Review for 10.1186/1471-230X-9-60 (2009)

Reviewer's report
Title:Physical Activity and Diet Behaviour in Colorectal Cancer Patients
Receiving Chemotherapy: Associations with Quality of Life
Version: 1Date:1 July 2009
Reviewer: Kristina H Karvinen
Reviewer's report:
This is a well-written paper examining relationships between physical activity,
diet and quality of life in on-treatment colorectal cancer survivors. The findings
provide a novel insight into these relationships in a previously unexamined
sub-population of colorectal cancer patients.
Major Compulsory Revisions
1. One of my major concerns with this manuscript is the “Exploratory Analyses”
on page
12. The authors claim that since such a low percentage of participants (26.2%)
were meeting physical activity guidelines, they would examine relationships
between a new definition of physical activity (i.e., any activity at all) and quality of
life. This seems strange. First of all, 26.2% does not seem like a low percentage
meeting physical activity guidelines when compared to other studies of cancer
survivors and the general population. In fact, I would argue that 26.2% is high
considering this sample is currently on chemotherapy. Second, I fail to
understand what the advantage is of examining a category of physical activity
that encompasses anywhere from 15 minutes of mild physical activity a week
upward to heavy, regular physical activity. At this point there isn’t any evidence
that suggests that 15 minutes of mild physical activity has any health or QOL
benefits. My suggestion would be to completely remove this section. In a larger
sample size, three categories of activity could be examined (i.e., meeting
physical activity guidelines, some moderate-to-vigorous activity but not sufficient
to meet guidelines, no moderate-to-vigorous activity), but I think with such a
small sample size this kind of analysis would be underpowered.
2. Another concern is the interpretation of the physical activity results on pages
13-14.
The authors claim that because few participants were meeting physical activity
guidelines, they must be inappropriate for CRC survivors on chemotherapy. This
doesn’t make any sense. The percentage of the regular population meeting
public health recommendations for exercise is also relatively low, yet it would be
ridiculous to conclude that this is the case because the recommendations are too
high. The guidelines are there because we know from research studies that that
is the minimal amount of activity that is required for health benefits. It is possible
that these guidelines are in fact inappropriate for CRC survivors on
chemotherapy, but at this point we do not know what the optimal volume is for
this population. Certainly it cannot be ascertained by examining the percentage
of people that actually meet that goal. The authors should remove these
statements from the discussion.
Minor Essential Revisions
1. Page 2 (Abstract) – The latter part of the first sentence is inaccurate. I don’t
think you
are referring to the role of QOL in the relationship between CRC risk and physical
activity.
2. Page 2 (Abstract) – The purpose statement is not entirely in line with the
purpose in the
main body of the text. Mention secondary purposes since they are discussed in
the conclusion.
3. Page 10 (Results) – Under “Quality of Life and Social Support” , an
interpretation of
means scores is provided. All interpretations of data should be in the discussion
section.
4. Page 11 (Results) – Second paragraph – “The data revealed that BMI was
negatively
correlated with QOL, and age, total social support…were positively associated”.
Is a bit misleading. It sounds like the latter variables are associated with BMI.
5. Page 11 (Results) – Last paragraph – The first sentence reads that “Individual
t-tests
were used to determine the significance between groups…” It might help to
clarify exactly what the groups are.
6. Page 12 (Results) – First paragraph – This paragraph seems redundant to the
results in
the first paragraph on page 11.
7. Page 13 (Discussion) – First paragraph – “Specifically, diet behaviour, ….was
better
achieved in this sample than physical activity” This state is confusing. It would
make more sense to say “meeting dietary guidelines”.
8. Page 13 (Discussion) – Last full paragraph – Indicating that because 85% of
the
sample was meeting recommendations for fruit and vegetable intake “may also
suggest that current diet guidelines are reasonable for survivors undergoing
adjuvant or metastatic chemotherapy” doesn’t make any logical sense. We could
just as well say that just because 85% of a population eats fast food on a daily
basis we should incorporate that into their dietary guidelines since it is feasible
for them. These kind of statements should be removed.
9. Page 14 (Discussion) – Last paragraph – The authors state that the
percentage of CRC
survivors in previous studies that meet physical activity guidelines is “low”, yet
the range is from 25-54%. These percentages do not seem particularly low, in
fact they could be considered comparable to the general age-matched
population.
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 that I have no competing interests.