Shall we settle for low-level evidence?

cancer is only moderately sensitive to radiation therapy and satisfactory tumor control requires fairly high delivered dose. Historically this has been achieved by combination of external-beam radiotherapy (EBRT) with intracavitary brachy-therapy. While dose distribution of EBRT is fairly homogenous, inverse-square law determines most of the dose distribution in brachytherapy. The dilemma has been to deliver as high dose as possible to the target (tumor) sparing adjacent organs at risk. Earlier published data by teams in Vienna and Paris has resulted in the guidelines for conformal brachytherapy. In this issue Narayan et al. [1] describes their long-term experience of delivering conformal brachytherapy with the assistance of much simpler technique, transabdominal ultrasound, than prescribed by other authors. Transabdominal ultrasound is widely available and other centres can easily adapt this method. The reported efficacy of local control and toxicity profile is comparable to previously reported results by other authors. Sample size in this report is fairly large and patients are treated quite homogenously over the years with a few changes in brachytherapy fractionation. Posttreatment magnetic resonance imaging (MRI) elegantly performs quality control of this study. All in all it is exciting that another modality is now available for image guided conformal brachytherapy. The described modality is effective, practical and perhaps cheaper than earlier reported techniques. For all above I would like to congratulate the authors. Though as Bertrand Russell said, " in all affairs it's a healthy thing now and then to hang a question mark on the things you have long taken for granted. " Below are a few thoughts, which I feel are left unanswered: (1) Is this evidence sufficient to change our practice? This is a retrospective analysis of a single institution. In medical oncology such results will only be used as hypothesis generating and will never be accepted as practice changing by physicians or accepted by the regulatory authorities like European Medicines Agency (EMA) and US Food and Drug Administration (FDA). Unfortunately authors does not describe if they plan to validate their results through a randomized prospective trial. I read their conclusions as, " this is it, this is the state of the art. " I strongly recommend authors to continue their work to achieve level-one evidence in this field. (2) Can we further improve local control? Patterns of failure at local site are not addressed. They describe the number of central relapses and that the frequency of these …