Racial flip seen in pancreatic cancer mortality
Pancreatic cancer mortality has diverged in race-defined directions, increasing in whites and decreasing in blacks for reasons that remain unclear, investigators reported.
After 25 years of decline, pancreatic cancer mortality in whites has been on the increase since the mid- to-late 1990s, whereas mortality among blacks has declined steadily since the early 1990s after 20 to 25 years of increases.
Age-period-cohort analysis showed statistically significant increases in pancreatic cancer mortality in white men and women since the late 1990s.
"The decreasing trend in blacks over the past 10 to 15 years is particularly interesting because the prevalence rates of factors ... that are likely contributing to the recent increases in pancreatic cancer death rates in whites have also increased in blacks," Jiemin Ma, PhD, of Brigham and Women's Hospital in Boston (formerly of the American Cancer Society), and co-authors concluded in an article published online in the Journal of the National Cancer Institute.
"With a full manifestation of the consequences of a fairly new obesity epidemic, pancreatic cancer could become a major public health problem in the future in the United States if no urgent interventions are to take effect."
Despite intense laboratory and clinical investigation, pancreatic cancer remains one of the major causes of cancer death in the United States, ranking fourth overall. Men and women alike are affected to a similar extent.
Part of the lack of progress toward improving mortality in pancreatic cancer can be traced to a continued lack of understanding about the disease's etiology. Smoking and obesity are modifiable risk factors with the best supporting evidence. Numerous other lifestyle factors have been implicated but have modest supporting data at best.
Examination of long-term disease trends could provide clues to the origin of pancreatic cancer. However, few studies have focused on trends in pancreatic cancer, the authors noted in their introduction. In particular, no studies have evaluated recent trends using age-period-cohort analysis, which might be more informative than conventional cross-sectional analysis.
"Period effects are usually generated by factors that affect all ages concurrently, such as improvements in diagnostic practice and treatment," Ma and colleagues said. "In contrast, cohort effects are attributed to risk factors that vary in prevalence by generation, such as smoking."
To examine recent trends in pancreatic cancer mortality, investigators searched the National Cancer Institute Surveillance, Epidemiology and End Results database for 1970 to 2009. They identified all cases wherein pancreatic cancer was designated as the underling cause of death.
The overall analysis showed that pancreatic cancer mortality decreased in white men by 0.7% per year from 1970 to 1995 and then increased by 0.4% annually through 2009. White women had a small increase in pancreatic cancer mortality from 1970 to 1984, followed by a period of stabilization and then an increase of about 0.5% per year since the late 1990s.
Analysis of slope change showed that the rise in pancreatic cancer mortality in whites achieved statistical significance in men and women (P<0.001).
Among blacks, pancreatic cancer mortality increased from 1970 to the late 1980s in women and to the early 1990s in men. Since then, mortality from pancreatic cancer has declined steadily in both sexes.
Decreased smoking prevalence has been recognized as a contributing factor in pancreatic cancer mortality decreases. However, the decline in smoking started about 1965 in whites and blacks. The reason for the delayed impact in blacks is unclear, the authors said.
Age-period-cohort analysis showed that pancreatic CA mortality was highest for men from the birth cohort of 1900 to 1910 and for women from the 1920 to 1930 birth cohort. The increase since the late 1990s in white men and women was statistically significant (P<0.001).
Black and white women from the birth cohort of 1950 to 1960 also had significant increases in pancreatic cancer mortality (P=0.023, P=0.017, respectively).
"Because of lack of reliable long-term data, it is difficult to evaluate the potential influence of some suspected risk factors ... on pancreatic cancer trends," the authors said in their discussion of the findings. "However, it is highly likely that these suspected and some unknown risk factors may have modified the effects of known risk factors on pancreatic cancer trends."
"Because there have been few improvements in pancreatic cancer survival over the last three decades, treatment would have had limited impact on pancreatic cancer death trends."
The findings highlight a "looming crisis of rising pancreatic cancer death rates in the United States," Dana B. Cardin, MD, and Jordan D. Berlin, MD, of Vanderbilt University in Nashville, Tenn., said in an accompanying editorial. "To answer this concern, the NCI has prioritized pancreatic cancer research. However, the funding available to the NCI continues to decline in the face of sequestration and a government focused on partisan bickering and political showmanship."
"Our country needs to act now, or we will simply be spectators as thousands more people die each year from this devastating illness."
Source: MedPage Today: http://www.medpagetoday.com/HematologyOncology/OtherCancers/42925