Some facts are correct, but clarity can help here. First, the actual study used samples collected from multiple clinics and sites across the province of Ontario and in some cases China for validation - not one cohort or clinical assessment site. A statement says otherwise in the review.

Second, while the number of cases may seem small, given that a mass prospective trial that just published assessing liquid biopsies against primary and secondary diagnoses achieved the same sample sizes, this study is still relatively well powered and speaks to the value of retrospective samples in this space. While prospective studies may seem ideal, arguably they are not always best suited.