TACTICAL1 Trial Protocol: Targeted Abdominal CT in Conjunction with Lung Cancer Screening to Identify Kidney Cancer and Other Abdominal Conditions: A Randomised Controlled Pilot Study.

Screening for kidney cancer and other serious abdominal conditions in conjunction with lung cancer screening (LCS) is potentially feasible and cost-effective. Targeted Abdominal CT in Conjunction with Lung Cancer Screening (TACTICAL1) aims to pilot this integrated screening model in a real-world setting to inform a future large-scale randomised controlled trial (RCT). TACTICAL1 is a pilot study, with embedded process evaluation, of adding abdominal noncontrast computed tomography (CT; ANCCT) to low-dose CT (LDCT) thorax amongst ever smokers aged 55-70 yr at high risk of lung cancer who were attending the first round of LCS in Yorkshire, UK. There are two points of randomisation. First, participants are randomised 1:1 at the individual level to receive either an LCS invitation letter (invitation control) or an invitation letter for LCS with potential for an additional ANCCT (invitation intervention). Participants in the latter group are then cluster randomised 1:1 to be offered either LDCT thorax alone (scan control) or both LDCT thorax and ANCCT (scan intervention). TACTICAL1 has four primary endpoints and will assess the following: (1) whether the invitation intervention affects LCS uptake, (2) feasibility of cluster randomisation, (3) impact of adding ANCCT to LCS on scanning throughput, and (4) acceptability to participants and screening staff. Strengths include the real-world setting and robust randomisation. TACTICAL1 is a pilot study; therefore, it does not aim to evaluate the prevalence or stage of screen-detected findings nor survival. TACTICAL1 will inform the development of a future large-scale RCT assessing outcomes such as stage shift, earlier detection, and potential survival benefits. A previous study showed that it is possible to offer an additional computed tomography scan of the abdomen at the same time as lung cancer screening. This extra scan may help detect kidney cancer and other serious abdominal conditions early. TACTICAL1 is a pilot research study in which people are randomly assigned to different groups. Its aim is to test how this combined screening approach could work in practice. The results will help design a much larger future study to find out whether combining these scans can save lives.