The ASAC trial is a Scandinavian, multi-center, double-blinded, randomized, placebo-controlled study to determine whether adjuvant treatment with low-dose acetylsalicylic acid (ASA) can improve disease free survival in patients treated with resection for colorectal cancer liver metastases (CRCLM). Several studies have shown beneficial effect of ASA on primary prevention of CRC and our group and others have shown a potential association of ASA also taken after the diagnosis on CRC survival in registry-based studies (secondary prevention). Up to 800 patients operated for CRCLM will be randomized to Arm#1 ASA 160 mg once daily or Arm#2 Placebo for a period of 3 years or till disease recurrence. The patients will be treated and followed up according to standard of care and the National Guidelines.


The ASAC trial will be the first clinical interventional trial to assess the beneficial role of ASA in recurrence of CRC liver metastases and survival. ASA is an inexpensive, well tolerated, and easily accessible drug that will be highly potential as adjuvant drug in secondary prevention of CRC liver metastases if the study shows a beneficial effect. We will also determine the effect of ASA as adjuvant treatment on Health-related Quality of Life and the cost-effectiveness.


The trial is initiated by Oslo University Hospital and University of Oslo, Norway and is funded by The Norwegian Research Council, The Norwegian Cancer Society, and KLINBEFORSK. The study will be recruiting patients in Norway, Sweden and Denmark at all major HPB surgical units. Identifier: NCT03326791

Study flow chart



Inclusion criteria

Colorectal liver metastases (CRCLM)
Primary tumor removed
Macroscopic surgical free resection margins
Performance status ECOG 0-2
Age 18 years or above

Exclusion criteria

Concomitant use of ASA or other anticoagulants or platelet inhibitors such as warfarin or klopidogrel
Regular use of corticosteroids or NSAIDs
Inherited or acquired coagulopathy (haemophilia)
Blood platelets < 100 x 10^9/L