Sentinel Lymph Node Mapping in Lung Cancer: A Pilot Study for the Detection of Micrometastases in Stage I Non-Small Cell Lung Cancer

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

#1. “using OSNA (one-step nucleic acid amplification)” analysis >> please provide reference[s] 

#2. LNs were de-171 fined as `negative' or `positive' according to established cut-off values 39,56,57. Therefore, negative nodes are classified for CK 19 mRNA ccP/μl as less than 250.>> The reviewer guessed 39,56,57 referred to ref-39, ref-56, ref-57 respectively, so please clarify and double check because there were no ref-56 or ref-57 in the current manuscript. .

 #3 “OSNA has been successfully applied in lung cancer, because of its diagnostic sensitivity” >> suggest to comment on recent relevant studies such as Sci Rep. 2022 May 4;12(1):7297 & PLoS One. 2022 Mar 21;17(3):e0265603.

Author Response

Thank you for your valuable suggestions

#1 we have provided references as you recommended

#2 we have corrected the typos

#3 Comments on these relevant studies were added, according to your suggestion

Reviewer 2 Report

Comments and Suggestions for Authors

1. You claim that it is effective and safe to perform sentinel lymph node detection using the OSNA method in patients with early-stage lung cancer. However, many studies have already reported that sentinel lymph node detection using the OSNA technique is effective.

I can't find any new information in your paper that haven't been published in previous research. What differentiates your research from existing studies?

Authors should describe in detail what makes this study unique compared to previously published studies in the Introduction and Discussion sections.

 

2. Authors should add a few pictures showing the extent of radiopharmaceutical distribution or sentinel lymph node uptake after radiopharmaceutical agent injection.

 

3. In the Discussion section, a detailed explanation and rationale for the results obtained in this study should be provided. The Discussion section of this paper focuses on explaining the results of previously published studies. 

Author Response

Der Reviewer,

I would like to thank you for your comments

1. As you reported, previous studies have demonstrated the diagnostic value of OSNA for the assessment of lymph node metastases. Due to its characteristics, OSNA has been shown to be effective in the intraoperative diagnosis of lymph node metastases in non-small cell lung cancer. Although there are studies on the performance of sentinel node detection using OSNA in breast cancer, no previous studies have evaluated the combination of these techniques in lung cancer.

Our study aims to investigate sentinel node detection using a specific radiopharmaceutical for lymphoscintigraphy and to increase the sensitivity of the procedure using OSNA, which is also able to detect lymph node micrometastases.

This information was inserted in the text (from line 85 to 94; from line 262 to 268)

2. The pictures of SPECT/CT are inserted as you suggested (fig 5-6)
3. We modified the discussion according to your suggestions

Reviewer 3 Report

Comments and Suggestions for Authors

The authors report on their findings in a limited cohort of 8 early stage/N0 NSCLC patients in whom a sentinel node mapping was performed using two CT guided injections of 99mTc-tilmanocept for SPECT imaging, intra-operative probe detection and ex vivo, as well as with OSNA evaluation. Given the limited number of subjects, I would be hesitant to make strong recommendations. Having said this,  both procedures for sentinel node mapping (radionuclide/SPECT and OSNA) are not common practice and the experiences of this group in setting up these procedures are valuable to share amongst pulmonologist. The main comment I have is that the authors should provide a comprehensive overview (e.g. table) with the data per patient, as it concerns 8 patients. This would allow the reader to hypothesize and interpret the data independently. Throughout the comments below, the requested additional data will be evident, and the authors may also consider to split it into separate tables, for example on clinic-pathological data/OSNA and SPECT procedure/imaging data. 

 

Introduction

1.     Line 55, mainstay is not the correct academic term that should be used here.

2.     Line 75, it could be wise to list the postoperative complications that were fount by Ma et al. to highlight the importance of a SLNB

 

Methods

3.     Line 119, what was the total injected volume? What was the mean depot volume? What was the mean radioactivity injected?

4.     Line 120-121, what is meant with the context and more peripheral portion of the lesion? We believe other, more universally used, terms should be used here to determine which part of the lesion is meant. Please a clear description of the CT injection procedure and the targeted areas for injection. 

5.     Line 128-130, how is the distribution of the radiopharmaceutical checked? We believe a small volume will not necessarily be visible on CT-imaging. Notion of the injected volumes is important here to determine this.

6.     Line 138-140, what was the (mean) time between CT-guided injection and SPECT-scanning? What SPECT-scan protocol was used (i.e. number of views, detection time per view, window and other reconstruction settings etc.)?

7.     Line 149, we don’t believe in-vivo should be between quotation marks.

8.     Line 155-158, it is unclear how the background signal is determined. It is also unclear how the SLN was determined. 10% of 10 cps is only 11 cps and since radioactivity does not signify constant decay, a value of 10-20% above or below the average background signal does not signify radioactivity in a lymph node. Most other articles use > 3 times the background signal. Why was that not used here?

9.     Line 165, how was the lymph node assessed by a pathologist? For a pathologist to assess a lymph node, it should be embedded in paraffin and sliced up to determine if there were metastatic cells present. Additionally, how was the fatty tissue removed from the lymph nodes without damaging the lymph nodes? 

10.  Line 172-173, this sentence does not follow logic. Do you mean nodes are classified as negative when the CK19 mRNA level was < 250 ccP/uL?

11.  Line 175, How is it possible to have 250±5000 ccP/uL? Can you have a negative ccP/uL value?

 

Results

12.  Line 187, since the abbreviation SLN is introduced earlier in the manuscript, it should be used in this table as well. Additionally, it is not clear whether the amount of lymph nodes (10 SLNs) or the lymph node station (#10) is meant in the table, please specify.

13.  Line 190-120, where all removed lymph nodes assessed with OSNA assay? If so, why perform the SLN procedure?

14.  Line 192, none should be no.

15.  Line 196, the spacing is off in the sentence.

16.  Line 198, neoplastic lymph node involvement is a pleonasm, remove neoplastic as it is not a term often used to describe this.

17.  Line 203-204, it is not clear from the table how these numbers come about. Patient 1 and 2 both have 4 positive lymph node stations and there are 4 levels involved, but only 80% of the positive lymph node stations are involved?

18.  Why was it not possible to perform a SPECT-scan in 2/8 patients? Can the authors add examples of SPECT images (MIP, axial slides, fused and SPECT only)?

19.  Since this data is collected almost 3 years ago, it would add value to this research to add the follow-up and possible (2-year) recurrence rates of these patients.

 

Discussion

20.  Please add a more elaborate overview of other/alternative sentinel node procedures, emphasizing on their pros and cons, and the how this relates to this method. 

21.  Line 210-213, what are those reasons? Additionally, you do not use sentinel lymph nodes, you use or perform an SLN procedure. Lastly, what are the problems that lead to lack of pathological staging of lymph nodes and how can an SLN procedure be used to overcome those in centers where no lymphadenectomy is performed?

22.  Line 216-217, standard of care should not be between quotation marks, because this is true.

23.  Line 227, it is not clear what is meant by vital dye-based techniques. What is vital about it?

24.  Line 245, this line should follow the sentence in line 242.

25.  Line 264-268, we believe this information should be moved to  the introduction or methods.

26.  Line 272, when you would also like to determine if a patient has “skip metastases” would it not be advantages when a tracer also accumulates in the higher echelon nodes and more than 1 SLN can be appointed? 

27.  Line 295-303, we believe this information should be moved to the introduction or methods.

28.  Line 307, this line should say that an SLN procedure in combination with the OSNA assay may open new scenarios.

29.  Line 310-311, mandatory for what?

30.  Please comment on the relatively high number of upstaging events in this cohort, how can this be explained? 

Comments on the Quality of English Language

Please consider editing by an experts, suggestions are given in the review report. 

Author Response

Dear Reviewer,

We would thank you for your appreciated suggestions.

We have adopted all the changes suggested, which have significantly improved the quality of the article.

 

Author Response File: Author Response.pdf

Reviewer 4 Report

Comments and Suggestions for Authors

This study explores the value of sentinel node (SLN) in staging of operable lung cancer. The staging of lung cancer remain an area of debate so topic is very relevant.

The SLN was identified by tumor injection of radiomarker in patients with clinical stage NO.

Analysis of removed SLN was done for CK19 analysis to determine presence of tumor cells using a predefined cutoff for CK11 content.

The paper is very well written and gives a very hands-on description of procedures. The limitation obviously is the low number of patient enrolled in study.

It may help the understanding of the procedure to explain that lymph node sampling was done as usual and thus not directed by the imaging for lymph nodes.

The authors should discuss the potential problem with tumors being CK19 negative as the SLN test relies on the presence of this marker. Allthough 80-90% of lung cancers are CK19 pos, it would add the credibility of the stud if CK19 analysis of the tumors were presented.

Author Response

Dear Reviewer,

We would like to thank you for the revision and the good points you have brought to our attention

We have modified the text according to your suggestions

 

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

The authors had addressed my previous comments

Reviewer 2 Report

Comments and Suggestions for Authors

As I pointed out, the authors revised the paper well. 

Although the small sample size is a weakness of this paper, it is a helpful paper to readers.

Thank you for your hard work revising the paper.