Particulate matter air pollution and liver cancer survival

Abstract

Particulate air pollution (PM) exposure has been associated with cancer incidence and mortality especially with lung cancer. The liver is another organ possibly affected by PM due to its role in detoxifying xenobiotics absorbed from PM. Various studies have investigated the mechanistic pathways between inhaled pollutants and liver damage, cancer incidence, and tumor progression. However, little is known about the effects of PM on liver cancer survival. 20,221 California Cancer Registry patients with hepatocellular carcinoma (HCC) diagnosed between 2000–2009 were used to examine the effect of exposure to ambient PM with diameter less than 2.5µm (PM2.5) on HCC survival. Cox proportional hazards models were used to estimate hazard ratios (HRs) relating PM2.5 to all-cause and liver cancer-specific mortality linearly and non-linearly— overall and stratified by stage at diagnosis (local, regional, and distant)—adjusting for potential individual and geospatial confounders. PM2.5 exposure after diagnosis was statistically significantly associated with HCC survival. After adjustment for potential confounders, the all-cause mortality HR associated with a 1 standard deviation (5.0 µg/m3) increase in PM2.5 was 1.18 (95% CI: 1.16 – 1.20); 1.31 (95% CI:1.26 – 1.35) for local stage, 1.19 (95% CI:1.14 – 1.23) for regional stage, and 1.05 (95% CI:1.01 – 1.10) for distant stage. These associations were nonlinear, with substantially larger HRs at higher exposures. The associations between liver cancer-specific mortality and PM2.5 were slightly attenuated compared to all-cause mortality, but with the same patterns. Exposure to elevated PM2.5 after the diagnosis of HCC may shorten survival, with larger effects at higher concentrations.

Long-Term Exposure to Air Pollutants and Cancer Mortality: A Meta-Analysis of Cohort Studies

“…Finally, the full texts of the remaining 105 articles were inspected, of which 75 articles were excluded for the following reasons: no RR data (n = 31), air pollution not quantified (n = 14), insufficient exposure and outcome data (n = 8), a categorical range of air pollutants was used (n = 8), population sharing (n = 7), no mortality rates for cancer (n = 5), cancer incidence was used as an outcome measurement (n = 1), and smoking status was used as a co-exposure factor (n = 1). The remaining 30 cohort studies were included in the meta-analysis [ 7 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 ]. All cohort studies were prospective except the study by Ancona et al [ 35 ], which was retrospective.…”

Association between Post-Diagnosis Particulate Matter Exposure among 5-Year Cancer Survivors and Cardiovascular Disease Risk in Three Metropolitan Areas from South Korea

“…Exposure to PM affects short-term survival of patients with lung and liver cancers [18,19], as well as long-term survival of patients with breast cancer [20]. Although former investigators speculated that PM affects cancer progression and leads to poor outcomes, cardiovascular morbidity and mortality due to PM has not yet been studied among cancer survivors.…”

EASL Clinical Practice Guideline: Occupational liver diseases

“…Unpredictable routes of exposure such as breakdown, cleaning and maintenance of machinery, and accidental leakage still occur though and new causes of OLD will potentially come to light, such as liver silicosis, particulate matter air pollution and increasing use of nanomaterials. [1][2][3] Moreover, the diagnosis of OLD remains challenging in clinical practice due to the lack of pathognomonic signs and sensitive biomarkers of liver injury. Whilst acknowledging that viral infections in hospital workers are recognised as OLDs, herein, attention will only be paid to chemically induced liver injuries.…”