The news at a glance
- This study was in people with bowel cancer (that had not spread to distant parts of the body) whose tumour had a particular genetic change called PI3K [1].
- After treatment, half of the patients took one low-dose aspirin tablet (160 mg) a day for 3 years and half took a dummy tablet [1].
- With aspirin, the chance of the cancer coming back within 3 years was almost halved [1].
- About a third of bowel tumours have this change; finding it needs a genetic test on a sample of the tumour [1].
- Overall survival: how long patients lived.
- Progression-free survival: how long the disease did not get worse.
- Disease-free or event-free survival: how long the disease did not come back after treatment.
- Median: the number that half of patients were above and half below; for example, "a median of 10 months" means that in half of patients the disease stayed under control for at least 10 months.
- Phase 3: a large, careful study comparing a new drug with the usual treatment; the basis of most approvals.
Talk to your doctor about what this result means for you.
What was reported?
For physicians
Aspirin reduces the incidence of polyps and colorectal cancer in high-risk people, and observational studies had shown that regular aspirin use after diagnosis is associated with better survival, especially in tumours with PIK3CA mutations [1, 2]. For example, in an important observational study in 2012, aspirin use after diagnosis was associated with lower cancer-specific mortality only in patients with PIK3CA mutations [2]. But before ALASCCA, there was no randomised trial in this setting [1].
In the double-blind, placebo-controlled ALASCCA trial, patients with stage I to III rectal cancer or stage II or III colon cancer whose tumours had somatic alterations in PI3K pathway genes were randomised 1:1 to aspirin 160 mg or placebo daily for 3 years [1]. PI3K pathway alterations were found in 1,103 of 2,980 patients (37.0%), and 626 patients were randomised [1].
In group A (PIK3CA hotspot mutations in exon 9 or 20), the 3-year cumulative incidence of recurrence was 7.7% with aspirin and 14.1% with placebo. In group B (other PIK3CA, PIK3R1 or PTEN alterations) the figures were 7.7% and 16.8% [1].
What does this finding mean for patients?
If you have bowel cancer that has not spread to distant parts of the body, ask your doctor whether a genetic test of your tumour for PI3K pathway changes (such as PIK3CA) has been done or could be done for you. In this study, low-dose aspirin almost halved the risk of the cancer coming back in patients with these changes [1]. Do not start aspirin on your own: aspirin can cause bleeding, and in this study serious side effects were slightly more common in the aspirin group [1]. The decision should be made with your treating doctor.
Trial details and regimen (for physicians)
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- The primary endpoint was significant only in group A (PIK3CA exon 9/20 hotspot mutations); the group B result is a secondary endpoint [1].
- 3-year disease-free survival in group A was 88.5% vs 81.4% and did not reach statistical significance (HR 0.61; 95% CI 0.34 to 1.08) [1].
- Severe adverse events occurred in 16.8% of aspirin recipients and 11.6% of the placebo group; assess contraindications and bleeding risk [1].
- In a population-based study with routine genomic testing, the prevalence of PIK3CA/PTEN alterations was 14.6% (lower than the 37% in ALASCCA), and about 11% of all patients were identified as potentially eligible for aspirin [4].
- The Western Canadian Gastrointestinal Cancer Consensus Conference (2025) considered adjuvant aspirin and PI3K testing based on ALASCCA in its recommendations [5].
ALASCCA trial regimen
Low-dose adjuvant aspirin
Stage I to III rectal cancer or stage II to III colon cancer after radical surgery, with somatic PI3K pathway alterations (PIK3CA, PIK3R1 or PTEN); off-label useCycle length: Daily, continuous
Stage I to III rectal cancer or stage II to III colon cancer after radical surgery, with somatic PI3K pathway alterations (PIK3CA, PIK3R1 or PTEN); off-label use
| Drug | Dose | Route | Schedule |
|---|---|---|---|
| Aspirin (acetylsalicylic acid) | 160 mg | Oral | Once daily |
Key protocol criteria: platelets 100×10⁹/L or higher; a clear colonoscopy or CT colonography within 3 months before or after surgery. Exclusion criteria: Lynch syndrome or familial polyposis, a bleeding disorder, concomitant antiplatelet or anticoagulant use (postoperative low-molecular-weight heparin must be stopped before starting), active gastritis or peptic ulcer or significant postoperative bleeding in the past 3 months, regular corticosteroid or NSAID use, aspirin allergy, pregnancy or breastfeeding [6, 1].
Evidence: ALASCCA (2025)
Doses follow the trial protocol, guideline or official drug label (source given in the notes of each regimen). Before prescribing, check blood counts, renal and hepatic function, drug interactions and the patient’s condition, and adjust the dose according to the drug label.
Limitations and next steps
- The number of events is small and the confidence intervals are wide; the group A hazard ratio was at the borderline of statistical significance [1].
- Overall survival data are not yet mature enough to draw conclusions, and the study was done in the Nordic countries [1].
- This use of aspirin is not on the drug label and requires genetic testing of the tumour [1, 4].
Main study
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Key study
1 itemLow-Dose Aspirin for PI3K-Altered Localized Colorectal Cancer
References
6 referencesShow all references, 5 with a study cardClose the reference list
Numbers in the text, such as [1], refer to these sources. Sources with a “Study card” button are summarised in the site’s evidence library.
- 1
- 2Aspirin Use, Tumor PIK3CA Mutation, and Colorectal-Cancer Survival
- 3ALASCCA: an aspirin a day keeps colorectal cancer away
- 4
- 5Report from the 27th Annual Western Canadian Gastrointestinal Cancer Consensus Conference on Colorectal Cancer, Calgary, Alberta, 26–27 September 2025: Advances in Colon and Rectal Cancer
- 6Adjuvant Low Dose Aspirin in Colorectal Cancer (ALASCCA) (NCT02647099)
This page is based on reputable scientific sources and was last updated on 28 October 2026. The content of this website is for educational and informational purposes only and does not replace consultation, diagnosis or treatment by a specialist physician. Consult your treating physician about any treatment decision.
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