Review for 10.1186/1471-230X-13-134 (2013)

Reviewer's report
Title:Improvement of long-term outcomes in pancreatic cancer within the
gemcitabine era: A collaborative retrospective multicenter clinical review of 1,082
patients
Version: 1Date:14 May 2013
Reviewer: david goldstein
Reviewer's report:
This report examines outcomes for Pancreatic Cancer over a 10 year period in
nine Japanese centres. The aim of the study is to assess the impact of changing
patterns in use of Gemcitabine the change in outcome and the possible impact of
an increased use of gemcitabine to explain the improvements seen.
They examined records of 1082 patients and divided the decade into two five
year periods which were distinguished by an increased gemcitabine use in the
second five year period of 51% vs 42 %. Their overall comparison shows a slight
improvement in survival duration but no subset was significantly improved.
The study suffers from many handicaps. The first is the absence of histological
evidence of adenocarcinoma in nearly 50% of cases. Although this is likely to be
equally the case in both time periods, it does raise concerns about the impact on
survival of small numbers of non malignant cases.
Major Revisions
The second is the combination of surgical resected cases with locally advanced
and metastatic disease in most of the analyses.
The authors should first separate gemcitabine use in the adjuvant setting to that
for metastatic and locally advanced disease. The increased use over time needs
to be examined to see if it was equally increased for both indications.
The other key issues are the mixing of inappropriate groups. Since surgery in
Japan is indicated for locally advanced disease that creates issues in
interpretation.
They should examine the outcomes in the two time periods for surgery for cure ie
for stages I, II and III and exclude all IVa surgery cases and then examine the
impact of increased useage of adjuvant chemotherapy - Fig 3 b.
Similarly the authors should specifically only include stages IVa and IVb in their
analysis of the effect of chemotherapy in the two time periods Fig 3 c. This will
eliminate any subgroups of earlier stage, who were not operated on for some
other reason but still given chemotherapy.
Examination of more homogenous groups would enhance the findings of
differences. As it is, there is very little impact of the increased use of gemcitabine
and no understanding as to why the small incremental increase in survival has
occurred. Indeed it is not possible to see in what direction further improvements
might be made with the current analyses.
Over all this type of health service research can provide useful guidance but only
if there is more attention to the comparisons made and those patients included,
to ensure that groups that are most alike are compared for a significant change.
Minor revisions
There are too many figures –
Fig 2 a, 2 c and 2d should just be in the text of the results.
Level of interest: An article whose findings are important to those with closely
related research interests
Quality of written English: Acceptable
Statistical review: No, the manuscript does not need to be seen by a
statistician.
Declaration of competing interests:
I declare I have no competing interests