The two Achilles heels of surgical randomized controlled trials: differences in surgical skills and reporting of average performance.

Randomized controlled trials of surgery are fundamentally different from randomized controlled trials of medications because it is difficult to blind or mask a surgical procedure or perform "sham" operations. An additional challenge is the variation in skills and surgical proficiency of participating centers and surgeons. Addressing heterogeneity in surgical proficiency remains of paramount importance, especially when randomized controlled trials involve a new or complex procedure such as minimally invasive radical surgery.