Impact of Antioxidant Betacarotenoid on Lung and Colorectal
Cancer Mortality: An 18 Year Followup Study of A National Cohort
Daneisha Hawkins, BS; Dr. Evans Afriyie-Gyawu, PhD, MPH; and Dr.
Jian Zhang, MD, DrPH
Department of Epidemiology and Environmental Health Sciences,
Georgia Southern University
Introduction
• β-carotenoids, precursors of vitamin A, are important
antioxidants within the physiological system in humans
and animals
Figure 1. Chemical structure of beta-carotene
• Consumption of antioxidants containing fruits and
vegetables is a part of overall healthy lifestyle
Figure 2: Examples of foods rich in β-carotene
Introduction continued…
• Lung cancer has been described to be the leading cause
of cancer-related deaths in the U.S., followed by
colorectal cancer (CDC, 2016)
• Decreased carotenoid levels are known to be directly
associated with elevated markers of inflammation and
oxidative stress
• Protective effects of β-carotenoids on individuals
without cancer has been established; however, this effect
has not been fully characterized among cancer patients
Objective & Hypothesis
• Objective: Examine the influence of serum β-carotenoid
levels on lung and colorectal cancer mortality
• Hypothesis: Adequate physiological levels of serum βcarotenoid reduce lung and colorectal cancer mortality
Methods
•
Study population: data were obtained from the NHANES III
study using a multistage probability sampling of the
noninstitutionalized US population (1988-1994)
•
A retrospective cohort study conducted with 14,358 adults (19
years or older) who participated in phase II of the National Health
and Nutrition Examination Survey III (1991-1994) (NHANES III)
•
Data were collected via in-home interviews and visits by
participants to a mobile examination center for blood sample
collection
Methods Continued…
•
Covariates such as family income, educational attainment, marital
status, race/ethnicity, alcohol consumption, cigarette smoking,
self-reported health status, body size, cancer status at baseline,
vegetable/fruit/juice consumption were examined
•
Serum samples were collected from study participants for the
analysis. This served as baseline and was correlated with the
National Death Index database between 1991-2006
•
Hazard ratio (HR) estimates for all-cause and cancer-related
deaths among individuals with different serum β-carotenoid
levels were obtained from Cox Proportional Hazards Regression
Results (Tables & Figures)
Table 1. Adjusted vs. Unadjusted Hazard Ratio of Deaths Associated with Low Levels of
Serum β-carotenoid (25% as cutoff) 14358 Adults2, NHANES III Follow-up Study 1988-2006
1
2
1Adjusted
for age and sex
for age, sex, race, family income, educational attainment,
alcohol consumption, cigarette smoking
2Adjusted
Results (Tables & Figures)
Table 2. Adjusted Hazard Ratio of Death Caused for ß-carotenoid
Using 3-Level Categorization 1
1Adjusted
for age, sex, race, family income, educational
attainment, alcohol consumption, cigarette smoking
Results (Tables & Figures) cont’d…
a) BCP3CAT and Lung Cancer Deaths (n=765)
b) BCP3CAT and Colorectal Cancer Deaths (n=79)
Blue = low levels of ß-Carotenoid,
Red = high levels
Green = moderate levels
Fig 3: Survival functions of adults by the serum level of CAR3CAT, NHANES III follow-up, 1988-2006
Discussion
•
Lung cancer is the leading type of cancer for men and women in
the U.S, and colorectal cancer is third for both men and women in
the U.S
•
Results from this nationally representative study indicate that low
serum ß-carotenoid levels are significantly associated with
increased lung cancer mortality
•
Association between high levels of serum ß-carotenoid and
reduced risk of lung cancer mortality is biologically plausible
•
Decreased carotenoid levels is associated with an elevation of
inflammatory markers and oxidative stress which can enhance
mortality among lung cancer patients
Strengths & Limitations
Strengths:
• To our knowledge, this is the first nationally representative study on U.S.
population to examine the link between serum β-carotenoid and lung /
colorectal cancer mortality.
• Due to the large sample size of this study, we were able to obtain informative
risk estimates (Hazard Ratios) even when the data were adjusted for multiple
covariates (potential confounders).
• We selected study participants from the community (extending beyond
clinical populations) to achieve a true representation.
Limitations:
• Data do not include the elderly in institutionalized facilities.
• Serum β-carotenoid level was measured only once during the study
Conclusions
• Our results indicate that low serum ß-carotenoid levels are
significantly associated with risk of lung cancer mortality
• Findings from this study can be utilized to conduct further research
on the effect(s) or benefits of carotenoids with respect to lung cancer
mortality and determine optimum dose for intervention purposes
• It is essential to examine the effect(s) of the micronutrient ßcarotenoid on sensitive populations such as pregnant women,
HIV/AIDS and other immunocompromised individuals
Conclusions continued…
•
Public health officials may eventually use this information to
increase fruit and vegetable consumption in order to reduce the
risks associated with lung cancer mortality
•
Further research is warranted to determine the mechanism by
which optimum serum ß-carotenoid levels could extend survival
among lung cancer patients
References
• Bouayed, J., & Bohn, T. (2010). Exogenous antioxidants—doubleedged swords in cellular redox state: health beneficial effects at
physiologic doses versus deleterious effects at high doses. Oxidative
medicine and cellular longevity, 3(4), 228-237.
• CDC (2016). Colorectal Cancer Trends. Retrieved
https://www.cdc.gov/cancer/colorectal/statistics/trends.htm
• CDC (2016b). Lung Cancer Trends. Retrieved from
https://www.cdc.gov/cancer/lung/statistics/trends.htm
• Grune, T., Lietz, G., Palou, A., Ross, A. C., Stahl, W., Tang, G., ... &
Biesalski, H. K. (2010). β-Carotene is an important vitamin A source
for humans. The J of Nutr, 140(12), 2268S-2285S.