[Isolated tumour cells: 'seek, and ye shall find']

In a study recently published in this journal, Van der Zaag et al. found that the distinction made by pathologists between micrometastases and isolated tumour cells in lymph nodes of patients with colon cancer was not uniform. Such a classification only has clinical relevance to cancer patients if pathologists use generally accepted definitions. At the same time it is of great importance to be aware that the more one looks, the more often one will find tumour cells outside the primary tumour--finally perhaps in everyone who has cancer. Whether these tumour cells are clinically relevant is not always sure.