We Were Wrong About Aspirin (New Evidence)

Why It Matters

The reversal of aspirin’s cancer‑prevention claim reshapes prescribing practices, preventing unnecessary harm to millions of older adults while preserving its proven cardiovascular benefits for those who need it.

Key Takeaways

• Aspirin's primary‑prevention cancer benefit disproved in elderly trials
• Older adults on low‑dose aspirin faced 15% higher cancer mortality
• Benefit seen only in younger, high‑dose, genetically‑high‑risk groups
• Guidelines withdrew routine aspirin for cancer prevention after 2022
• Patients should keep aspirin only for confirmed cardiovascular secondary prevention

Summary

The video examines how new randomized evidence overturns the long‑standing belief that daily low‑dose aspirin prevents cancer in otherwise healthy adults. Early observational studies and a 2010 meta‑analysis by Peter Rothwell suggested a one‑third reduction in cancer deaths, prompting the US Preventive Services Task Force to recommend aspirin for primary colorectal cancer prevention in people aged 50‑59.

Subsequent large‑scale trials, especially the ASPREE study of 19,114 adults over 70, found no reduction in cancer incidence and a 15% increase in cancer mortality among aspirin users. A later 2026 JAMA Oncology analysis confirmed these findings, and a Cochrane review of ten trials reported a 77% rise in colorectal cancer deaths within five‑to‑ten years of use, casting serious doubt on the earlier optimism.

The video highlights contrasting data: while ASPREE showed harm in older adults on 100 mg, a separate CAP2 trial demonstrated a 35% drop in colorectal cancer for Lynch‑syndrome carriers taking 600 mg at a median age of 45. Mechanistic research from Cambridge also showed aspirin can block platelet‑derived thromboxane A2, theoretically enhancing immune clearance of metastases—yet this benefit may not translate in aged immune systems.

The practical takeaway is clear: aspirin should no longer be prescribed for primary cancer prevention in the general older population, and clinicians must limit its use to proven secondary cardiovascular indications. Personalized dosing, age considerations, and genetic risk factors will shape future recommendations.

Original Description

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Timestamps:

00:00 Aspirin's Initial Success

01:59 Aspirin's Impact on Cancer

03:26 The Unexpected Twist: John McNeill's Observations

00:04:33 The ASPREE Trial

06:12 The Follow-up ASPREE Results

08:05 The Updated Analysis by the Cochrane Library

13:32 The Current State of Aspirin Use

Here are the links to the research papers referenced in the video:

Rothwell — Daily aspirin and long-term cancer death (Lancet, 2011)

https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(10)62110-1/abstract

USPSTF 2016 — Aspirin for CVD and colorectal cancer prevention

https://www.uspreventiveservicestaskforce.org/uspstf/recommendation/aspirin-to-prevent-cardiovascular-disease-and-cancer-april-2016

McNeil — ASPREE: aspirin and all-cause mortality (NEJM, 2018)

https://www.nejm.org/doi/10.1056/NEJMoa1803955

Kune — Melbourne Colorectal Cancer Study (1988)

https://pubmed.ncbi.nlm.nih.gov/3390835/

Burn — CAPP2 aspirin in Lynch syndrome, 10-year follow-up (Lancet, 2020)

https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(20)30366-4/fulltext

Rothwell — Aspirin and cancer metastasis (Lancet, 2012)

https://pubmed.ncbi.nlm.nih.gov/22440947/

Rothwell — Aspirin short-term cancer incidence and mortality, 51 RCTs (Lancet, 2012)

https://pubmed.ncbi.nlm.nih.gov/22440946/

ASPREE recruitment — lessons from a 19,114-person GP-led trial

https://pmc.ncbi.nlm.nih.gov/articles/PMC6456041/

ASPREE — aspirin, cardiovascular events and bleeding (NEJM, 2018)

https://www.nejm.org/doi/10.1056/NEJMoa1805819

Orchard — ASPREE follow-up: cancer incidence and mortality (JAMA Oncology, 2026)

https://jamanetwork.com/journals/jamaoncology/article-abstract/2844193

Healio — Orchard interview on the ASPREE follow-up

https://www.healio.com/news/hematology-oncology/20260218/lowdose-aspirin-significantly-increases-cancer-mortality-risk-among-older-adults

Cai — Cochrane review: aspirin and NSAIDs for colorectal cancer prevention (2026)

https://www.cochranelibrary.com/cdsr/doi/10.1002/14651858.CD015266.pub2/full

USPSTF 2022 — Aspirin for CVD prevention (colorectal cancer withdrawn)

https://jamanetwork.com/journals/jama/fullarticle/2791399

University of Cambridge press release — how aspirin could prevent metastasis

https://www.cam.ac.uk/research/news/scientists-discover-how-aspirin-could-prevent-some-cancers-from-spreading

Yang — Aspirin prevents metastasis via platelet TXA2 and T cell immunity (Nature, 2025)

https://www.nature.com/articles/s41586-025-08626-7

McNeil — Aspirin and cancer incidence/mortality in older adults (JNCI, 2021)

https://academic.oup.com/jnci/article/113/3/258/5889955

Lynch syndrome — physician compliance and patient uptake with aspirin therapy (2026)

https://pubmed.ncbi.nlm.nih.gov/41661407/

Thumbnail by James Kelly

Video edited by Troy Young

Script by John Milliken

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