Key references discussed in the episode:
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.