It is generally accepted that cancer is a genetic disease resulting from the accumulation of multiple genomic rearrangements. These rearrangements involve gross chromosomal abnormalities (e.g. translocations and deletions) as well as submicroscopic mutations affecting both oncogenes and tumour suppressor genes. Recent studies of several tumour specific translocations in sarcomas have shown that the translocations result in so-called fusion genes. In this review we will discuss the specificity and implications of different genetic alterations in both sporadic and hereditary human solid tumours, and provide examples of how these changes can be used as tumour specific markers of both diagnostic and prognostic significance.