The invention relates generally to methods for determining the likelihood that targeted somatic mutagenesis of a nucleic acid molecule by a mutagenic agent has occurred, and the likelihood that a mutagenic agent is a cause of targeted somatic mutagenesis of a nucleic acid molecule. The invention further relates to methods for diagnosing cancer in a subject and/or determining the likelihood that a subject has or will develop cancer, and methods for treating subjects diagnosed with cancer or determined to be likely to have or to develop cancer. In further aspects, the invention relates to methods for identifying motifs in nucleic acid molecules that are recognized or targeted by mutagenic agents.
