Review for 10.1186/s12876-024-03213-y (2024)

Title: Impact of severe postoperative complications on the prognosis of older patients with
colorectal cancer: A two#center retrospective study
Version: 4 Date: 10 Jan 2024
Reviewer's report:
The authors report on the impact of severe postoperative complications on the prognosis of older
patients with colorectal cancer.
In 2021, the life expectancy at birth in the EU was 80.1 years, however the life expectancy for
80 year-olds rose from 8.4 years in 2005 to 9.2 years in 2015. The growing proportion of elderly
people in the EU (from 4.1% in 2006 to 5.4% in 2016) means that, in 2016, one in every 20
persons living in the EU was aged 80 and over (source: EUROSTAT). In this light, the choice
of topic is important and relevant not only in Asia but also in Europe. The study is well designed
and reported. The main limitations (retrospective nature, only two center data) are acknowledged
by the authors. Although a preliminary review of the article has already been done and it has
been revised on this basis, I would like to ask a number of clarifying questions that also affect
the results. If these are answered, the article is recommended for publication.
Minor issues:
1. The data lacked the average age of the patient groups included in the study. It would be worth
knowing the difference in mean age between the two groups.
2. It is contradictory for me that grade 3 or higher complications according to the Clavien-Dindo
classification were included, but grade 5 mortality was excluded.
3. Three patients who died during their hospital stay were excluded from the study. What was
their age?
4. For rectal tumours, did neoadjuvant treatment, postoperative adjuvant treatment play any
prognostic role in terms of complications?
5. During the study period, surgical techniques have changed, and the number of robotic
surgeries has presumably increased. How can such changes, which are aimed to avoiding
postoperative complications or achieving a complete resection rate, etc., be taken into account
in statistical analysis or, if not, how accurate can the results be considered? Perhaps surgery to
technically homogenise the groups (e.g. separate assessment of robotic surgery cases)?
6. Has subgroup analysis of the rectum or colon occurred? If so, is there any difference?
7. In determining CSS, the way in which the cause of death is classified as cancer or other disease
is crucial. How was it possible to objectively and statistically unbiasedly determine the cause
of death in the two groups of patients in this study, when the older patients had a higher rate of
surgical complications and possibly deaths from these complications?
8. What was the reason for the higher rate of lack of adjuvant treatment in older patients, while
both pStage and lymphatic invasion rates were higher?
9. As described in lines 141-143, avoiding complications would therefore improve CSS and OS
in the older group of patients, whereas postoperative complications in the younger group would
not affect these values. In other words, is it not age but postoperative complications that worsen
survival in older patients? Does the working group have data on the survival of older patients who
did not undergo surgery, depending on the stage of the disease or on the oncological treatment?