Cancer cells display characteristics that are acquired at different times of cancer development and with various strategies. Genomic instability and/or epigenetic changes are thought to initiate the carcinogenic processes. Thus, molecular classification of cancer may include either gene-expression profiles, chromosomal aberrations and cancer genome sequencing, or epigenetic changes such as microRNA aberrations, DNA methylation, and telomere changes. The aim of this study is the detection of molecular signatures of cancer related to specific exposure. Biological monitoring of exposures to carcinogens includes a variety of biomarkers, but the entire chain of events from exposure to disease has never been demonstrated. Genome-wide studies indicating associations between disease and single nucleotide polymorphism could define a way of selecting individuals for prospective biomonitoring. Exploring and understanding the pathways controlled by genes thought to be involved in carcinogenesis will likely pave the way in improving the molecular classification of cancer and in choosing the most appropriate endpoints to be used in biological monitoring.