Complications and Risk Factors in En Bloc Resection of Spinal Tumors: A Retrospective Analysis on 298 Patients Treated in a Single Institution

Round 1

Reviewer 1 Report

The authors discussed the rarity of primary bone tumors of the spine. En bloc resection used for many of these as well as metastases such as RCC. They discussed the WBB classification. Purpose of en bloc is for tumor control but it comes with difficulty given surrounding noble structures. As such, they designed a retrospective study of previously completed en bloc spinal tumor removal. Preop factors indicating en bloc surgery were colleted as well as post operative surgical complications and adverse events. 

327 en bloc resections performed.  99 patients had at least one major complication and 58 had at least one minor complication. Approximately half of all patients had some sort of complication. 60 patients had intraoperative complications, 65 had  early  postoperative  complications and 64 had late post operative complications. Most complications were severity grade 3 meaning they required complex treatment. 

Median follow up time was 69 months. 5-year OS was 75%, 10-year OS was 67%, affected by relapse not adverse events at the time of surgery. Risk factors for complications were age, type of surgery, previous treatments and previous surgery. 

The authors discuss their findings and relevant literature. Their case numbers are quite high and undoubtedly impressive. They also analyzed the trends from pre and post 2015 and found a higher rate of adverse events after this year. I agree with the authors that it is likely that we as surgeons are more aggressive now that new adjuvant therapies are being developed. The authors should discuss outcome differences from pre- and post- 2015 to truly make this point relevant. 

Highest intraoperative complications are dural tears, visceral injuries and vascular injuries. Early post operative complications were hematoma, CSF leak and pulmonary embolism. Late post operative complications were mainly construct failures followed by infections and wound dehisences. 

Age, previous treatments, previous surgery, and combined ant/post approach was associated with increased complications. Probably most importantly, relapse of disease affects the OS while complications had no effect on OS. I think that this is an extremely important point and should be emphasized.

Ultimately this is a very large study with interesting results that I believe would be valuable addition to the literature. 

Page 4 line 131 lists a percentage 177.59%

Page 12 line 308: “visceral e vascular injuries” should be “visceral and vascular”. 

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Reviewer 2 Report

The authors suggest the importance of completely removing vertebral tumors. The study is interesting, however, I have some concerns to be discussed.

-How do you think about adjuvant therapy?

-What is the novelty of the current study? Please enhance that.

-How do you fill it up after resection？ Did you use bone cement?

-Has the spinal pain improved postoperatively?

-Did you use the non-operative treatment such as caudal injection? Please discuss that point refferring the following manuscript.

Comprehensive treatment outcomes of giant cell tumor of the spine: A retrospective study. Medicine, 101(32), e29963. https://doi.org/10.1097/MD.0000000000029963

-How about the spinla alignment after resection?

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Reviewer 3 Report

Authors reported their surgical experience in en bloc resection of 327 spinal tumors. Paper is well written. Just some points:

- Lines 61-62: Please report better what is the aim of this paper. Surgical outcome? Recurrent? Clinical follow-up?

- Linew 136-138: "We observed that 83 patients (27.8%) received a previous treatment including radiotherapy and/or chemotherapy at the main lesion site before en bloc resection..." Does this affect overall survival?

- Dura tear and visceral injury was reported 34.3% and 17.9%, respectively. This is normal for en bloc resection. Discuss more about intraoperative complications in the discussion section.

- Lines 372-274: "the analysis suggests that double surgical approach (compared to the single one) is related to a doubled risk of complications" This point should be highlighted more in the paper. Please report other previous paper discuss about this.

Overall a good paper.

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Round 2

Reviewer 2 Report

The authors repiled well, so the manuscript is suitable for publication.