Reviewer's report
Title:Metachronous metastases- and survival-analysis show prognostic
importance of lymphadenectomy for colon carcinomas
Version: 2Date:14 January 2012
Reviewer: Dieter Hoelzel
Reviewer's report:
This is a well written paper with a well defined question and adequately
described, sound data. The background is a large, prospective, well documented,
patient cohort from a university hospital. A specific feature is the consequent
selection with clearly defined criteria, which results in a homogenous cohort.
Nonetheless, the conclusion is only partially comprehensible. The lymph node
involvement – that is the number of positive lymph nodes – is the most important,
classical, prognostic factor. This is shown by the multivariate Cox regression. But
a correlation is not causation or “post hoc ergo propter hoc” would be a logical
fallacy. Therefore, the prognostic relevance of positive lymph nodes is not a
justification for the lymphadenectomy. If positive lymph nodes are not the cause
of distant metastases then the reliable identification of a positive lymph node
status would be sufficient for the indication of an adjuvant treatment comparable
to the sentinel lymph node procedure in other cancers. Therefore, the last
sentence in the conclusion and the last chapter of the discussion should be
specified, perhaps with an additional paper e.g. Yachida Nature 2010 and PA04.
In addition, the following improvements are recommended:
The term stage is a defined term. Therefore, the term N-stage, T-stage should be
replaced by N-category and T-category, also in the figures.
Table 1: A line with the number of deaths in both groups should be added. The
differences in the Cox models are in part dependent on the different numbers of
each event, metastases or cancer related death or all dependent and in Table 3
all deaths, also the cancer independent cases.
Fig.1: The reduction of the cohort is reasonable but the numbers of the excluded
patients are not reproducible. The groups are not disjunctive. Therefore, the sum
must be greater then the number of the excluded 645 or 329 patients.
It would be very informative for interested readers, if the selection process would
be described with tables with the T-category pT1, pT2, pT3, pT4 and others listed
as columns and as lines R1/R2, previous second non-CRC, synchronous
metastases, with further grouped criteria such as age <50y, or positive family
history . These tables should replace the two boxes.
The exclusion criteria primary surgery is actual unnecessary because
Kaplan-Meier curves and Cox models can use cases with shorter follow-up. But a
new evaluation would not change the conclusion and is therefore not necessary.
Fig.2 d should describe the grade dependent survival instead of N-category N0
or N2
Level of interest: An article of importance in its field
Quality of written English: Acceptable
Statistical review: Yes, and I have assessed the statistics in my report.
Reviewer's report
Title:Metachronous metastases- and survival-analysis show prognostic
importance of lymphadenectomy for colon carcinomas
Version: 2Date:14 January 2012
Reviewer: Dieter Hoelzel
Reviewer's report:
This is a well written paper with a well defined question and adequately
described, sound data. The background is a large, prospective, well documented,
patient cohort from a university hospital. A specific feature is the consequent
selection with clearly defined criteria, which results in a homogenous cohort.
Nonetheless, the conclusion is only partially comprehensible. The lymph node
involvement – that is the number of positive lymph nodes – is the most important,
classical, prognostic factor. This is shown by the multivariate Cox regression. But
a correlation is not causation or “post hoc ergo propter hoc” would be a logical
fallacy. Therefore, the prognostic relevance of positive lymph nodes is not a
justification for the lymphadenectomy. If positive lymph nodes are not the cause
of distant metastases then the reliable identification of a positive lymph node
status would be sufficient for the indication of an adjuvant treatment comparable
to the sentinel lymph node procedure in other cancers. Therefore, the last
sentence in the conclusion and the last chapter of the discussion should be
specified, perhaps with an additional paper e.g. Yachida Nature 2010 and PA04.
In addition, the following improvements are recommended:
The term stage is a defined term. Therefore, the term N-stage, T-stage should be
replaced by N-category and T-category, also in the figures.
Table 1: A line with the number of deaths in both groups should be added. The
differences in the Cox models are in part dependent on the different numbers of
each event, metastases or cancer related death or all dependent and in Table 3
all deaths, also the cancer independent cases.
Fig.1: The reduction of the cohort is reasonable but the numbers of the excluded
patients are not reproducible. The groups are not disjunctive. Therefore, the sum
must be greater then the number of the excluded 645 or 329 patients.
It would be very informative for interested readers, if the selection process would
be described with tables with the T-category pT1, pT2, pT3, pT4 and others listed
as columns and as lines R1/R2, previous second non-CRC, synchronous
metastases, with further grouped criteria such as age <50y, or positive family
history . These tables should replace the two boxes.
The exclusion criteria primary surgery is actual unnecessary because
Kaplan-Meier curves and Cox models can use cases with shorter follow-up. But a
new evaluation would not change the conclusion and is therefore not necessary.
Fig.2 d should describe the grade dependent survival instead of N-category N0
or N2
Level of interest: An article of importance in its field
Quality of written English: Acceptable
Statistical review: Yes, and I have assessed the statistics in my report.
Please review this paper.
user
Reviewer's report
Title:Metachronous metastases- and survival-analysis show prognostic
importance of lymphadenectomy for colon carcinomas
Version: 2Date:14 January 2012
Reviewer: Dieter Hoelzel
Reviewer's report:
This is a well written paper with a well defined question and adequately
described, sound data. The background is a large, prospective, well documented,
patient cohort from a university hospital. A specific feature is the consequent
selection with clearly defined criteria, which results in a homogenous cohort.
Nonetheless, the conclusion is only partially comprehensible. The lymph node
involvement – that is the number of positive lymph nodes – is the most important,
classical, prognostic factor. This is shown by the multivariate Cox regression. But
a correlation is not causation or “post hoc ergo propter hoc” would be a logical
fallacy. Therefore, the prognostic relevance of positive lymph nodes is not a
justification for the lymphadenectomy. If positive lymph nodes are not the cause
of distant metastases then the reliable identification of a positive lymph node
status would be sufficient for the indication of an adjuvant treatment comparable
to the sentinel lymph node procedure in other cancers. Therefore, the last
sentence in the conclusion and the last chapter of the discussion should be
specified, perhaps with an additional paper e.g. Yachida Nature 2010 and PA04.
In addition, the following improvements are recommended:
The term stage is a defined term. Therefore, the term N-stage, T-stage should be
replaced by N-category and T-category, also in the figures.
Table 1: A line with the number of deaths in both groups should be added. The
differences in the Cox models are in part dependent on the different numbers of
each event, metastases or cancer related death or all dependent and in Table 3
all deaths, also the cancer independent cases.
Fig.1: The reduction of the cohort is reasonable but the numbers of the excluded
patients are not reproducible. The groups are not disjunctive. Therefore, the sum
must be greater then the number of the excluded 645 or 329 patients.
It would be very informative for interested readers, if the selection process would
be described with tables with the T-category pT1, pT2, pT3, pT4 and others listed
as columns and as lines R1/R2, previous second non-CRC, synchronous
metastases, with further grouped criteria such as age <50y, or positive family
history . These tables should replace the two boxes.
The exclusion criteria primary surgery is actual unnecessary because
Kaplan-Meier curves and Cox models can use cases with shorter follow-up. But a
new evaluation would not change the conclusion and is therefore not necessary.
Fig.2 d should describe the grade dependent survival instead of N-category N0
or N2
Level of interest: An article of importance in its field
Quality of written English: Acceptable
Statistical review: Yes, and I have assessed the statistics in my report.
assistant