Ambient ultraviolet radiation exposure and hepatocellular carcinoma incidence in the United States

Abstract

BackgroundHepatocellular carcinoma (HCC), the most commonly occurring type of primary liver cancer, has been increasing in incidence worldwide. Vitamin D, acquired from sunlight exposure, diet, and dietary supplements, has been hypothesized to impact hepatocarcinogenesis. However, previous epidemiologic studies examining the associations between dietary and serum vitamin D reported mixed results. The purpose of this study was to examine the association between ambient ultraviolet (UV) radiation exposure and HCC risk in the U.S.MethodsThe Surveillance, Epidemiology, and End Results (SEER) database provided information on HCC cases diagnosed between 2000 and 2014 from 16 population-based cancer registries across the U.S. Ambient UV exposure was estimated by linking the SEER county with a spatiotemporal UV exposure model using a geographic information system. Poisson regression with robust variance estimation was used to calculate incidence rate ratios (IRRs) and 95% confidence intervals (CIs) for the association between ambient UV exposure per interquartile range (IQR) increase (32.4 mW/m2) and HCC risk adjusting for age at diagnosis, sex, race, year of diagnosis, SEER registry, and county-level information on prevalence of health conditions, lifestyle, socioeconomic, and environmental factors.ResultsHigher levels of ambient UV exposure were associated with statistically significant lower HCC risk (n = 56,245 cases; adjusted IRR per IQR increase: 0.83, 95% CI 0.77, 0.90; p < 0.01). A statistically significant inverse association between ambient UV and HCC risk was observed among males (p for interaction = 0.01) and whites (p for interaction = 0.01).ConclusionsHigher ambient UV exposure was associated with a decreased risk of HCC in the U.S. UV exposure may be a potential modifiable risk factor for HCC that should be explored in future research.Electronic supplementary materialThe online version of this article (doi:10.1186/s12940-017-0299-0) contains supplementary material, which is available to authorized users.

A Review of the Evidence Supporting the Vitamin D-Cancer Prevention Hypothesis in 2017

“…According to U.S.Α. ecological studies conducted using cancer incidence rates after 1999, UV doses significantly inversely correlated with 14 cancers: bladder, brain, breast, colon, endometrial, hepatocellular carcinoma, lung, ovarian, pancreas, pleura, prostate, rectal, and thyroid cancer as well as non-Hodgkin's lymphoma (mainly diffuse large B-cell lymphoma) (12,14,22,24). For cancer mortality rates, inverse correlations were evident only for bladder, endometrial, esophageal, lung, and ovarian cancer as well as leukemia and non-Hodgkin's lymphoma (12).…”

Changing trends in the disease burden of primary liver cancer caused by specific etiologies in China

“…The major risk factors for primary liver cancer that have been identified can be categorized into three groups 6 : (a) established factors, including infection with HBV or HCV, alcohol consumption, dietary aflatoxins, NAFLD, NASH, 25 and smoking 26 ; (b) likely factors, including diabetes mellitus, inherited metabolic disorders, hemochromatosis, porphyria cutanea tarda, and cirrhosis of any etiology; and (c) possible factors, such as low vegetable intake, 27 oral contraceptive use, 28 and radiation exposure. 29 Chronic HBV infection in China has been considered to be the most common factor in the etiology of liver cancer and a major contributor to its development. 30 Our study showed that the proportion of liver cancer caused by hepatitis B was approximately 60%, which is significantly lower than previous reports.…”

Ambient PM2.5 air pollution exposure and hepatocellular carcinoma incidence in the United States

“…In this analysis, the strongest confounders were population density, socioeconomic factors, and UV, which have been associated with liver cancer. Higher population density has been associated with increased liver cancer risk, and higher socioeconomic status and UV and vitamin D levels have been associated with decreased liver cancer risk [32, 56, 65, 66]. PM 2.5 concentrations are higher in areas with higher population density, related to sources of PM 2.5 including combustion from motor vehicles and other anthropogenic sources [12].…”

“…The following criteria were used to define HCC cases: International Classification of Diseases for Oncology, Third Edition (ICD-O-3) topography code C22.0 for primary liver cancer and ICD-O-3 histology codes 8170 to 8175 [27]; diagnostic confirmation (e.g., positive histology) excluding clinical diagnosis only [28]; sequence number of one primary only; diagnosis between 2000 and 2014; and not reported via autopsy or death certificate only [29]. As conducted in previous SEER-based epidemiologic studies, counts of HCC cases were stratified by age at diagnosis (<65 years, ≥65); sex (male, female); race (white, black, Asian/Pacific Islander/American Indian/Alaska Native); and year of diagnosis (2000–2007, 2008–2014) for each county [30–32]. Each county was associated with one SEER registry.…”