Aspirin use after radical cancer therapy – feasibility and toxicity data from the Add-Aspirin trial
Session type: Poster / e-Poster / Silent Theatre session
Pre-clinical, observational and randomised evidence suggests aspirin may prevent or delay the development of cancer and metastases, and is strongest for colorectal and gastro-oesophageal cancer. However, concerns around feasibility, adherence and tolerability (particularly serious bleeding) have limited aspirin use for cancer chemoprevention.
Add-Aspirin is a double-blind, randomised-controlled trial encompassing 4 individually powered phase III trials in early-stage breast, prostate, colorectal and gastro-oesophageal cancer, evaluating the effect of aspirin after radical therapy. All participants initially take open-label aspirin (100mg daily) for 8 weeks (run-in), to assess adherence and toxicity prior to randomisation (1:1:1, aspirin 300mg, aspirin 100mg or matched placebo for ≥5 years). A pre-planned feasibility analysis was performed to assess tolerability and adherence when >2000 participants had completed the run-in period.
Between October 2015 and October 2017, 3494 of a targeted 11000 participants were registered from 165 sites in the UK; recruitment rates differed across tumour sites compared to predictions. Run-in data (n=2253) showed good adherence: 95% took 6-7 tablets/week and 85% proceeded to randomisation, with rates consistent across tumour cohorts. Main reasons for not proceeding to randomisation were toxicity (mostly minor, grade 1/2) and/or patient choice, with only 0.7% (16/2253) of participants experiencing toxicity requiring discontinuation during the run-in. Fewer than 1% (13/2253) experienced a grade > 3 toxicity (including one lower gastrointestinal bleed in a prostate cancer participant; no upper gastrointestinal bleeds).
The data demonstrate that aspirin is well-tolerated over an 8-week run-in, and acceptable to patients after radical cancer therapy, with low toxicity rates in all tumour cohorts, including gastro-oesophageal participants. A run-in approach may be useful in adjuvant (or prevention) studies for reducing the risk of non-adherence and participant attrition at a later date. Trial recruitment continues with >5000 participants now registered from the UK and India.