Key references discussed in the episode:

• Beer TM, et al. Interim results of PATHFINDER, a clinical use study using a methylation-based multi-cancer early detection test. Presented at: American Society of Clinical Oncology Annual Meeting 2021; 4-8 June. Poster 3010
• Liu MC, et al. Ann Oncol. 2020;31(6):745-759. doi: 10.1016/j.annonc.2020.02.011.

Key resources:

• NHS-Galleri trial website
• NHS-Galleri page on GPnotebook

Key take-home points:

• The NHS-Galleri trial represents a screening tool that hopes to identify multiple cancers. In contrast, existing national cancer screening programmes are site-specific (e.g., bowel or cervix).
• The Galleri technology has the potential to identify cancers in the early stages and when asymptomatic.
• If a patient has a positive Galleri test, the positive predictive value for cancer is about 40% (i.e., 40% of patients who have a positive test will have a cancer).
• Based on previous studies, the Galleri tool identifies about 44% of stage I–III cancers. Also, the study design of the NHS-Galleri trial means that 50% of patients recruited will not have the test. The combination of these two facts means that the trial will identify less than a quarter of the stage I-III cancers in the study population.
  • Therefore, GPs who have patients in the study cannot assume that a patient without a positive test does not have cancer and should manage their patients with the usual safety netting.
• Patients involved in the NHS-Galleri trial should be encouraged to continue to partake in national cancer screening programmes.