Mortality rates from cancer among American Indian and Alaska Native (AIAN) patients are 18% higher than for White patients despite similar rates of cancer incidence overall, new research shows.
For the most common cancer types — breast, prostate, and lung cancer and colorectal cancer (CRC) — the data show that AIAN individuals have mortality rates that are 8%-42% higher than those in White individuals, despite a lower incidence for some of these cancers and the availability of early detection tests for all of them, the authors point out.
“Cancer disparities in this population parallel those for other chronic diseases caused by long-standing inequities in SES (socioeconomic status), education and access to care,” lead author Tyler Kratzer, MPH, from the American Cancer Society, Kennesaw, Georgia, and colleagues commented.
Some 2.6 million AIAN individuals receive healthcare at Indian Health Service or tribal healthcare facilities, which are chronically underfunded; as a result, many facilities do not offer cancer screening services.
“Improving screening access for rural AIAN populations is a necessary component of reducing cancer disparities,” the authors conclude.
The findings were published online November 8, 2022, in CA: A Cancer Journal for Clinicians.
For this study, Kratzer and colleagues analyzed incidence and mortality rates for various cancer types between 2014 and 2018, using population-based data from the National Cancer Institute, the Centers for Disease Control and Prevention, and the North American Association of Central Cancer Registries.
The team found large disparities in the incidence of and mortality from cancer by both cancer type and geographic region.
For instance, among AIAN individuals who lived in Purchased/Referred Care Delivery Area regions, the cancer incidence was only 2% higher than in White persons.
However, for all AIAN individuals overall, the incidence rates of liver cancer, stomach cancer, and kidney cancer were approximately twice as high as those in White patients, whereas rates of uterine/cervical cancer and CRC were about 50% higher in AIAN patients compared with White patients.
“In contrast, rates of breast and prostate cancer were 12% and 15% lower, respectively, among AIAN individuals than among White Individuals,” the authors note.
In general, cancer is diagnosed at a later stage in AIAN patients, the authors note. As a result, 5-year relative survival rates are lower among this group than among White patients for most cancer types.
For example, 75% of AIAN patients were diagnosed with advanced or unstaged stomach cancer vs 69% of White patients, whereas the 5-year relative survival rate from stomach cancer through 2011 and 2017 was 19% for AIAN patients compared with 32% for their White counterparts.
For all sites combined, mortality from cancer was 18% higher among AIAN patients than among White patients, the largest disparities between the two groups being for stomach, liver, and uterine/cervical cancer.
On the other hand, mortality rates have been declining since at least 1997 in AIAN men and since 2006 in AIAN women, with the exceptions of liver and pancreatic cancer.
“Like incidence [rates], mortality rates vary widely geographically,” the researchers emphasize.
Breast cancer is still the most commonly diagnosed cancer in AIAN women, even though the incidence was 12% lower among AIAN women than among White women.
This is not true for CRC incidence rates, which were 43% higher in AIAN patients than they were in White patients. In fact, Alaska Natives have the highest reported incidence and mortality rates from CRC in the world, the authors note.
Mortality rates from CRC were equally high, probably a reflection of the fact that AIAN patients were less likely than White patients to be diagnosed with localized CRC.
The authors note that fewer AIAN patients were up to date for CRC screening compared with White patients; as a result, mortality rates among AIAN men decreased at one-half the pace of the decrease seen among White men, although rates among AIAN women remained stable during the same time period.
Importantly as well, the incidence of early-onset CRC in patients between 20 and 49 years of age increased twice as fast among AIAN patients than it did among White patients, as did mortality rates. AIAN patients also had a 79% higher incidence of kidney cancer compared with White patients, whereas mortality rates ran right behind incidence rates at 77%.
The incidence of liver cancer was also high — in fact higher than in any other major racial/ethnic group in the US — whereas mortality rates from liver cancer were over twice as high in AIAN patients than in White patients. Mortality rates from liver cancer also increased steadily by 2% per year from 1997 to 2019; in contrast, they have stabilized among White patients, at least in more recent years.
In men and women combined, lung cancer is the most common cancer diagnosed in AIAN patients; mortality rates from this disease were 12% higher in this ethnic group than in White patients. As Kratzer and colleagues note, lung cancer incidence rates have been declining in the general population since the 1990s in men and since the mid-2000s in women, whereas they only began to decline in 2014 in AIAN men and continue to remain stable in women. About 25% of AIAN adults are current smokers, which is a higher smoking rate than in any other major racial or ethnic group in the US, they point out.
The incidence of pancreatic cancer, in turn, was also 9% higher among AIAN patients than in White patients, but the disparity in mortality from pancreatic cancer was minimal between the two groups, given that pancreatic cancer in both groups is usually diagnosed at an advanced stage. Mortality rates between the two groups from pancreatic cancer were comparable.
Kratzer reports no conflicts of interest. One co-author reports personal fees from the Northwest Portland Indian Health Board outside the submitted work and is a fiduciary officer of the International Association of Cancer Registries. The remaining authors made no disclosures.
CA: A Cancer Journal for Clinicians. Published online November 8, 2022.