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Showing posts with label Paul Moayyedi. Show all posts
Showing posts with label Paul Moayyedi. Show all posts

Tuesday, 7 June 2011

Janusz Jankowski et al comment on Peter Rothwell, Asprin & Cancer, 14 May 2011, The Lancet

reposted from: http://download.thelancet.com/pdfs/journals/lancet/PIIS0140673611606661.pdf?id=e16241398b8eb460:3c68b886:1306b6f6506:38b41307479634423 and Reply:
http://download.thelancet.com/pdfs/journals/lancet/PIIS0140673611606703.pdf?id=e16241398b8eb460:3c68b886:1306b6f6506:38b41307479634423
crabsallover highlightskey pointscomments / links.

Janusz Jankowski, Hugh Barr, John deCaestecker, Peter Watson, Stephen Attwood, Paul Moayyedi


We write with regard to the Article by Peter Rothwell and colleagues,1 which indicates that low-dose aspirin might prevent cancer. Although we strongly endorse Rothwell and colleagues’ publication, we urge caution.

If we presume that aspirin does have a chemoprotective role, it clearly does not work for everyone since at best 25% of people are estimated to get a cancer prevention benefit but this figure could be as low as 20%.

This “aspirin resistance” in patients seems to be present widely in the population so we do not know who should respond.2

Genetic studies such as those undertaken by the Esophageal Adenocarcinoma Genetic Linkage (EAGLE) consortia are needed to assess which individuals will respond best to the chemopreventive eff ects of low dose aspirin.

Additionally, meta-analysis of cardiac trials with reassess ment of causes of cancer deaths might have in advertently introduced bias. For example, the number of cases of gastrointestinal cancer death in Rothwell and colleagues’ study was 182 out of almost 20 000 cases. In particular there were only 23 oesophageal cancers. Patients in these trials, especially those using aspirin, might have had complications that resulted in earlier presentation.

The AspECT chemoprevention trial 3 was specifi cally designed to look at the effect of aspirin on oesophageal cancer development but will also give information on effects on colon cancer development as well as on cardiac deaths. To date, the data monitoring team and the trial steering team have not divulged any obvious trend between the four groups of this trial (low-dose proton-pump inhibitor [PPI], high-dose PPI, low-dose PPI with low-dose aspirin [300 mg], and high-dose PPI with low-dose aspirin). We need trials such as AspECT to report their preliminary findings of genetic stratification for response, as well as risk/benefi t, dose, and length of therapy.

JJ has a consultancy to AstraZeneca Oncology, which makes esomeprazole—one of the agents in the AspECT trial. JJ has also received grants in aid from AstraZeneca previously. All authors are co-investigators in the AspECT trial. *Janusz Jankowski, Hugh Barr, John deCaestecker, Peter Watson, Stephen Attwood, Paul Moayyedi j.a.jankowski@qmul.ac.uk Leicester Royal Infi rmary, Leicester LE7 7HH, UK (JJ, JdC); Gloucestershire Royal Hospital, Gloucester, UK (HB); Belfast Hospital Trust, Belfast, UK (PW); Northumbria Healthcare NHS Foundation Trust, Tyne and Wear, UK (SA); and Gastrointestinal Division, McMaster University Medical Centre, Hamilton, ON, Canada (PM)

1 Rothwell PM, Fowkes FG, Belch JF, Ogawa H, Warlow CP, Meade TW. Eff ect of daily aspirin on long-term risk of death due to cancer: analysis of individual patient data from randomised trials. Lancet 2011; 377: 31–41.
2 Jankowski J, Hunt R. Cyclooxygenase-2 inhibitors in colorectal cancer prevention: better the devil you know. Cancer Epidemiol Biomarkers Prevent 2008; 17: 1858–61.
3 Das D, Chilton AP, Jankowski JA. Chemoprevention of oesophageal cancer and the AspECT trial. Recent Results Cancer Res 2009; 181: 161–69.

Peter Rothwell Reply (full text)  - Risk of GI Bleeds
..
 Mark Nelson raises the issue of the risk of bleeding on aspirin. We deliberately made no specific recommendations about the widespread use of aspirin in healthy individuals, but we did discuss the issue of bleeding in some detail. Our analyses showed that taking aspirin daily for 5—10 years would reduce all-cause mortality (including any fatal bleeds) during that time by about 10% in relative terms. Subsequently, there would be further delayed reductions in risk of cancer death even if aspirin was stopped. In healthy middle-aged individuals, the risk of major bleeding on aspirin is relatively low (about 0·2 per 1000 patients per year—only a small proportion of which are fatal), and is already offset in many groups by the small reduction in risk of ischaemic vascular events. The reduction in risk of cancer is therefore additional to this existing balance in which the bleeding risk is already taken into account. However, the risk of bleeding on aspirin increases steeply with age and so we did not comment on use of aspirin in healthy individuals older than 75 years. The results of the ASPREE trial will be of great importance in this respect. 

Thursday, 23 December 2010

Does long term aspirin prevent cancer? - Moayyedi & Jankowski - full report

reposted from: http://www.bmj.com/content/341/bmj.c7326.full

full article (copy see below) paid for and stored on crabsallover PC: Moayyedi and Jankowski 341bmj-rothwell-aspirin-cancer.pdf. Further, crabsallover reviewed this article here in some depth.

BMJ 2010; 341:c7326 doi: 10.1136/bmj.c7326 (Published 22 December 2010)
Cite this as: BMJ 2010; 341:c7326
  • Editorial

Does long term aspirin prevent cancer?

  1. Paul Moayyedi, professor of medicine1
  2. Janusz A Jankowski, James Black fellow2
+Author Affiliations
  1. 11200 Main Street West, Hamilton, ON, Canada
  2. 2Division of Clinical Pharmacology, Department of Oncology, University of Oxford, Oxford OX3 7DQ, UK
  1. janusz.jankowski@clinpharm.ox.ac.uk
Potentially, but trials specifically designed to answer this question are needed
The cardioprotective effects of aspirin are well established. A meta-analysis of individual subject data from primary prevention randomised controlled trials (RCTs) suggested that aspirin can reduce the relative risk of non-fatal myocardial infarction by about 20%.1 Overall, however, the risks of treatment (severe gastrointestinal and extracranial bleeding) were roughly the same as the benefits, so routine use of aspirin as a primary preventive strategy was not recommended. The meta-analysis did not evaluate any potential reduction of mortality from cancer, as has been suggested by observational data.2 Observational data are difficult to interpret, however, because associations may not be causal and may be the result of confounding or bias.3 Rothwell and colleagues have therefore conducted another meta-analysis of individual subject data from RCTs of aspirin versus no aspirin for prevention of vascular disease, but this time they evaluated mortality from cancer as the main outcome.4 They found a 21% (95% confidence interval 8% to 32%) reduction in the odds of death from cancer in people who took aspirin for almost six years, and the effect was strongest for gastrointestinal cancers. The authors suggest that this may now tip the balance in favour of using aspirin as a primary prevention strategy, both for ischaemic heart disease and cancer.
Figure
Cordelia Molloy/Science Photo Library
The data initially look compelling, and primary care providers could be forgiven for now advising patients above a given age to take aspirin. Recommending widespread use of a drug in an otherwise healthy population, however, needs to be approached cautiously because we need to be certain that the benefits will outweigh the risks.1 A 20% reduction in death from cancer seems impressive, but looking at the data in terms of absolute numbers gives a different story. These trials followed up 25 750 participants for more than 150 000 patient years, and 20 fewer cancers occurred in those taking aspirin compared with those not taking aspirin. Looked at another way, after taking aspirin for almost six years there was a 0.5% absolute reduction in death from cancer, with a number needed to treat of 200 (111 to 1075). Compared with the 50% increase in risk of serious gastrointestinal and extracranial bleeding in participants taking aspirin (overall more than 100 excess serious bleeds occurred in the aspirin group in primary prevention trials),1 it is not clear that the benefits outweigh the risks, even when factoring in the cardioprotective effects of aspirin.
The most rigorous approach to assessing this is to evaluate all cause mortality. To their credit, Rothwell and colleagues analysed this in some detail and report a statistically significant reduction in all cause mortality.4Crucially, the effect is only marginally significant (relative risk of death in the aspirin arm 0.93, 0.87 to 1.00; P=0.045) (figure). This is not particularly robust, especially as six of the eight trials were in subjects at high risk of cardiovascular disease, where the benefits of aspirin should be greatest. Furthermore, the authors included one RCT where the data had been destroyed.5 It could be argued that because they had intended to conduct a meta-analysis of individual participant data this trial should have been excluded. This trial (SAPAT) had the greatest effect on all cause mortality (figure),5 and when it is excluded the results are not significant (0.94, 087 to 1.01; P=0.11). This is corroborated by another meta-analysis of individual participants (95 000 subjects with 660 000 person years of follow-up), which found that aspirin had no significant effect on all cause mortality (0.95, 0.88 to 1.02; P=0.1) when used as primary prevention.1
Figure
Forest plot of all cause mortality in randomised controlled trials of aspirin versus no aspirin4
This last point emphasises the fact that Rothwell and colleagues chose a subset of all the primary and secondary prevention aspirin RCTs that have been conducted. Twenty one RCTs have evaluated about 112 000 subjects,1so Rothwell and colleagues evaluated only around 20% of all subjects. This is because they excluded several trials that did not meet their eligibility criteria (for example, insufficient length of follow-up or subjects given aspirin on alternate days). However, systematic reviews can give different conclusions depending how they are conducted, and eligibility criteria can be somewhat arbitrary.6 For example, Rothwell and colleagues report that 75 mg aspirin a day is sufficient to reduce death from cancer. If this is the case, then perhaps 325 mg every other day would also be effective, as used in the US Physicians Health Study,7 which had 22 071 participants (almost as many as Rothwell and colleagues’ entire meta-analysis). It would be interesting to see how the inclusion of this trial would affect the results.
The data are not robust enough to recommend aspirin for the general population and we still do not know the optimum dose and length of treatment.8 Key data could come from the AspECT trial,9 10 which is evaluating the effect of aspirin in preventing all causes of mortality and oesophageal adenocarcinoma. The interim analysis will be reported in 2012.
In addition, Canada and the United Kingdom have low numbers of gastroenterologists per head of population compared with other countries in the developed world.11 If most of the population started taking aspirin our gastrointestinal services might be overwhelmed. Until further evidence from RCTs is accrued, aspirin should not be recommended for everyone.

Notes

Cite this as: BMJ 2010;340:c7326

Footnotes

  • Competing interests: All authors have completed the Unified Competing Interest form at www.icmje.org/coi_disclosure.pdf (available on request from the corresponding author) and declare: JJ had support for this work from Cancer Research UK, PM had no support; JJ is a consultant for Astrazeneca Oncology and PM and JJ have received Astrazeneca educational grants; JJ is chief investigator and PM is deputy chief investigator of the AspECT trial.
  • Provenance and peer review: Commissioned; not externally peer reviewed.

References