Oncology · Early Detection

A Simple Blood Test Could Detect Multiple Cancers — and Reveal Where They Started

A UCLA-led team describes a blood test that can flag multiple cancers in a single draw and point back to the organ where the tumor began — a move toward inexpensive, scalable cancer screening that no longer needs biopsies for the first clue.

• The test reads molecular signals shed by tumors into the bloodstream and can identify more than one cancer type in a single sample.
• Beyond detection, the assay attempts to pinpoint the tissue of origin — telling a clinician whether the cancer started in the lung, liver, breast or another organ.
• A blood-based approach is far less invasive than biopsy and could be run in routine clinics, opening a path to large-scale population screening at a small fraction of current imaging and procedure costs.

The current way we diagnose cancer still begins with a symptom, an abnormal imaging scan, or a routine screening test aimed at a single organ. Finding the actual tumor usually requires a biopsy — a surgical or endoscopic procedure that takes a piece of tissue and sends it to a pathologist. Biopsies are effective but invasive, expensive, and limited to sites that are physically reachable. A tumor in the pancreas, or a hidden lesion in the lymph nodes, can easily slip past the visible routes medicine has access to.

The emerging alternative is the liquid biopsy — a blood test that looks for traces of cancer that circulate freely in the bloodstream. Tumors shed DNA, RNA, proteins and even whole exfoliated cells into the circulation, and each leaves a chemical signature that, in principle, carries information about the tumor itself.

The UCLA team's work goes one step further. Not only does the test look for the presence of cancer, it attempts to read where the tumor started. That tissue-of-origin information matters because treatment, prognosis and next steps differ sharply between, say, a small lung cancer and an early breast cancer. Today, figuring out the origin of a tumor of unknown primary is one of oncology's hardest problems, and it often requires an extended workup of biopsies and scans.

The practical implications of a multi-cancer, tissue-of-origin blood test are large. A screening protocol that checks for dozens of cancers at once in a single venous draw could be run alongside any routine blood work. Abnormal results would be triaged to targeted imaging and only then, if needed, to biopsy. That order-of-operations change — blood first, tissue second — is exactly what early-detection programs need in order to be affordable and safe enough to scale to whole populations.

The technology is still being validated. The questions that remain are not about principle — whether circulating tumor signals exist, or whether a lab can detect them — but about performance in real-world screening: false positive rates, coverage across cancer types and stages, and behavior in a diverse population that includes smokers, the elderly and people with unrelated inflammatory conditions. If those hurdles are cleared, a single blood draw could eventually sit beside cholesterol and glucose testing as a routine part of preventive medicine.