Normal and neoplastic cells respond to genome integrity threats in a variety of different ways. Furthermore, the nature of these responses are critical both for cancer pathogenesis and for cancer treatment. DNA damaging agents activate several signal transduction pathways in damaged cells which trigger cell fate decisions such as proliferation, genomic repair, differentiation, and cell death. For normal cells, failure of a DNA damaging agent (i.e., a carcinogen) to activate processes culminating in DNA repair or in cell death might promote neoplastic transformation. For cancer cells, failure of a DNA damaging agent (i.e., an antineoplastic drug) to promote differentiation or cell death might undermine cancer treatment. Our laboratory has discovered the most common known somatic genome alteration in human prostatic carcinoma cells. The DNA lesion, hypermethylation of deoxycytidine nucleotides in the promoter of a carcinogen-defense enzyme gene, appears to result in inactivation of the gene and a resultant increased vulnerability of prostatic cells to carcinogens. Studies underway in the laboratory have been directed at characterizing the genomic abnormality further, and at developing methods to restore expression of epigenetically silenced genes and/or to augment expression of other carcinogen-defense enzymes in prostate cells as prostate cancer prevention strategies. Another major interest pursued in the laboratory is the role of chronic or recurrent inflammation as a cause of prostate cancer. Genetic studies of familial prostate cancer have identified defects in genes regulating host inflammatory responses to infections. A newly described prostate lesion, proliferative inflammatory atrophy (PIA), appears to be an early prostate cancer precursor. Current experimental approaches feature induction of chronic prostate inflammation in laboratory mice and rats, and monitoring the consequences on the development of PIA and prostate cancer.