A primary care intervention to expedite cancer diagnosis: protocol for the ThinkCancer! phase III trial

Five-year cancer survival rates in the United Kingdom (UK) compare poorly with other high-income countries and a comparatively late stage of cancer diagnosis is a key driver. Primary care referrals led to 58.6% of cancer diagnoses in the UK in 2020, making general practice the ideal setting for targeted interventions focusing on improving early cancer diagnosis. ThinkCancer! is an innovative, team-based, theoretically-driven, complex behavioural and educational intervention aimed at reducing primary care cancer diagnostic delays.

The aim of this phase III randomised control trial is to assess the effectiveness and cost-effectiveness of the ThinkCancer! intervention compared with usual primary care. An embedded case note review will characterise patients with the longest intervals to referral.

General practices will be randomised on a 1:1 ratio to either receive the ThinkCancer! Intervention, or to continue with usual care.

Data will be collected from 12 months pre-randomisation to 26 months post-randomisation. Primary outcome measures include the primary care interval (PCI), incremental cost per day reduction in PCI and budget impact of the ThinkCancer!

Secondary outcome measures include referral rates, conversion and detection rates, cancer stage at diagnosis and the guideline interval. A process evaluation will assess intervention implementation. Qualitative interviews will explore patient and carer experiences of urgent suspected cancer referral, and an embedded case note review will explore factors which contribute to the longest primary care intervals for patients with different cancer types.

The trial began in December 2022 with findings expected December 2027.