In this study, researchers wanted to learn more about the effect of Aspirin taken as low dose (75 - 300 mg) in preventing stomach, colorectal and esophagus cancer. The researchers were interested in the effect by duration of aspirin use and the effect on the time since aspirin intake has been stopped in preventing stomach, colorectal and esophagus cancer. In addition, the study also looked into the time patients survived after being diagnosed (survival rate) with cancer and number of cancer patients who died (case fatality rate). The study was based on an electronic database managed by the Health Authority in Hong Kong containing anonymized clinical information of patients living in Hong Kong.

Inclusion Criteria:

- Received prescription of either low-dose aspirin (75-300 mg) or paracetamol monotherapy during enrolment period.

Exclusion Criteria:

• Received prescription of aspirin monotherapy or combination one year prior to the index date
• Recorded diagnoses of any type of cancer before the index date
• Recorded procedures of colectomy, gastrectomy prior to the index date
• Age < 40 years

Patients aged ≥ 40 years who received low dose aspirin (75-300 mg) or paracetamol between 1st January 2004 and 31st December 2008 will be identified from CDARS (Clinical Data Analysis and Reporting System). CDARS is an electronic clinical database which is managed by the Hospital Authority (HA). More than seven million Hong Kong citizens have access to public healthcare services provided by HA.

Availability of this study's data will be determined according to Bayer's commitment to the EFPIA/PhRMA "Principles for responsible clinical trial data sharing". This pertains to scope, timepoint and process of data access.

As such, Bayer commits to sharing upon request from qualified researchers patient-level clinical trial data, study-level clinical trial data, and protocols from clinical trials in patients for medicines and indications approved in the US and EU as necessary for conducting legitimate research. This applies to data on new medicines and indications that have been approved by the EU and US regulatory agencies on or after January 01, 2014.

Interested researchers can use www.clinicalstudydatarequest.com to request access to anonymized patient-level data and supporting documents from clinical studies to conduct research. Information on the Bayer criteria for listing studies and other relevant information is provided in the Study sponsors section of the portal.