Can neoadjuvant chemoradiotherapy be omitted in cT2N+ and cT3 mid-rectal cancer: Protocol for a prospective, observational, cohort study (CANO)

Feza Karakayali; Cigdem Arslan; Tayfun Bisgin; Ilknur Erenler Bayraktar; Onur Bayraktar; Aras Emre Canda

doi:10.1371/journal.pone.0321819

Peer Review History

Original SubmissionMarch 11, 2025
13 Jun 2025 Decision Letter - Alessandra Castelluccia, Editor Dear Dr. Arslan, One of the reviewers has recommended rejection of the manuscript, while the other has suggested minor revisions. After considering both sets of comments, we believe that the paper has the potential to be reconsidered for publication, provided that the concerns raised by both reviewers are thoroughly addressed. We therefore invite you to revise and resubmit your manuscript, incorporating the suggestions and addressing the issues raised by both reviewers. Please include a detailed response to each comment in your resubmission. Please submit your revised manuscript by Jul 28 2025 11:59PM. If you will need more time than this to complete your revisions, please reply to this message or contact the journal office at plosone@plos.org . When you're ready to submit your revision, log on to https://www.editorialmanager.com/pone/ and select the 'Submissions Needing Revision' folder to locate your manuscript file. 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Please do not edit.] Reviewers' comments: Reviewer's Responses to Questions Comments to the Author 1. Does the manuscript provide a valid rationale for the proposed study, with clearly identified and justified research questions? Reviewer #1: No Reviewer #2: Yes ******** 2. Is the protocol technically sound and planned in a manner that will lead to a meaningful outcome and allow testing the stated hypotheses??> Reviewer #1: No Reviewer #2: Yes ****** 3. Is the methodology feasible and described in sufficient detail to allow the work to be replicable??> Reviewer #1: No Reviewer #2: Yes ****** 4. Have the authors described where all data underlying the findings will be made available when the study is complete??> The PLOS Data policy Reviewer #1: No Reviewer #2: Yes ****** 5. Is the manuscript presented in an intelligible fashion and written in standard English??> Reviewer #1: Yes Reviewer #2: Yes ****** Please use the space provided to explain your answers to the questions above and, if applicable, provide comments about issues authors must address before this protocol can be accepted for publication. You may also include additional comments for the author, including concerns about research or publication ethics. You may also provide optional suggestions and comments to authors that they might find helpful in planning their study. Reviewer #1: Dear authors, The aim of minimising toxicity in rectal cancer treatment by avoiding unnecessary radiotherapy or chemotherapy is a good one. Unfortunately, your non-randomised approach does not seem accurate enough to provide robust data. The non-randomised decisions made by the 'multidisciplinary council' will lead to unadjustable bias. Furthermore, your inclusion criteria did not recognise risc parameters such as EMVI or lateral lymph nodes. You do not perform MSS/MSI testing before treatment what should be mandatory. As surgery seems to be mandatory in your trial, the trend towards organ preservation is not acknowledged in your trial. You did not describe whether restaging will be performed after NCRT. In addition, the follow-up scheme, even if it is considered standard, should be described in your paper. Reviewer #2: Thank you for the opportunity to review the study protocol entitled “CANO trial.” This prospective, multicenter, observational study aims to compare outcomes between upfront total mesorectal excision (TME) and TME following neoadjuvant treatment in patients with cT2N+ or cT3Nany mid-rectal cancer. The protocol is well-structured and addresses a clinically relevant question. While the overall design is commendable, I have a few methodological concerns that should be clarified: Minor Comments: 1. MRI Evaluation Consistency: Given the central role of MRI in risk stratification, the protocol should address how inter-institutional variability in MRI interpretation will be minimized. Consider including provisions such as standardized educational sessions or the use of reference image sets to ensure consistency across sites. 2. Statistical Methods: Further details are warranted regarding the planned multivariable regression analysis. Specifically, please clarify: • The covariates to be included in the model • Whether a Cox proportional hazards model will be used • How the two treatment strategies will be compared—e.g., via propensity score adjustment, matching, or inverse probability weighting 3. Heterogeneity in Neoadjuvant Treatment (nCRT vs TNT): The inclusion of both conventional neoadjuvant chemoradiotherapy (nCRT) and total neoadjuvant therapy (TNT) could introduce heterogeneity in the analysis. As TNT has been associated with improved DFS in some studies, how do the authors plan to account for or stratify the impact of TNT separately from standard nCRT? ****** what does this mean? ). If published, this will include your full peer review and any attached files. If you choose “no”, your identity will remain anonymous but your review may still be made public. Do you want your identity to be public for this peer review? For information about this choice, including consent withdrawal, please see our Privacy Policy Reviewer #1: No Reviewer #2: No ******** [NOTE: If reviewer comments were submitted as an attachment file, they will be attached to this email and accessible via the submission site. Please log into your account, locate the manuscript record, and check for the action link "View Attachments". If this link does not appear, there are no attachment files.] While revising your submission, please upload your figure files to the Preflight Analysis and Conversion Engine (PACE) digital diagnostic tool, https://pacev2.apexcovantage.com/ . PACE helps ensure that figures meet PLOS requirements. To use PACE, you must first register as a user. Registration is free. Then, login and navigate to the UPLOAD tab, where you will find detailed instructions on how to use the tool. If you encounter any issues or have any questions when using PACE, please email PLOS at figures@plos.org . Please note that Supporting Information files do not need this step. https://doi.org/10.1371/journal.pone.0321819.r001
Revision 1
23 Jun 2025 Author Response Responses to the Comments Editor# Dear Editor, We have reviewed the feedback from you and the reviewers. Taking all feedback into account, we have made several major revisions to our study, which are outlined below. 1. We changed the study design from a non-inferiority design to an observational cohort study. Upon concluding that collecting data from nearly 2000 patients within five years would not be feasible, we conducted a new power analysis. These changes have been updated in the manuscript and the clinicaltrials.gov registry. The ethics committee re-evaluated and approved this new design. 2. We removed the term “non-inferiority” from the study title. Accordingly, all related documents have been updated, and new approvals have been obtained from the ethics committee. We are including the latest versions of these documents in our submission. 3. Regarding the reviewers’ comments: EMVI and lateral lymph node status were already part of our dataset and were being recorded. We have now included these as inclusion criteria as well. 4. The reviewers expressed concerns about multidisciplinary tumor boards and radiology. Our study website already includes a frequently asked questions (FAQ) section for participants. This section contains examples of standardized MR and pathology reports. It also states that support will be provided by the steering committee members’ centers for multidisciplinary board consultations and second opinions on MR and pathology, if requested by participating centers. We have now explicitly mentioned this in the manuscript as well. Sincerely, Cigdem Arslan, MD Reviewer #1: Dear reviewer, Thank you for your substantial contributions. We have attempted to revise our protocol accordingly. Please find detailed explanations below. We hope that we have been able to address the limitations of our study. Kind regards Cigdem Arslan, MD 1- The aim of minimizing toxicity in rectal cancer treatment by avoiding unnecessary radiotherapy or chemotherapy is a good one. Unfortunately, your non-randomised approach does not seem accurate enough to provide robust data. The non-randomized decisions made by the 'multidisciplinary council' will lead to unadjustable bias. Response: We fully acknowledge this limitation and have strengthened our statistical analysis plan accordingly. Statistical methods have been revised in the manuscript and highlighted in yellow. To address potential selection bias, we will estimate propensity using logistic regression with relevant covariates and adjust for the propensity score in the primary Cox regression analysis. Additionally, we will conduct sensitivity analyses using both propensity score matching (1:1 nearest neighbor) and inverse probability of treatment weighting (IPTW) to further mitigate bias and ensure the robustness of our results. Although this cannot completely eliminate bias, we believe that these methods can minimize this limitation in an observational study aiming to reflect real-world data. 2- Furthermore, your inclusion criteria did not recognize risk parameters such as EMVI or lateral lymph nodes. Response: We assumed that, in the presence of these factors, the MDT would routinely decide on neoadjuvant therapy. However, you are right, and we have now included these factors in the inclusion and exclusion criteria. 3- You do not perform MSS/MSI testing before treatment what should be mandatory. Response: Unfortunately, MSI testing is not yet performed as a standard in endoscopic pathology in Türkiye. Many centers offer it as an additional test, which is time consuming and usually not covered by insurance and results in extra costs for patients. Therefore, MSI is only tested in endoscopic pathology if the center routinely tests it or if the patient consents to be tested in another institution with extra costs. For this reason, we could not specify unknown pre-treatment MSI status as an exclusion criterion. However, MSI testing is routinely performed in final surgical pathology in our country. Patients found to have MSI (+) in surgical pathology will not be included in the final analysis. Similarly, patients who had preoperative MSI testing (if performed), were found positive, and/or received immunotherapy will also be excluded from the final analysis. We have revised our flow chart and protocol accordingly to reflect this approach. Also, we have discussed these issues in limitations section. 4- As surgery seems to be mandatory in your trial, the trend towards organ preservation is not acknowledged in your trial. 5- You did not describe whether restaging will be performed after NCRT. In addition, the follow-up scheme, even if it is considered standard, should be described in your paper. Response: Our database includes restaging and follow-up data and the dates of the examinations detailly. These issues have been added to the methods section in separate paragraphs in the revised manuscript. Thank you. Reviewer #2: Dear reviewer, Thank you for your valuable comments. We have tried to address all in the revised version Kind regards Cigdem Arslan, MD 1. MRI Evaluation Consistency: Given the central role of MRI in risk stratification, the protocol should address how inter-institutional variability in MRI interpretation will be minimized. Consider including provisions such as standardized educational sessions or the use of reference image sets to ensure consistency across sites. Response: In our study, we aim to observe real-world outcomes. Due to logistical challenges, we are unable to perform centralized radiological and pathological assessments. However, our study website includes a frequently asked questions (FAQ) section where the standards for pathology and MRI reports are clearly described (https://arastirma.tkrcd.org.tr/cano). Furthermore, during the national Zoom meeting held on June 23, 2025, with centers interested in participating, the radiological and pathological standards were shared with all potential participants. It was also emphasized during the meeting—and published on the website—that centers unable to meet these standards would be offered independent radiologic/pathologic evaluation and MDT (support by TSCRS. We are including this statement in our protocol as well. Thank you. 2. Statistical Methods: Further details are warranted regarding the planned multivariable regression analysis. Specifically, please clarify: • The covariates to be included in the model • Whether a Cox proportional hazards model will be used • How the two treatment strategies will be compared—e.g., via propensity score adjustment, matching, or inverse probability weighting Response: Thank you very much for your valuable and constructive comments. We have rewritten the statistical analysis section in the manuscript. Briefly; Age, sex, clinical T and N stage, tumor differentiation, neoadjuvant treatment regimen, interval between RT and surgery, comorbidities, performance status, postoperative complications, tumor histology, pathologic TME quality, and center effect. Cox proportional hazards models will be used for time-to-event outcomes (DFS, OS). Direct TME vs. nCRT+TME will be compared using propensity score adjustment in the primary analysis, with sensitivity analyses using propensity score matching and IPTW. 3. Heterogeneity in Neoadjuvant Treatment (nCRT vs TNT): The inclusion of both conventional neoadjuvant chemoradiotherapy (nCRT) and total neoadjuvant therapy (TNT) could introduce heterogeneity in the analysis. As TNT has been associated with improved DFS in some studies, how do the authors plan to account for or stratify the impact of TNT separately from standard nCRT? Response: In the final analysis, we will also perform subgroup analyses comparing different neoadjuvant treatment regimens with each other. Attachments Attachment Submitted filename: Response to reviewers.docx https://doi.org/10.1371/journal.pone.0321819.r002
21 Oct 2025 Decision Letter - Alessandra Castelluccia, Editor Can neoadjuvant chemoradiotherapy be omitted in cT2N+ and cT3 mid-rectal cancer: Protocol for a prospective observational cohort study (CANO) PONE-D-25-12918R1 Dear Dr. Arslan, We’re pleased to inform you that your manuscript has been judged scientifically suitable for publication and will be formally accepted for publication once it meets all outstanding technical requirements. Within one week, you’ll receive an e-mail detailing the required amendments. When these have been addressed, you’ll receive a formal acceptance letter and your manuscript will be scheduled for publication. An invoice will be generated when your article is formally accepted. Please note, if your institution has a publishing partnership with PLOS and your article meets the relevant criteria, all or part of your publication costs will be covered. Please make sure your user information is up-to-date by logging into Editorial Manager at Editorial Manager® and clicking the ‘Update My Information' link at the top of the page. For questions related to billing, please contact billing support . If your institution or institutions have a press office, please notify them about your upcoming paper to help maximize its impact. If they’ll be preparing press materials, please inform our press team as soon as possible -- no later than 48 hours after receiving the formal acceptance. Your manuscript will remain under strict press embargo until 2 pm Eastern Time on the date of publication. For more information, please contact onepress@plos.org. Kind regards, Alessandra Castelluccia, M.D. Academic Editor PLOS ONE Additional Editor Comments (optional): Reviewers' comments: Reviewer's Responses to Questions Comments to the Author 1. Does the manuscript provide a valid rationale for the proposed study, with clearly identified and justified research questions? Reviewer #2: Yes Reviewer #3: Yes ******** 2. Is the protocol technically sound and planned in a manner that will lead to a meaningful outcome and allow testing the stated hypotheses??> Reviewer #2: Partly Reviewer #3: Yes ****** 3. Is the methodology feasible and described in sufficient detail to allow the work to be replicable??> Reviewer #2: Yes Reviewer #3: Yes ****** 4. Have the authors described where all data underlying the findings will be made available when the study is complete??> The PLOS Data policy Reviewer #2: Yes Reviewer #3: Yes ****** 5. Is the manuscript presented in an intelligible fashion and written in standard English??> Reviewer #2: Yes Reviewer #3: Yes ****** Please use the space provided to explain your answers to the questions above and, if applicable, provide comments about issues authors must address before this protocol can be accepted for publication. You may also include additional comments for the author, including concerns about research or publication ethics. You may also provide optional suggestions and comments to authors that they might find helpful in planning their study. Reviewer #2: Thank you for the comments and replies to my review. The authors responded to all the comments appropriately. Although there are several limitations in this study, it may provide valuable information. Reviewer #3: authors have provided satisfactory responses to reviewers concerns. please consider: -add discussion of possible adjuvant treatments for pathology findings of positive resection margins, positive lymph nodes, EMVI, incomplete TME ****** what does this mean? ). If published, this will include your full peer review and any attached files. If you choose “no”, your identity will remain anonymous but your review may still be made public. Do you want your identity to be public for this peer review? For information about this choice, including consent withdrawal, please see our Privacy Policy Reviewer #2: No Reviewer #3: No ******** https://doi.org/10.1371/journal.pone.0321819.r003
Formally Accepted
Acceptance Letter - Alessandra Castelluccia, Editor PONE-D-25-12918R1 PLOS ONE Dear Dr. Arslan, I'm pleased to inform you that your manuscript has been deemed suitable for publication in PLOS ONE. Congratulations! Your manuscript is now being handed over to our production team. At this stage, our production department will prepare your paper for publication. This includes ensuring the following: * All references, tables, and figures are properly cited * All relevant supporting information is included in the manuscript submission, * There are no issues that prevent the paper from being properly typeset You will receive further instructions from the production team, including instructions on how to review your proof when it is ready. Please keep in mind that we are working through a large volume of accepted articles, so please give us a few days to review your paper and let you know the next and final steps. Lastly, if your institution or institutions have a press office, please let them know about your upcoming paper now to help maximize its impact. If they'll be preparing press materials, please inform our press team within the next 48 hours. Your manuscript will remain under strict press embargo until 2 pm Eastern Time on the date of publication. For more information, please contact onepress@plos.org. You will receive an invoice from PLOS for your publication fee after your manuscript has reached the completed accept phase. If you receive an email requesting payment before acceptance or for any other service, this may be a phishing scheme. Learn how to identify phishing emails and protect your accounts at https://explore.plos.org/phishing. If we can help with anything else, please email us at customercare@plos.org. Thank you for submitting your work to PLOS ONE and supporting open access. Kind regards, PLOS ONE Editorial Office Staff on behalf of MD Alessandra Castelluccia Academic Editor PLOS ONE https://doi.org/10.1371/journal.pone.0321819.r004

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