Lancet Oncology's AI Policy: More Restrictive Than JCO, JAMA Oncology, and Most Competitors

Permitted at Lancet Oncology:

• Fixing grammar and spelling in a paragraph you wrote
• Restructuring a complex sentence into two clearer ones
• Improving flow between paragraphs you drafted
• Translating from your native language to English, then polishing

Not permitted (but allowed at JCO or JAMA Oncology):

• Asking AI to draft a paragraph explaining the Cox proportional hazards model you used
• Having AI generate a summary of clinical trials for your introduction
• Using AI to write a first draft of a discussion section from bullet points
• Asking AI to compose responses to reviewer comments

This is a meaningful difference. At JCO, you could ask ChatGPT to help you draft a Methods paragraph about your statistical approach, disclose it, and be compliant. At Lancet Oncology, that same use would violate the policy. The content must come from you; AI can only clean it up.

Lancet Oncology is published by Elsevier, but the Lancet family applies a stricter interpretation:

If you've submitted to other Elsevier journals and used AI for broader writing assistance, be aware that the same approach won't be compliant at Lancet Oncology. The Lancet family operates under different rules than the wider Elsevier portfolio.

Phase III clinical trial reports. Lancet Oncology publishes some of the most consequential Phase III oncology trials in the world. These papers, reporting overall survival results for checkpoint inhibitors, progression-free survival for targeted therapies, quality of life outcomes for novel combinations, change oncology practice within weeks of publication. NCCN guidelines get updated based on Lancet Oncology publications. ESMO guidelines reference them. Tumor boards discuss them. AI involvement in interpreting hazard ratios, characterizing adverse event profiles, drawing efficacy conclusions, or formulating treatment recommendations would undermine the clinical authority that makes these papers influential. Use AI to fix your grammar. Don't use it to help you decide whether your trial showed clinically meaningful benefit.

Biomarker and companion diagnostic studies. PD-L1 expression cutoffs, TMB thresholds, ctDNA-based monitoring, these directly affect which patients get which treatments. AI involvement in interpreting biomarker performance characteristics (sensitivity, specificity, predictive values) or in setting clinical cutoffs would be problematic. If your paper uses machine learning to develop a biomarker classifier, that's research AI, described in standard Methods. If you also used Claude to edit your Discussion, that's writing AI, disclosed in acknowledgments. Keep them strictly separate.

Cancer epidemiology studies. Large population-based cancer studies involve complex datasets: SEER, cancer registries, claims databases. If AI coding tools helped you write the scripts to query these databases, disclose it. But the clinical interpretation of incidence trends, survival patterns, and risk factor associations must come from the epidemiologists on the team.

Systematic reviews and meta-analyses. Lancet Oncology publishes influential systematic reviews that synthesize evidence for clinical questions. The "readability and language" limitation means you can use AI to improve the prose of your completed review. You can't use it to help screen abstracts, extract data, or synthesize findings, those are content generation activities that fall outside the permitted scope.

Remember: at Lancet Oncology, disclosure goes in acknowledgments, not Methods.

Phase III trial: "The authors used ChatGPT (GPT-4, OpenAI) to improve the readability and English language of the Introduction section. No AI tools were involved in trial design, data management, statistical analysis, efficacy assessment, safety evaluation, or interpretation of clinical outcomes. All clinical conclusions were drawn by the study investigators. The authors take full responsibility for the published content."

Biomarker study: "Claude (Claude 3.5, Anthropic) was used to improve the readability of the Discussion section. No AI tools were used in biomarker assay development, statistical analysis, cutoff determination, or clinical interpretation. The authors take full responsibility for the published content."

Epidemiology study: "During the preparation of this manuscript, the authors used ChatGPT (GPT-4o, OpenAI) to improve the clarity of the Results and Discussion sections. GitHub Copilot (Microsoft) assisted with writing SAS scripts for database queries. All scripts were validated by the study biostatistician (E.F.). No AI tools were involved in the interpretation of epidemiologic findings. The authors take full responsibility for the published content."

Systematic review/meta-analysis: "The authors used Claude (Claude 3.5, Anthropic) to improve the language and readability of selected sections of the manuscript. The systematic search, study selection, data extraction, risk of bias assessment, meta-analysis, and evidence grading were performed entirely by the author team without AI assistance. The authors take full responsibility for the published content."

Notice that these disclosures are placed in the acknowledgments section, not Methods. This is easy to get wrong if you've been submitting to JCO or JAMA Oncology, where the disclosure goes in Methods. If a Lancet Oncology editor sees an AI disclosure in your Methods section instead of acknowledgments, they'll ask you to move it, not a major problem, but it signals that you didn't read their specific instructions.

Lancet Oncology is the only top-five clinical oncology journal that restricts AI to readability and language only. JCO is the closest comparison, both compete for the same high-impact trial papers, but an author who used AI to draft a Methods section would be compliant at JCO and non-compliant at Lancet Oncology. The two journals also differ on disclosure placement: Methods (JCO) versus acknowledgments (Lancet Oncology).

Annals of Oncology shares Elsevier as a publisher but follows ESMO's interpretation, which is closer to the Elsevier general policy than to the Lancet's restrictive stance. Cancer Discovery follows AACR's moderate approach, permitting writing assistance with disclosure.

The Lancet family takes AI disclosure seriously. The Lancet Research Integrity Group (est. 2024) handles AI-related concerns with clinical oncology expertise, editors with clinical and scientific backgrounds who can assess whether AI involvement actually compromised the science or was limited to language polishing.

During peer review: If a reviewer or editor suspects undisclosed AI use, the corresponding author receives a direct inquiry. Given Lancet Oncology's 95%+ desk rejection rate, papers that survive to external review are already under intense scrutiny.

After publication, the escalation: correction (permanently linked to your paper in PubMed), expression of concern, or retraction. For trial reports that influence treatment guidelines, a retraction would likely trigger guideline reassessment by NCCN, ESMO, or other bodies that cited the work. In serious cases involving clinical trial reports, the journal may notify the authors' institution. The clinical weight of Lancet Oncology publications amplifies every consequence.

Respect the boundary. If you're unsure whether your AI use crosses from "readability and language" into "content generation," it probably does. The safe rule: write everything yourself first, then use AI only to clean up the language. If you can't point to a human-written draft that preceded the AI interaction, you've likely crossed the line.

Prepare two disclosure versions. If you're submitting to Lancet Oncology but have JCO or Annals of Oncology as backup targets, prepare two disclosure statements: one for the acknowledgments (Lancet Oncology) and one for Methods (JCO/Annals). It's a small effort that saves time if you need to redirect your submission.

Mention AI in the cover letter. While the formal disclosure goes in acknowledgments, mentioning AI use in the cover letter is good practice for Lancet Oncology submissions. Proactive transparency signals that you take the policy seriously.

Watch for co-author AI use. If a co-author used AI to draft their section rather than just edit it, that's a problem under Lancet Oncology's rules even if it would be fine at JCO. The corresponding author needs to verify that all co-authors' AI use falls within the "readability and language" scope, not just that they used AI.