Reviewer's report
Title:Predictive Value of Metabolic 18FDG-PET Response on Outcomes in
Patients with Locally Advanced Pancreatic Carcinoma Treated with Definitive
Concurrent Chemoradiotherapy
Version: 1Date:12 August 2011
Reviewer: Anthony F Shields
Reviewer's report:
The authors have studied the use of 18F-FDG PET (fluorodeoxyglucose positron
emission tomography) for the evaluation of patients with locally advanced
pancreatic carcinoma (LAPC) who are to receive chemoradiotherapy. In this
study they have evaluated the use of PET in staging these patients as well as
assessing treatment response, measured as overall survival, and rate of
resection. They provide some useful data on the use of PET in this group of
patients, but some clarifications are needed.
Minor Essential Revisions
1- When during the 12 weeks post-radiation was PET done? They report that
they gave the gemcitabine on 3 week cycles for 4-6 course or 12-18 weeks. So
were all PETs done at completion or during the gemcitabine?
Major Compulsory Revisions
2- Their division of responding and non-responding patients seems arbitrary.
They said they split patients “response greater versus lesser than the mean
difference.” It is not clear that this is the best division. In fact, they point out that
this divided their patients into 21 patients with a better PET response and 11 with
a poorer response. How about using the median difference, which would divide
these into two equal groups or ROC analysis to pick the cut point?
3- They used the SUVmax as their measure of activity, but this really just
represents a single pixel over the whole tumor. It can be subject to significant
noise. Furthermore, it may be hard to generalize SUVmax from one scanner to
another since the pixel size and resolution can very. Did they also try to use
SUVpeak or some variation of SUVmean? This would be very helpful. Some
investigators have also tried other approaches such as total metabolic volume
(SUV x volume), but this still requires one to set some boundaries on the tumor.
4-The definition of locally advanced and unresectable pancreatic cancer is often
confusing and varies from physician to physician. How did they define it? All they
state is that “Disease extent was determined by radiological studies and
laparoscopy/laparotomy.” What imaging studies were done, e.g did they do CT
with a pancreatic protocol, MRI, EUS? How many patients were judged
unresectable by imaging alone vs at laparotomy?
5-Table 1 should be deleted, since they just give the EORTC PET response
criteria and is not needed in this manuscript. Given the limited number of patients
in the study a table summarizing the results in each patient would be helpful. This
could include the baseline and post-treatment SUV, the PFS and OS and
resection results. This way others could plot and analyze the data as they saw fit.
Level of interest: An article of importance in its field
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 that I have no competing interests.
Reviewer's report
Title:Predictive Value of Metabolic 18FDG-PET Response on Outcomes in
Patients with Locally Advanced Pancreatic Carcinoma Treated with Definitive
Concurrent Chemoradiotherapy
Version: 1Date:12 August 2011
Reviewer: Anthony F Shields
Reviewer's report:
The authors have studied the use of 18F-FDG PET (fluorodeoxyglucose positron
emission tomography) for the evaluation of patients with locally advanced
pancreatic carcinoma (LAPC) who are to receive chemoradiotherapy. In this
study they have evaluated the use of PET in staging these patients as well as
assessing treatment response, measured as overall survival, and rate of
resection. They provide some useful data on the use of PET in this group of
patients, but some clarifications are needed.
Minor Essential Revisions
1- When during the 12 weeks post-radiation was PET done? They report that
they gave the gemcitabine on 3 week cycles for 4-6 course or 12-18 weeks. So
were all PETs done at completion or during the gemcitabine?
Major Compulsory Revisions
2- Their division of responding and non-responding patients seems arbitrary.
They said they split patients “response greater versus lesser than the mean
difference.” It is not clear that this is the best division. In fact, they point out that
this divided their patients into 21 patients with a better PET response and 11 with
a poorer response. How about using the median difference, which would divide
these into two equal groups or ROC analysis to pick the cut point?
3- They used the SUVmax as their measure of activity, but this really just
represents a single pixel over the whole tumor. It can be subject to significant
noise. Furthermore, it may be hard to generalize SUVmax from one scanner to
another since the pixel size and resolution can very. Did they also try to use
SUVpeak or some variation of SUVmean? This would be very helpful. Some
investigators have also tried other approaches such as total metabolic volume
(SUV x volume), but this still requires one to set some boundaries on the tumor.
4-The definition of locally advanced and unresectable pancreatic cancer is often
confusing and varies from physician to physician. How did they define it? All they
state is that “Disease extent was determined by radiological studies and
laparoscopy/laparotomy.” What imaging studies were done, e.g did they do CT
with a pancreatic protocol, MRI, EUS? How many patients were judged
unresectable by imaging alone vs at laparotomy?
5-Table 1 should be deleted, since they just give the EORTC PET response
criteria and is not needed in this manuscript. Given the limited number of patients
in the study a table summarizing the results in each patient would be helpful. This
could include the baseline and post-treatment SUV, the PFS and OS and
resection results. This way others could plot and analyze the data as they saw fit.
Level of interest: An article of importance in its field
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 that I have no competing interests.
Please review this paper.
user
Reviewer's report
Title:Predictive Value of Metabolic 18FDG-PET Response on Outcomes in
Patients with Locally Advanced Pancreatic Carcinoma Treated with Definitive
Concurrent Chemoradiotherapy
Version: 1Date:12 August 2011
Reviewer: Anthony F Shields
Reviewer's report:
The authors have studied the use of 18F-FDG PET (fluorodeoxyglucose positron
emission tomography) for the evaluation of patients with locally advanced
pancreatic carcinoma (LAPC) who are to receive chemoradiotherapy. In this
study they have evaluated the use of PET in staging these patients as well as
assessing treatment response, measured as overall survival, and rate of
resection. They provide some useful data on the use of PET in this group of
patients, but some clarifications are needed.
Minor Essential Revisions
1- When during the 12 weeks post-radiation was PET done? They report that
they gave the gemcitabine on 3 week cycles for 4-6 course or 12-18 weeks. So
were all PETs done at completion or during the gemcitabine?
Major Compulsory Revisions
2- Their division of responding and non-responding patients seems arbitrary.
They said they split patients “response greater versus lesser than the mean
difference.” It is not clear that this is the best division. In fact, they point out that
this divided their patients into 21 patients with a better PET response and 11 with
a poorer response. How about using the median difference, which would divide
these into two equal groups or ROC analysis to pick the cut point?
3- They used the SUVmax as their measure of activity, but this really just
represents a single pixel over the whole tumor. It can be subject to significant
noise. Furthermore, it may be hard to generalize SUVmax from one scanner to
another since the pixel size and resolution can very. Did they also try to use
SUVpeak or some variation of SUVmean? This would be very helpful. Some
investigators have also tried other approaches such as total metabolic volume
(SUV x volume), but this still requires one to set some boundaries on the tumor.
4-The definition of locally advanced and unresectable pancreatic cancer is often
confusing and varies from physician to physician. How did they define it? All they
state is that “Disease extent was determined by radiological studies and
laparoscopy/laparotomy.” What imaging studies were done, e.g did they do CT
with a pancreatic protocol, MRI, EUS? How many patients were judged
unresectable by imaging alone vs at laparotomy?
5-Table 1 should be deleted, since they just give the EORTC PET response
criteria and is not needed in this manuscript. Given the limited number of patients
in the study a table summarizing the results in each patient would be helpful. This
could include the baseline and post-treatment SUV, the PFS and OS and
resection results. This way others could plot and analyze the data as they saw fit.
Level of interest: An article of importance in its field
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 that I have no competing interests.
assistant