Review for 10.1186/s12876-020-01464-z (2020)

Reviewer’ s report
Title: Establishment of prognostic nomogram for elderly colorectal cancer patients: a SEER
database analysis
Version: 0Date: 28 Jul 2020
Reviewer's report:
This is a well written article about models of overall survival and cancer-specific survival in
elderly colorectal cancer patients. However I have some comments:- Although the authors mentioned that this is a novel study about association of age and risks forprognosis of elderly colorectal cancer patients, there is an article that compared the survival andprognostic factors among different age groups (Kocián P, et al. Is colorectal cancer a moreaggressive disease in young patients? A population-based study from the Czech Republic. CancerEpidemiol, 2019)- Marital status is the only 'non-biological' variable in this study. Why has marital status beenchosen instead of race/ethnicity, nursing home resident, or smoking status for example?- For marital status, there are more option than 'married' and 'unmarried' (single, widow, divorce,separated)- The exclusion of patients who did not undergo surgery might lead to a bias. Older patients and/orin worse clinical conditions probably were not fit for surgery and display a higher mortality riskfor colorectal cancer
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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?
YesAre the methods sufficiently described to allow the study to be repeated?YesIs the use of statistics and treatment of uncertainties appropriate?
Yes
Is the presentation of the work clear?
YesAre the images in this manuscript (including electrophoretic gels and blots) free from apparent
manipulation?
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