We thank Dr. Grant for his interest in our study (1). His comments on the potential role of vitamin D with respect to pancreatic cancer present another interesting avenue for exploring racial disparities in morbidity and mortality. The relationship between vitamin D levels and cancer was first proposed in 1980 by Garland and Garland (2). Since that time, vitamin D deficiency has been associated with increased incidence and death rates from various cancers, including those of the breast, colon, prostate, ovaries, and pancreas (3, 4).
African American race and older age are two risk factors for pancreatic cancer. Traditionally, African Americans and the elderly were most likely to suffer from vitamin D deficiency (5). National Health and Nutrition Examination Survey (NHANES) data from 1988 to 2004 show that although variation by age has equalized, it persists by race, with an increase in deficiency among African Americans (6). Thus, vitamin D could plausibly contribute to the increased incidence of pancreatic cancer among African Americans.
The questionnaire data collected at the time of enrollment into the Cancer Prevention Study II in 1982 did not measure all major sources of vitamin D intake, and blood samples were collected on only a subgroup of subjects beginning in 1999. Thus, our analyses could not examine whether lower levels of vitamin D contributed to the higher risk of pancreatic cancer mortality observed among African Americans.
In conclusion, we agree with Dr. Grant that it would be interesting to examine the role of vitamin D in racial disparities in pancreatic cancer in future studies.