The link between the XMRV retrovirus and patients with chronic fatigue syndrome is probably the result of laboratory contamination, according to two new studies published today by the journal Science.

In 2009, a report that patients with chronic fatigue syndrome were infected with XMRV attracted considerable interest, but subsequent studies published in other journals by independent scientists failed to detect XMRV in other groups of patients with the condition. (Vincent Lombardi et al, Science Express 8 October 2009; Science 23 October 2009)

A microchip can capture and take snapshots of rare cancer cells circulating in the blood, which may provide a way to monitor patients after tumor removal and could eventually guide treatment, reports a new study in Science Translational Medicine. These circulating tumor cells, though small in number, might be an important marker that can help doctors quickly spot any changes in cancer progression and determine whether or not a particular treatment is working.