每天使用阿司匹林会对肿瘤转移产生影响吗？研究人员观察了5组随机试验结果，这5组试验是以使用阿司匹林来降低心血管风险的患者为研究样本，研究样本总共包含17285人。研究人员采用二次分析方法来评估使用阿司匹林对于肿瘤转移的风险性。

在超过6.5年的时间里，阿司匹林显著降低了肿瘤转移的风险性（风险比：0.64，P=.001）。肿瘤的转移在一些常见的受累器官上均有减少，比如肺、肝脏、骨骼、和大脑。但是这一现象仅见于恶性腺瘤患者中，对于其他恶性肿瘤患者，并未出现相同的结果。

    研究人员认为这一现象产生的机制可能与血小板有关，因为阿司匹林可能会抑制血小板的功能。凝血障碍在很多恶性肿瘤中都很常见。他们还指出，在诊断癌症以后停止使用阿司匹林的做法也许是错误的。因为绝大多数癌症患者是死于肿瘤转移造成的疾病，而不是原发病灶。这项研究给我们的一个主要信息是，抑制血小板可能会在控制癌症中起到主要作用。

Effect of daily aspirin on risk of cancer metastasis: a study of incident cancers during randomised controlled trials.

Rothwell PM, Wilson M, Price JF, Belch JF, Meade TW, Mehta Z.
Source
Stroke Prevention Research Unit, Nuffield Department of Clinical Neuroscience, University of Oxford, UK. peter.rothwell@clneuro.ox.ac.uk

Abstract
BACKGROUND:
Daily aspirin reduces the long-term incidence of some adenocarcinomas, but effects on mortality due to some cancers appear after only a few years, suggesting that it might also reduce growth or metastasis. We established the frequency of distant metastasis in patients who developed cancer during trials of daily aspirin versus control.
METHODS:
Our analysis included all five large randomised trials of daily aspirin (≥75 mg daily) versus control for the prevention of vascular events in the UK. Electronic and paper records were reviewed for all patients with incident cancer. The effect of aspirin on risk of metastases at presentation or on subsequent follow-up (including post-trial follow-up of in-trial cancers) was stratified by tumour histology (adenocarcinoma vs other) and clinical characteristics.
FINDINGS:
Of 17,285 trial participants, 987 had a new solid cancer diagnosed during mean in-trial follow-up of 6·5 years (SD 2·0). Allocation to aspirin reduced risk of cancer with distant metastasis (all cancers, hazard ratio [HR] 0·64, 95% CI 0·48-0·84, p=0·001; adenocarcinoma, HR 0·54, 95% CI 0·38-0·77, p=0·0007; other solid cancers, HR 0·82, 95% CI 0·53-1·28, p=0·39), due mainly to a reduction in proportion of adenocarcinomas that had metastatic versus local disease (odds ratio 0·52, 95% CI 0·35-0·75, p=0·0006). Aspirin reduced risk of adenocarcinoma with metastasis at initial diagnosis (HR 0·69, 95% CI 0·50-0·95, p=0·02) and risk of metastasis on subsequent follow-up in patients without metastasis initially (HR 0·45, 95% CI 0·28-0·72, p=0·0009), particularly in patients with colorectal cancer (HR 0·26, 95% CI 0·11-0·57, p=0·0008) and in patients who remained on trial treatment up to or after diagnosis (HR 0·31, 95% CI 0·15-0·62, p=0·0009). Allocation to aspirin reduced death due to cancer in patients who developed adenocarcinoma, particularly in those without metastasis at diagnosis (HR 0·50, 95% CI 0·34-0·74, p=0·0006). Consequently, aspirin reduced the overall risk of fatal adenocarcinoma in the trial populations (HR 0·65, 95% CI 0·53-0·82, p=0·0002), but not the risk of other fatal cancers (HR 1·06, 95% CI 0·84-1·32, p=0·64; difference, p=0·003). Effects were independent of age and sex, but absolute benefit was greatest in smokers. A low-dose, slow-release formulation of aspirin designed to inhibit platelets but to have little systemic bioavailability was as effective as higher doses.
INTERPRETATION:
That aspirin prevents distant metastasis could account for the early reduction in cancer deaths in trials of daily aspirin versus control. This finding suggests that aspirin might help in treatment of some cancers and provides proof of principle for pharmacological intervention specifically to prevent distant metastasis.

原文链接： http://www.ncbi.nlm.nih.gov/pubmed/22440947