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Comment on: Risk factors for conversion in laparoscopic and robotic rectal cancer surgery

Editor We appreciate the work by Crippa et al.1 finding that robotic surgery for rectal cancer was associated with a lower risk of conversion. We agree with the authors that conversions should be categorized as reactive conversion and pre-emptive conversion. The definition is in accordance with the consensus of a Delphi study2, differentiating strategic and reactive conversion. The clinical significance of such distinction is that reactive conversion was shown to be associated with increased postoperative morbidity compared with pre-emptive/strategic conversion3. It is suggested that surgeons should have a low threshold for performing pre-emptive/strategic conversion rather than awaiting the need for a reactive conversion3. The authors did not further evaluate the rates of pre-emptive and reactive conversion. By extracting data from their study, we found that the reactive conversion rate was low and comparable between robotic and laparoscopic surgery (5 of 317 (1⋅6 per cent) versus 3 of 283 (1⋅1 per cent); P = 0⋅581) while the pre-emptive conversion rate was much higher for laparoscopic surgery compared with that for robotic surgery (36 of 283 (12⋅7 per cent) versus 11 of 317 (3⋅5 per cent); P < 0⋅05). In our opinion, this finding may indicate that patient selection is more critical in laparoscopic surgery. A more discreet patient selection may help reduce the rate of pre-emptive conversion in laparoscopic surgery. On the other hand, robotic surgery is not that ‘picky’ and it was found that the greatest benefit for robotic surgery was in high-risk patients with obese BMI, male gender and a history of previous abdominal surgery4, which were major causes of pre-emptive conversion in laparoscopic surgery. T. H. Yang and Y. Shen Department of Gastrointestinal Surgery, West China Hospital, Sichuan University, Sichuan, China