPIs, including screening and diagnostic services.
• Cancer death rates, which are not available by subgroup, have been decreasing since 1992 in AANHPIs as a whole, mirroring trends in NHWs.
• Breast cancer mortality rates decreased by 16% among AANHPI women combined from 1990 to 2012. These reductions have been attributed to improvements in both treatment and early detection.
• Liver cancer death rates declined among AANHPI males from 2003 to 2012 and were stable among AANHPI females, in contrast to dramatic increases in non-Hispanic whites.
• Utilisation of the Pap test within the past 3 years is highest among Filipino women (83%, the same rate as in NHWs), and lowest among Chinese women (66%).
• Cervical cancer incidence rates among Cambodian, Vietnamese, and Laotian women decreased dramatically from 1990 to 2008, a change that has been attributed to increases in screening and treatment of precancerous lesions in these groups.
• The proportion of women 45 years of age or older who report having a mammogram within the past 2 years is similar among the Asian groups for whom data are available, ranging from 68% in Filipino women - comparable to NHWs (69%) - to 64% in Asian Indians.
• Colorectal cancer screening in the largest Asian groups is slightly lower than that in NHWs (61%) - 54% in Asian Indians and Chinese and 59% in Filipinos - although it is substantially lower in all other Asian groups combined (46%), which includes Koreans, Japanese, and Vietnamese.

"The variations we see in cancer rates in AANHPIs are related to risk factors, including lifestyle factors, use of screening and preventive services, and exposure to cancer-causing infections," said Lindsey Torre, co-author of the report.

"Cancer-control strategies among this population include improved use of vaccination and screening; interventions to increase physical activity and reduce excess body weight, tobacco use, and alcohol consumption; and research to get a more detailed understanding of differences in the cancer burden and risk factors between subgroups."

Source: American Cancer Society