Review for 10.1186/s12876-023-02697-4 (2023)

Reviewer’s report
Title: 
Determining the survival benefit of postoperative radiotherapy in patients
with pT1-3N1M0 rectal cancer undergoing total mesorectal excision: a
retrospective analysis
Version: 
0 
Date: 
30 Jul 2022
Reviewer's report:
The authors of the study revealed that for rectal cancer pT1-3N1M0 operated on
without neodjuvant treatment not always postoperative radiotherapy is necessary.
They found that only in tumours larger that 50mm and when there were 3
positive lymph nodes in the specimen postoperative radiotherapy is associated
with survival benefit. The analysed data from SEER database and performed
propensity score matching to eliminate the influence of possible confounders
differently distributed in analysed groups. 
The study is interesting as after introduction of TME the rate of local recurrences
diminished significantly. Still some studies, i.e. Dutch TME trial, emphasised the
value of radiotherapy as neoadjuvant treatment. The statistical analysis is
performed and explained properly.
There are some issues that should be addressed before publication:
1) There are may censored observations in all survival curves, even when only 5
year follow-up is taken into consideration. The authors should specify what was
the actual median follow-up of the analysed patients and how many patients
were lost to follow-up. With so many censored observation the data might be not
reliable when survival is analysed. 
2) Introduction - The abbreviation should be LARC not LAGC
3) The authors stated that high quality of TME is necessary to achieve optimal
oncological results without postoperative radiotherapy. On the other hand, they
wrote in the discussion that the quality of rectal specimen was unknown in the
study. This is inconsistent. Analysed patients were operated on between 2004
and 2016 so the quality of surgery may be different during 12 years. 
4) Results section - the authors stated that all patients had underwent radical
surgery. Please specify whether only R0 patients were included or R1 as well?
5) Discussion - the authors stated that radiotherapy impaired anal function and
voiding but did not mention that this complication may be the results of surgery
and sacral nerves injury not radiotherapy only.
6) Discussion - the abbreviation LPLN should be explained. 
7) Discussion - the word mesentery should be changed into mesorectum in the
sentence "Smooth and intact mesentery"
8) Introduction - the authors cite NCCN guidelines but they did not comment
total neoadjuvant treatment (TNT) that is included in the current NCC guidelines
and more and more commonly adopted clinical practice. At least a couple os
sentences on this issue should be added to discussion with speculation whether
only adjuvant chemotherapy may be better that TNT?
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Is the study design appropriate to answer the research question (including the use
of appropriate controls), and are the conclusions supported by the evidence
presented?
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Yes
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from apparent manipulation?
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