Review for 10.1186/s12876-022-02543-z (2022)

Title: Epidemiology and prognostic analysis of patients with pancreatic  signet ring cell
carcinoma: a population-based study
Version: 1 Date: 15 Aug 2022
Reviewer's report:
Dear Author,
I read with interest the manuscript you submitted to BMC Gastroenterology. Please allow me
to make some comments.
Major comments:
1. Importantly, many occasions for scientific English improvement are present throughout the
manuscript, and writing style is often poor. Sentences are often truncated. Moreover, personal
pronouns (ie. we/us) as well as colloquial wording (eg. ‘to our surprise’ in the Results sections)
should be avoided. I strongly suggest an extensive proofreading before submission to an
international scientific journal.
2. In the Introduction: ‘Importantly, the role of chemotherapy and marital status has not been
elucidated.’ Why should marital status be a characteristics of incidence per se? Is it even
comparable to chemotherapy?
3. In the Methods: PSRCC patients diagnosed by ‘microscopic confirmation’ were analyzed.
What does that mean? Which selection criteria were formally utilized?
4. In the Results/Table 1: what does tumor grade refer to? Do the authors mean ‘disease stage’
or differentiation grade (as reported in Line 161-162)? In the latter case, how could they have
tumor differentiation grade for 280 patients if only 100 underwent pancreatectomy?
5. In the Results: “median tumor size of the patients was 4cm, and patients with tumors larger
than 4cm accounted for 28.5%” …. “Patients with tumors size #4 accounted for 28.5%, and
tumors size >4 accounted for 36.9%” . This is an obvious inconsistency. Please, verify. Also,
consider the definition of median: how could it be that, after declaring a median 4cm tumor size,
only 28.5 / 37% of patients had tumors larger than 4cm?
6. Table 2. Please, check for congruity of frequencies and percentages.
7. In the Results: Missing data represent a major limitation of the study (i.e. 81% for nodal status,
35% for tumor size, etc). How did the authors handle this?
Minor comments:
1. In the Introduction: ‘Patients with PSRCC have insidious symptoms and are usually diagnosed
at an advanced stage. Therefore, patients diagnosed with PSRCC usually have a poor prognosis.
Another reason for poor prognosis is easy invasion of surrounding tissues and metastasis.’ These
features belong to pancreatic cancer in general, not only to the signet ring cell phenotype. Please,
rephrase.
2. In the Methods: definition of survival endpoints needs more clarity. I would recommend to
ask for a consultation of a certified biostatistician if necessary.
3. In the Results: “The annual adjusted incidence rate declined over time, from 0.48 per million
in 2000 to 0.16 per million in 2018. …As shown in Fig. 1, the incidences of PSRCC ranged
from 0.480 to 0.160 per million person-years from 2000 to 2018”. P
4. In the Results: “Patients who receive primary surgery had substantially improved OS” How
did the authors determine that such patients underwent primary (namely, upfront) surgery?
5. In the Discussion: “To our knowledge, this study is the most comprehensive study to report
the epidemiology and survival of PSRCC.” Despite the noteworthy sample size, the authors
should consider the multiple and relevant limitations of the data analyzed in the present study.
Please, rephrase.