Chemoprevention of colorectal cancer in individuals with previous colorectal neoplasia: systematic review and network meta-analysis


A wordy title! No wonder patients feel confused when conversing with doctors!

This was the first article that caught my eye in December’s issue of the BMJ:

Chemoprevention of colorectal cancer in individuals with previous colorectal neoplasia: systematic review and  network meta-analysis:

BMJ 2016355 doi: (Published 05 December 2016)Cite this as: BMJ 2016;355:i6188

Meta-analysis is a research method that pools results of similar small studies creating a large body of data from numerous patients – this makes for much more powerful statistics in the right hands. Unfortunately, this paper is very difficult to read and understand. The authors use a lot of abbreviations, acronyms and medical jargon. When I was reviewing papers I would have used a lot of red ink on this one!! This paper looks at patients followed over a 3-5 year period.

Early on in my journey I asked my oncologist what else I should be doing to prevent the tumour returning. Were there some commonly available medicines which might help me? The oncologist mentioned aspirin. Early stage research suggested that aspirin can protect against cancer and possibly its recurrence. However, large randomised trials were not available to give a definitive answer. My oncologist looked at me sidelong while discussing this and tempered his remarks by saying that I was probably at risk of bleeding from the bowel, so on balance best to avoid aspirin.

So, is it possible to prevent colorectal cancer in individuals with a previous history by using some commonly available medicines – NSAIDS or non-steroidal anti-inflammatory drugs (celecoxib and sulindac which are similar to ibuprofen were used in these trials), low and high dose aspirin, calcium and vitamin D, folate? More importantly does the benefit outweigh the risk?

The meta-analysis includes adult patients with previous colorectal neoplasia (i.e. tumours – could be simple or metaplastic polyps or cancer – the paper itself does not specify). Studies were randomised controlled trials of placebo versus an active medication or combination of drugs.

I am unable to reproduce the figures due to copyright but summarising the findings:

NSAIDs were most effective at preventing colorectal cancer but gave most side effects. Of course the most feared side effects of drugs like these (serious side effects are significant but thankfully infrequent) are gastro-intestinal bleeding and kidney failure – so not to be taken lightly.

Aspirin was also very effective especially at the high doses of 160mg. The lower dose 81mg was also effective and had a better track record for side effects.

Calcium supplementation was not very effective and gave a lot of side effects

Folate was not very effective but there were few side effects

Vitamin D was not very effective and there were few side effects. The study doesn’t give the vitamin D doses. One has to delve into the individual referenced papers. The two papers studying vitamin D were quite small and the doses were also rather minute – 20 IU  dailyin Baron et al 2015 and 1000 IU daily in Pommegard et al. 2016. Due to the small numbers of patients given vitamin D alone, I don’t think any real conclusions can be drawn.

Summarising NSAIDs were the most effective but the risks are high. Low dose aspirin had the best risk:benefit profile. However, I don’t feel this paper is sufficiently powered to allow conclusions to be made about calcium, vitamin D or folate.

4 thoughts on “Chemoprevention of colorectal cancer in individuals with previous colorectal neoplasia: systematic review and network meta-analysis

  1. Sian jones

    When i was first told about chemo induced neuropathy i looked into it before i started my chemo.
    I have been taking 600mg of Alpha Lipoic Acid everyday, i am due my last (6th Chemo cycle) and i have not had any symptoms of neuropathy. I will continue to take it after my treatment ends and am looking in to LDN as well.


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