LUGANO, Switzerland, 12 March 2026 – Adherence to Clinical Practice Guidelines in the management of rare cancers remains inconsistent across Europe despite demonstrably improving patient outcomes, shows an analysis jointly conducted by ESMO and EURACAN, the European Reference Network (ERN) for rare cancers. (1) The results, presented today at the ESMO Sarcoma and Rare Cancers Congress 2026, reveal an opportunity for doctors and public health policymakers to improve outcomes by standardising and centralising care for patients with rare malignancies, who taken together represent over 650,000 new cases annually, (2) or a quarter (24%) of all cancer diagnoses in Europe each year. (3)

Delayed diagnosis, limited treatment options, and insufficient research make rare cancers difficult to manage, leading to poorer survival compared to the wider patient population. (4) Developing comprehensive clinical guidelines for these diseases poses inherent challenges due to their low incidence[1] resulting in scarce evidence from randomised clinical trials, a need for cross-border expertise, and reliance on retrospective studies, registries, and expert consensus. Nonetheless, EU-level collaboration through the European Reference Networks has increasingly allowed evidence-based standards to be established, including ESMO-EURACAN Clinical Practice Guidelines in a growing number of rare disease areas.

The recent survey, underlying the previously mentioned analysis, was conducted by EURACAN in September–October 2025, and mapped actual usage of these guidelines throughout the EURACAN network spanning 102 expert healthcare institutions across 25 countries. Uptake was found to be strong overall (over 60%), with most respondents relying on them “always” or “often” across the 10 groups of rare adult solid cancers within EURACAN’s purview. However, the primary purpose for which participants reported referring to clinical guidelines was treatment decision-making, while use for diagnosis, follow-up care and research or teaching purposes was markedly more inconsistent from one clinical domain to another. Utilisation for updating other existing guidelines remained marginal.

A literature review performed in parallel with the survey further validated these observations, revealing that high guideline adherence in expert centres translates into tangible survival benefits, for example, reduced mortality in uterine and soft‑tissue sarcomas, improved outcomes in penile cancer, and better long‑term survival in head and neck cancers. By linking consistent, evidence‑based management to measurable patient gains, the analysis clearly shows how guideline‑concordant care can significantly improve outcomes across a wide spectrum of rare tumour types.

“For ESMO, which is committed to expanding the development of its Clinical Practice Guidelines, the analysis not only confirms the vital importance of clinical guidelines in the management of rare cancers but also highlights the potential to better serve patients by optimising the way they are used by doctors and public health decision-makers,” said Prof. Jean-Yves Blay, Centre Léon Bérard, Lyon, France, and Chair of ESMO's Rare Cancer Working Group. “More than mere clinical decision-making tools, Clinical Practice Guidelines can, and should, serve as quality assurance and standardisation instruments, research references, and resources for continuous update of best practices, particularly crucial for rare cancers”, he added.

ESMO and EURACAN urge national health authorities to build guideline adherence into care pathways by design and help doctors deliver optimal care to patients through the following actions:

• Centralise rare cancer surgeries in accredited centres
• Enforce mandatory multidisciplinary decision-making and time-critical standards throughout patient diagnosis, treatment, and follow-up
• Track adherence to established Clinical Practice Guidelines via national dashboards

At European level, ESMO and EURACAN further recommend strengthening the ERN–EURACAN as an implementation vehicle for equitable access to evidence-based, guideline-concordant care that will be essential to closing the survival gap, both between rare and common cancers, and between EU Member States, and delivering on Europe’s Beating Cancer Plan.

Blay, who was himself involved in the analysis, emphasised: “In rare cancers, where clinical expertise and robust evidence are often limited, well-developed guidelines become a vital instrument to ensure that every patient receives the best possible care. Our findings show that when clinicians follow harmonised, evidence-based recommendations, patient outcomes improve significantly. This underscores the essential role of networks and of the ESMO-EURACAN guidelines in bringing consistency, quality and equity to rare cancer management across Europe.”