Alhamdow A, et al. - Among non-smoking males from Sweden, including 118 chimney sweeps and 126 occupationally unexposed controls, researchers assessed the links between polycyclic aromatic hydrocarbons (PAH) exposure and serum levels of cancer-related proteins. They used LC/MS/MS to assess monoydroxylated metabolites of pyrene, phenanthrene, benzo[a]pyrene, and benzo[a]anthracene in urine and used a Proximity Extension Assay to assess 90 cancer-related proteins in serum. They found 17 serum proteins with differential expression (16 upregulated and 1 downregulated) in chimney sweeps vs controls in linear regression analysis adjusted for age, BMI, and false discovery rate (FDR). Significant positive links with urinary concentrations of the PAH metabolites 3-hydroxybenzo[a]pyrene and 3-hydroxybenzo[a]anthracene were shown by peptidase kallikrein 13 (KLK13) levels. Dose-response links were observed between KLK13 and 3-hydroxybenzo[a]pyrene and 3-hydroxybenzo[a]anthracene. Ultimately, in workers exposed to PAH, proteins reputed to be related to cancer were differentially expressed.