Towards a New Generation of Tumour Markers

Tumour markers, measured in the serum, have been used in clinical practice for many years. However, it is probably fair to say that major clinical decisions are seldom made on the basis of tumour markers alone. Thus, in contrast to imaging techniques, the role of tumour markers in our clinical armamentarium has been relatively small. The reason is clear. With few exceptions, the sensitivity and specificity have been relatively low, and we have developed a preference for tumour assessment in terms of its 'physical' size rather than on any biochemical basis. Nonetheless, it is true that, in a few notable instances, markers have had a clinical impact, and the more successful ones have taught us how to use them and the concepts of sensitivity and specificity have now become widely understood.

To progress further, however, we need new sources of specificity, that is, new ways of differentiating between the products of tumour cells and their normal counterparts. Recent advances in our understanding of the molecular biology of cancer, together with new ways of detecting and analysing minute amounts of nucleic acids (particularly polymerase chain reaction [PCR] -based techniques) now offer us the opportunity to achieve such progress.

Such advances were brought together in a recent symposium, Circulating Nucleic Acids in Plasma and Serum -II, held in Hong Kong in March of this year. Researchers from around the world focused on the medical uses of the detection of free nucleic acids, either DNA or RNA, in serum or plasma and, in this issue, we report some of the applications related to cancer. The fact that it is now clearly possible to detect specific genetic changes, characteristic of a particular tumour, in plasma, or to detect the DNA or RNA of tumour-associated viruses is an exciting advance and one that should lead to several new ways of diagnosing cancer and monitoring its therapy over the next decade.

Professor Philip J Johnson

Editor-in-Chief