Review for 10.1186/s12876-022-02270-5 (2022)

Title: Homogeneous and heterogeneous risk and prognostic factors for lung metastasis in
colorectal cancer patients
Version: 0 Date: 25 Jan 2022
Reviewer's report:
Wang and colleagues analyzed the SEER data for risk and prognostic factors for lung metastasis
in CRC patients. Overall, the results are interesting but very much expected. However, a number
of limitations were identified in the methods, as outlined below.
ABSTRACT
The title and some of the associated texts are somewhat confusing. It is not clear whether the
outcome is CRC or lung metastasis. The second line in the abstract clarified it. A suggestion
for the title “Homogeneous and heterogeneous risk and prognostic factors for lung metastasis
in colorectal cancer patients.” “Risk and prognostic factors of lung metastasis” instead of
“occurrence and prognostic factors” should be used throughout the manuscript.
METHODS
1. Given that stage I and low-risk stage II CRC patients have much lower risk of metastasis, I see
no reason for including these patients in the analysis. This may bias your findings. Alternatively,
subgroup analysis according to stage should be performed (e.g., stage 1, II, III, and IV) and the
results should be reported as the main findings.
2. Did the authors have information on important comorbidities such as diabetes, renal disease,
heart failure, and myocardial infarction? These are important prognostic and treatment-related
factors of CRC and should be addressed in the manuscript.
3. “According to the results of multivariable logistic regression and multivariable Cox regression
analysis, the intersection of the occurrence factors and prognostic factors was used to identify
homogeneous or heterogeneous factors.” It is not clear what the authors meant by this.
4. The end-point for prognosis of lung metastasis was not defined in the manuscript. In Table
2, the authors indicated that they investigated all-cause mortality (overall survival). If so, this
should be explicitly defined in the manuscript as well as the follow-up time.
RESULTS
1. “Multivariable Cox regression confirmed that older age, unmarried status, uninsured status,
right colon, poor histological differentiation, more lymphatic metastases, positive CEA, liver
metastasis, bone metastasis, brain metastasis and no surgical treatment of the primary site were
all risk factors”. It is not clear….risk factors for which outcome? Poorer prognosis?
2. 10,598 (5.22%) patients developed lung metastasis so why were 8,867 patients included in
the analysis for prognostic factors for lung metastasis? This was not clarified in the manuscript.
3. Table 1: The Chi-square statistics and the corresponding p-values should be deleted.
4. Tables 1 & 2: The variables/factors that were adjusted for in the multivariable analyses should
be listed as footnotes.
MINOR
1. Convert all percentages and follow-up or survival times to one decimal place.
2. Abstract: …………….bone metastasis and brain metastasis were risk and prognostic factors
of lung metastasis.
3. This sentence needs scientific editing: “However, patients with black race and left colon,
rectum, and stage T4 disease were more likely to develop lung metastasis, while patients with
right colon cancer and no surgical treatment of the primary site were associated with poor
survival.”
4. Abstract: CRC patients with lung metastasis exhibit homogeneous and heterogeneous risk
and prognostic factors.
Overall, the manuscript needs scientific editing.