Aspirin for the primary prevention of vascular events?

Aspirin and cancer treatment: systematic reviews and meta-analyses of evidence: for and against

Aspirin as a possible treatment of cancer has been of increasing interest for over 50 years, but the balance of the risks and benefits remains a point of contention. We summarise the valid published evidence 'for' and 'against' the use of aspirin as a cancer treatment and we present what we believe are relevant ethical implications. Reasons for aspirin include the benefits of aspirin taken by patients with cancer upon relevant biological cancer mechanisms. These explain the observed reductions in metastatic cancer and vascular complications in cancer patients. Meta-analyses of 118 observational studies of mortality in cancer patients give evidence consistent with reductions of about 20% in mortality associated with aspirin use. Reasons against aspirin use include increased risk of a gastrointestinal bleed though there appears to be no valid evidence that aspirin is responsible for fatal gastrointestinal bleeding. Few trials have been reported and there are inconsistencies in the results. In conclusion, given the relative safety and the favourable effects of aspirin, its use in cancer seems justified, and ethical implications of this imply that cancer patients should be informed of the present evidence and encouraged to raise the topic with their healthcare team.

Aspirin and cancer: biological mechanisms and clinical outcomes

Evidence on aspirin and cancer comes from two main sources: (1) the effect of aspirin upon biological mechanisms in cancer, and (2) clinical studies of patients with cancer, some of whom take aspirin. A series of systematic literature searches identified published reports relevant to these two sources. The effects of aspirin upon biological mechanisms involved in cancer initiation and growth appear to generate reasonable expectations of effects upon the progress and mortality of cancer. Clinical evidence on aspirin appears overall to be favourable to the use of aspirin, but evidence from randomized trials is limited, and inconsistent. The main body of evidence comes from meta-analyses of observational studies of patients with a wide range of cancers, about 25% of whom were taking aspirin. Heterogeneity is large but, overall, aspirin is associated with increases in survival and reductions in metastatic spread and vascular complications of different cancers. It is important that evaluations of aspirin used as an adjunct cancer treatment are based upon all the available relevant evidence, and there appears to be a marked harmony between the effects of aspirin upon biological mechanisms and upon the clinical progress of cancer.

Aspirin and cancer survival: a systematic review and meta-analyses of 118 observational studies of aspirin and 18 cancers

BACKGROUND

Despite the accumulation of research papers on aspirin and cancer, there is doubt as to whether or not aspirin is an acceptable and effective adjunct treatment of cancer. The results of several randomised trials are awaited, and these should give clear evidence on three common cancers: colon, breast and prostate. The biological effects of aspirin appear likely however to be of relevance to cancer generally, and to metastatic spread, rather than just to one or a few cancers, and there is already a lot of evidence, mainly from observational studies, on the association between aspirin and survival in a wide range of cancers.

AIMS

In order to test the hypothesis that aspirin taking is associated with an increase in the survival of patients with cancer, we conducted a series of systematic literature searches to identify clinical studies of patients with cancer, some of whom took aspirin after having received a diagnosis of cancer.

RESULTS

Three literature searches identified 118 published observational studies in patients with 18 different cancers. Eighty-one studies report on aspirin and cancer mortality and 63 studies report on all-cause mortality. Within a total of about a quarter of a million patients with cancer who reported taking aspirin, representing 20%-25% of the total cohort, we found aspirin to be associated with a reduction of about 20% in cancer deaths (pooled hazard ratio (HR): 0.79; 95% confidence intervals: 0.73, 0.84 in 70 reports and a pooled odds ratio (OR): 0.67; 0.45, 1.00 in 11 reports) with similar reductions in all-cause mortality (HR: 0.80; 0.74, 0.86 in 56 studies and OR: 0.57; 0.36, 0.89 in seven studies). The relative safety of aspirin taking was examined in the studies and the corresponding author of every paper was written to asking for additional information on bleeding. As expected, the frequency of bleeding increased in the patients taking aspirin, but fatal bleeding was rare and no author reported a significant excess in fatal bleeds associated with aspirin. No author mentioned cerebral bleeding in the patients they had followed.

CONCLUSIONS

There is a considerable body of evidence suggestive of about a 20% reduction in mortality in patients with cancer who take aspirin, and the benefit appears not to be restricted to one or a few cancers. Aspirin, therefore, appears to deserve serious consideration as an adjuvant treatment of cancer, and patients with cancer, and their carers, have a right to be informed of the available evidence.

Prophylactic Aspirin and Public

The clinical use of aspirin, first synthesized over 100 years ago, entered a new phase in 1974 with the reporting of the first randomised trial showing a reduction in vascular disease deaths from low-doses. More recent evidence suggests that the medicine is effective against cancer, which makes aspirin of very considerable potential importance to public health improvement and potentially also to clinical practice. It appears that prophylactic aspirin is being increasingly used throughout the community. There is need therefore for the risks and benefits of low-dose aspirin, and its' role within healthcare and within public health, to be widely discussed not least as media reports are bringing this issue into the public domain. It also follows that policy decisions need to be taken as to whether or not its use should be actively promoted. In particular, it is important that Doctors and healthcare practitioners are well informed of the risks and benefits so that they can impart this knowledge during consultations. Furthermore, it is important that low-dose aspirin is not perceived as a substitute for a healthy lifestyle, but that it is recommended and uptake monitored alongside other protective behaviours to improve on health gain, such as smoking cessation, moderate alcohol intake, exercise and diet.

Colorectal cancer prevention: screening and the role of aspirin

SUMMARY Colon cancer is the third most common cancer worldwide. Sigmoidoscopy and colonoscopy, with the removal of rectal and colon polyps, are proven strategies for the prevention of colon cancer, and testing for fecal occult blood helps to identify subjects suitable for endoscopy. Evidence that low-dose aspirin is associated with a substantial reduction in colon cancer risk and reduces the number and growth of colon polyps is accumulating from randomized trials and observational studies. Advantages and disadvantages of endoscopy and aspirin prophylaxis are discussed extensively in this review. The reduction in cancer incidence by the two approaches together is considerably enhanced as they complement each other. Expenditure could become more cost effective if the two were promoted together.

Aspirin minimized the pro-metastasis effect of sorafenib and improved survival by up-regulating HTATIP2 in hepatocellular carcinoma

Background & Aims

We previously demonstrated the pro-metastasis effect of sorafenib in hepatocellular carcinoma (HCC), which is mediated by down-regulation of tumor suppressor HTATIP2. The aim of the present study was to determine whether aspirin minimizes this effect and improves survival.

Methods

The effects of sorafenib, aspirin, and combined sorafenib and aspirin were observed in HCCLM3 and HepG2 xenograft nude mice. Tumor growth, intrahepatic metastasis (IHM), lung metastasis, and survival were assessed. Polymerase chain reaction (PCR) array, real-time (RT)-PCR, and Western blotting were used to examine gene expression. The anti-invasion and anti-metastasis effects of aspirin were studied in HTATIP2-knockdown and HTATIP2-overexpressing HCC cell lines. The molecular mechanism of HTATIP2 regulation by aspirin was explored.

Results

Aspirin suppressed the pro-invasion and pro-metastasis effects of sorafenib in HCC and up-regulated HTATIP2 expression. Aspirin did not inhibit the proliferation of HCC cells, but it decreased the invasiveness of HCC with lower expression of HTATIP2 and increased expression of a set of markers, indicating a mesenchymal-to-epithelial transition in tumor cells. The up-regulation of HTATPI2 expression by aspirin is most likely mediated through inhibition of cyclooxygenase (COX) 2 expression.

Conclusions

Aspirin minimized the pro-metastasis effect of sorafenib by up-regulating the tumor suppressor HTATIP2; this mechanism is mediated through inhibition of COX2.

Aspirin for the older person: report of a meeting at the Royal Society of Medicine, London, 3rd November 2011

On November 23rd 2011, the Aspirin Foundation held a meeting at the Royal Society of Medicine in London to review current thinking on the potential role of aspirin in preventing cardiovascular disease and reducing the risk of cancer in older people. The meeting was supported by Bayer Pharma AG and Novacyl.

Aspirin about 50 years of age for the primary prevention of disease?

Dr Gareth P Morgan FRSPH, Honorary Research Fellow at Cardiff University argues that everyone who has reached their half century could consider taking aspirin

Effect of daily aspirin on long-term risk of death due to cancer: analysis of individual patient data from randomised trials

BACKGROUND

Treatment with daily aspirin for 5 years or longer reduces subsequent risk of colorectal cancer. Several lines of evidence suggest that aspirin might also reduce risk of other cancers, particularly of the gastrointestinal tract, but proof in man is lacking. We studied deaths due to cancer during and after randomised trials of daily aspirin versus control done originally for prevention of vascular events.

METHODS

We used individual patient data from all randomised trials of daily aspirin versus no aspirin with mean duration of scheduled trial treatment of 4 years or longer to determine the effect of allocation to aspirin on risk of cancer death in relation to scheduled duration of trial treatment for gastrointestinal and non-gastrointestinal cancers. In three large UK trials, long-term post-trial follow-up of individual patients was obtained from death certificates and cancer registries.

RESULTS

In eight eligible trials (25 570 patients, 674 cancer deaths), allocation to aspirin reduced death due to cancer (pooled odds ratio [OR] 0·79, 95% CI 0·68-0·92, p=0·003). On analysis of individual patient data, which were available from seven trials (23 535 patients, 657 cancer deaths), benefit was apparent only after 5 years' follow-up (all cancers, hazard ratio [HR] 0·66, 0·50-0·87; gastrointestinal cancers, 0·46, 0·27-0·77; both p=0·003). The 20-year risk of cancer death (1634 deaths in 12 659 patients in three trials) remained lower in the aspirin groups than in the control groups (all solid cancers, HR 0·80, 0·72-0·88, p<0·0001; gastrointestinal cancers, 0·65, 0·54-0·78, p<0·0001), and benefit increased (interaction p=0·01) with scheduled duration of trial treatment (≥7·5 years: all solid cancers, 0·69, 0·54-0·88, p=0·003; gastrointestinal cancers, 0·41, 0·26-0·66, p=0·0001). The latent period before an effect on deaths was about 5 years for oesophageal, pancreatic, brain, and lung cancer, but was more delayed for stomach, colorectal, and prostate cancer. For lung and oesophageal cancer, benefit was confined to adenocarcinomas, and the overall effect on 20-year risk of cancer death was greatest for adenocarcinomas (HR 0·66, 0·56-0·77, p<0·0001). Benefit was unrelated to aspirin dose (75 mg upwards), sex, or smoking, but increased with age-the absolute reduction in 20-year risk of cancer death reaching 7·08% (2·42-11·74) at age 65 years and older.

INTERPRETATION

Daily aspirin reduced deaths due to several common cancers during and after the trials. Benefit increased with duration of treatment and was consistent across the different study populations. These findings have implications for guidelines on use of aspirin and for understanding of carcinogenesis and its susceptibility to drug intervention.

FUNDING

None.