681PDLow-dose aspirin and risk of gastric and oesophageal cancer: A population-based study

Abstract Background Evidence suggests that low-dose aspirin is associated with a 30–40% protective effect against colorectal cancer (CRC) yet its effect on other gastrointestinal cancers has been less studied. We aimed to quantify the association between use of low-dose aspirin and risk of gastric/ oesophageal cancer using a population-based primary care database in the United Kingdom – The Health Improvement Network. Methods Among persons aged 40–89 years from 2005–2015, ∼200,000 new users of low-dose aspirin (75–300 mg/day) were each matched to a non-user by age, sex, time since study entry and number of primary care visits in the previous year. Individuals were followed (max. 18 years) to identify incident cases of gastric/oesophageal cancer. Nested case–control analyses were conducted using 5000 controls for both sets of cancer cases frequency matched by age, sex and calendar year. Adjusted odds ratios (ORs) with 95% confidence intervals (CIs) were calculated for current vs. non-use of low-dose aspirin using logistic regression. Current use was when low-dose aspirin use lasted to 0–90 days before the index date (event date for cases, random date for controls) and total duration of use before the index date was >1 year; non-use was no use of low-dose aspirin ever before the index date or use that ended ≥1 year before the index date. Results We identified 727 incident cases of gastric cancer and 1394 incident cases of oesophageal cancer. As shown in the table, compared with non-use, current use of low-dose aspirin was associated with a significant 54% reduced risk of gastric cancer and a significant 41% reduced risk of oesophageal cancer. Protective effects were seen for both cancers irrespective of total previous duration of low-dose aspirin use. Table . 681PD Odds ratios (95% confidence intervals) for the association between use of low-dose aspirin (current vs non-use) and gastric/oesophageal cancer Gastric cancer Oesophageal cancer Cases N = 727 n (%) Controls N = 5000 n (%) Adjusted OR * (95% CI) Cases N = 1394 n (%) Controls N = 5000 n (%) Adjusted OR * (95% CI) Non-use of low-dose aspirin 442 (60.8) 2404 (48.1) 1.0 (reference) 829 (59.5) 2555 (51.1) 1.0 (reference) Current use of low-dose aspirin (with duration >1 year) 146 (20.1) 1407 (28.1) 0.46 (0.38-0.57) 331 (23.7) 1397 (27.9) 0.59 (0.51-0.69) Duration >1 to  56 (7.7) 693 (13.9) 0.34 (0.25-0.46) 145 (10.4) 680 (13.6) 0.51 (0.41-0.62) Duration > =3 years 90 (12.4) 714 (14.3) 0.60 (0.47-0.77) 186 (13.3) 717 (14.3) 0.68 (0.56-0.82) Remaining current users of low-dose aspirin (i.e. patients with duration 66 (9.1) 730 (14.6) 0.31 (0.23-0.42) 103 (7.4) 625 (12.5) 0.33 (0.26-0.42) Past use of low-dose aspirin (use that ended >90 days before the index date) 73 (10.0) 459 (9.2) 0.61 (0.46-0.80) 131 (9.4) 423 (8.5) 0.65 (0.52-0.81) Duration 34 (4.7) 283 (5.7) 0.42 (0.29-0.62) 65 (4.7) 268 (5.4) 0.49 (0.37-0.67) Duration > =1 year 39 (5.4) 176 (3.5) 0.92 (0.64-1.34) 66 (4.7) 155 (3.1) 0.92 (0.67-1.26) * Adjusted by age, sex and primary care practitioner visits in the year before the index date. Conclusions Our results indicate that use of low-dose aspirin is associated with a significantly reduced risk of gastric and oesophageal cancer as supported by mechanistic data. Editorial acknowledgement Susan Bromley, EpiMed Communications Ltd (Oxford, UK). Legal entity responsible for the study Luis A Garcia Rodriguez. Funding Bayer AG. Disclosure L. Garcia Rodriguez: Honoraria (self), Research grant / Funding (institution), Travel / Accommodation / Expenses: Bayer AG. P. Vora: Full / Part-time employment: Bayer AG. M. Soriano-Gabarro: Full / Part-time employment: Bayer AG. L. Cea Soriano: Research grant / Funding (institution): Bayer AG.