August 2023 | George M. Pikler, M.D., Ph.D., FACP
According to a recent study led by the American Cancer Society, (1) older age and smoking are the most important risk factors associated with a relative and absolute 5-year risk of developing any cancer. For never-smokers (or those who quit a long time ago), BMI and family history of cancer were the most important.
Currently, we have proven screening tests for some types of cancer, including breast, cervical, colorectal, prostate and lung (in high-risk individuals), because they’ve led to finding and treating these types of cancer earlier. Cancers that are found early are often easier to treat and tend to have better outcomes. However, these cancer types represent only approximately one third of all cancer deaths.
For most cancers we do not have proven early detection screening tests. In fact, about 70% of all cancer deaths come from cancers for which there are currently no proven screening tests. These cancers are often diagnosed when signs or symptoms appear at an advanced stage when they can be more difficult to treat.
The development in recent years of multi-cancer early detection tests [MCED] (2) that simultaneously detect and localize a wide range of cancers earlier, hopefully before a person has any symptoms, could reduce the morbidity and mortality associated with cancer. Such tests combine molecular analysis of tumor-related markers present in body fluids, such as circulating cell-free DNA (cfDNA), cell-free RNA (cfRNA), circulating tumor cells (CTCs), with artificial intelligence to simultaneously detect a variety of cancers and further discriminate the underlying cancer type. These tests would complement existing screening approaches to increase the absolute number of cancers detected, including those lacking recommended screening programs.
Ideally, a MCED test should have high sensitivity for early-stage disease detection, high specificity to avoid false-positive results, and the ability to discriminate the tissue of origin (TOO) of the detected cancer. MCED tests, however, still lack validation in prospective multicenter studies to enable their implementation into population-based screening programs and make their way into routine clinical practice.
