The Reality Check on 'Everything' Cancer Tests: No Single Solution Exists

A recent conversation with a guest at an academic function brought to light the public's desire for a simple, all-encompassing test for cancer. The guest, intrigued by the speaker's profession as an oncologist, inquired about the existence of an 'everything' test for cancer. The speaker's response was clear: no such test exists.

The quest for early cancer detection is a significant goal in cancer medicine, with the aim of identifying the disease before it metastasizes and ensuring a cure. One company, Grail, launched a blood test called Galleri, which claims to detect a 'signal' shared by more than 50 types of cancer. This signal is identified through circulating DNA, minute fragments of cancer DNA present in the bloodstream.

The Galleri test was marketed as a screening tool, with results indicating either a cancer signal detected or no cancer signal detected. However, the test failed to meet its primary endpoint in a large-scale trial conducted with the NHS, which aimed to determine if the test could reduce late-stage cancer diagnoses. Despite the company's claims of 'strong' results, the trial did not demonstrate a significant reduction in late-stage cancer diagnoses.

The failure of the Galleri test highlights a crucial distinction between detecting more cancers and saving lives. Detecting cancer at an early stage does not necessarily translate to less invasive treatments or prolonged survival. Moreover, some cancers detected through screening may never have posed a lethal threat, leading to unnecessary interventions.

For now, there is no blood test or total body scan that saves lives. Instead, the focus should be on modifying cancer risk factors, such as reducing processed foods, curbing alcohol consumption, quitting smoking, and engaging in regular exercise. These evidence-based approaches may not be as flashy as a single 'everything' test, but they have a proven impact on public health.