Reacción a "Clinical trial examines efficacy of prostate cancer screening with MRI to reduce overdiagnosis"

This well-designed and well-executed study examines the potential of magnetic resonance imaging (MRI) as a means of reducing overdiagnosis in the early diagnosis of prostate cancer (PC), but without losing sight of the risk of missing potentially lethal tumours. Briefly, the standard approach (biopsy of suspicious lesions associated with random biopsy of the rest of the prostate) is analysed versus biopsy of suspicious lesions alone. The study unfolds in a setting with connotations that make it ideal for any type of screening: an extremely exhaustive follow-up, a target population (Nordic) very disciplined in their health habits and a cancer registry endowed with extraordinary credibility. Only the ‘modest’ participation rate of 50% is surprising compared to similar Scandinavian experiences. To illustrate the point, it is worth noting that the PC screening programme once activated by the University Hospital of Getafe only achieved a participation rate of 20%.

This study addresses an issue central to all initiatives related to the early detection (or screening, which is essentially the same thing) of PC: overdiagnosis, i.e. the detection of potentially non-lethal tumours. It is this circumstance that makes the generalisation of PC screening unfeasible. And only by avoiding the detection of this type of tumour will the benefits of screening - which exist, let us not forget - outweigh its adverse effects. In that sense, MRI has the capacity to act as a filter to avoid the diagnosis of indolent tumours, provided that a very rigorous diagnostic sequence is observed: among other things, in the present study all images (more than 13,000 studies) were interpreted by a team of four radiology specialists with more than five years of MRI experience. In addition, the studies were performed using a state-of-the-art three-tesla resonator. This combination of dedicated radiologist, in Anglo-Saxon terminology, and high-performance equipment is essential to obtain comparable data.

After an average (median, actually) follow-up of about four years, the diagnosis of indolent tumours - i.e. overdiagnosis - decreased by more than 50% compared to the standard approach, with no significant increase in incurable tumours detected to date. This is precisely one of the aspirations of the European Union (EU) Cancer Plan. Currently, several countries, including Spain, are analysing the feasibility of screening programmes for PC that include MRI in the EU. The variety of approaches in each of the pilot centres is truly striking. And yet, it has not yet been incontrovertibly proven that PC screening programmes save lives. Is the effort legitimate, and are European health systems prepared to take on such a burden?