Native Hawaiians had a 71% increased risk for pancreatic cancer compared with White individuals, even after adjusting for known risk factors, found a study based on long-term follow-up data from approximately 80,000 individuals.
Previous studies have shown disproportionate risk for pancreatic cancer in different racial and ethnic groups, notably Native Hawaiians, but data on the risk factors driving this disparity are lacking, Brian Z. Huang, PhD, MPH, a cancer epidemiologist and assistant professor at the Keck School of Medicine at the University of Southern California, Los Angeles, and colleagues wrote.
The researchers reviewed pancreatic cancer incidence and risk factors among 13,641 Native Hawaiians and 47,240 White adults who were part of the Multiethnic Cohort Study, an epidemiological study of more than 200,000 native Hawaiian and White individuals in Hawaii and Los Angeles.
Incidence pancreatic cancer rates per 100,000 person-years were almost double for Native Hawaiians compared with White individuals (80.2 vs 44.6) over an average follow-up period of 20.3 years, found the study, published online in the American Journal of Gastroenterology.
After adjusting for five established risk factors (diabetes, obesity, smoking, alcohol consumption, and family history of pancreatic cancer), Native Hawaiians overall had a higher risk for pancreatic cancer than White individuals (hazard ratio [HR], 1.71). Risks were elevated for Native Hawaiian men and women (HR, 1.54 and 1.85, respectively) compared with their White counterparts.
The risk for pancreatic cancer was elevated for Native Hawaiians relative to White individuals with the same specific risk factors, with HRs ranging from 1.5 to 2.27. The increased risk for Native Hawaiian men compared with White men was more pronounced among those with diabetes (HR, 3.1) than among those without diabetes (HR, 1.35).
The pancreatic cancer risk among Native Hawaiians increased with the number of risk factors. Native Hawaiians with zero, one, or two or more risk factors had 1.75, 1.90, and 3.69 times the risk, respectively, compared with White individuals with no risk factors. The association was greater in men than in women. Native Hawaiian men with two or more risk factors had more than five times the risk compared with White individuals (HR, 5.17), while Native Hawaiian women with two or more risk factors had approximately twice the risk (HR, 2.18).
Looking at specific risk factor profiles, Native Hawaiians with diabetes, obesity, and smoking had 3.41, 2.35, and 2.62 times the risk for pancreatic cancer, compared with White individuals with no risk factors.
Native Hawaiians with both diabetes and obesity had 3.69 times the risk for pancreatic cancer, whereas Native Hawaiians with both smoking and obesity had 2.99 times the risk compared with White individuals with no risk factors.
"We observed that the elevated pancreatic cancer risk for Native Hawaiians may largely stem from the higher prevalence of diabetes and/or the higher total number of risk factors within this population," the researchers wrote. "Notably, the cumulative effect of multiple risk factors is more evident among males than females; thus, Native Hawaiian males with multiple risk factors may represent a high-risk group that could benefit from targeted pancreatic cancer screening efforts."
Genetics also may play a role. In a subset of 19,542 study participants for whom genetic data were available, Native Hawaiians had an increased risk for pancreatic cancer compared with White individuals across high and low levels of polygenic risk scores for intra-pancreatic fat deposition and for pancreatic cancer.
"Future research is warranted to investigate other potential risk factors and biological or environmental mechanisms driving pancreatic cancer disparities among Native Hawaiians and other racial and ethnic minority populations," the researchers wrote.
The study findings were limited by the use of self-reports of lifestyle risk factors and the assessment of them only at baseline, which did not account for any behavior changes over time, the researchers noted. However, the results were strengthened by the large study population and prospective design, they said.
The study is "an important step toward identifying high-risk patients to develop more effective ways of screening for pancreatic cancer," Nicholas DeVito, MD, assistant professor at Duke University Medical Center, Durham, North Carolina, and a specialist in gastrointestinal malignancies, told Medscape Medical News.
"The effect size, meaning the increase in patients with pancreatic cancer, was particularly striking in male native Hawaiians with risk factors," said DeVito, who was not involved in the study. "These risk factors were not nearly as profoundly impactful in the White population, implying that there is an underlying genetic risk that makes Native Hawaiians more prone to pancreatic cancer when known risk factors are present."
Based on the study findings, "I would strongly recommend that all native Hawaiians reduce their risk factors to the best of their ability with the knowledge that it is more impactful on their pancreatic cancer chances than the same risk factors are in white populations," DeVito said. "This is especially true of males, and if they are concerned, they should speak to their doctor about pancreatic cancer screening."
Looking ahead, large-scale genetic and lifestyle studies that follow patients from multi-ethnic cohorts over their lifetime will be important, DeVito said. Such research could help determine the actual mechanisms of increased risk, namely what environmental or other risk factors are driving the dramatic increase in pancreatic cancer risk in this specific population, he said.