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Current trial data suggest that many MCED tests demonstrate high specificity, often above 99% thereby reducing the likelihood of false positives
Cancer remains one of the leading causes of death globally, with millions of new diagnoses each year. (Image: Getty)
A single blood draw that flags more than 50 cancers before symptoms appear sounds like the next frontier in medicine. Multi-cancer early detection tests are now being discussed in clinics from the US to the UK, with ongoing trials assessing whether they can truly shift cancer care towards earlier diagnosis.
As per ICMR, one in nine Indians now faces a lifetime risk of developing cancer. Since 2022, there has been a projected 12.8% rise of cancer cases in India with 1.57 million new cases in 2025. IARC projections also show, cancer cases climbing to 35 million by 2050, globally.
But the science is more complicated than we know. And before exploring what these new tests can and cannot do, it helps to understand a basic question many patients still ask in clinic- can cancer show up in a single blood test?
News18 spoke to oncology experts who have seen the disease from up-close and understand that cancer diagnosis is not a one-time detection and can be more nuanced than what the science suggests.
Can Routine Blood Work Detect Cancer?
A complete blood count is one of the most commonly ordered tests in medicine. Yet it is not a cancer test. Dr. (Col.) R Ranga Rao, Chairman – Oncology at Paras Health, Gurugram, explains that routine blood investigations are often indirect indicators rather than diagnostic tools.
“A complete blood count does not diagnose cancer,” he says. “But it can sometimes be the first sign that something is not right.” Blood cancers such as leukaemia and lymphoma may present with markedly abnormal white blood cell counts. “We may see very high or very low white cell counts or abnormal patterns, which are classic triggers for further investigation,” Dr Rao notes.
Low haemoglobin levels may suggest anaemia. While common and often unrelated to malignancy, in certain cases it may reflect chronic blood loss from gastrointestinal tumours or conditions such as multiple myeloma. Abnormal platelet counts can also raise suspicion, particularly when the bone marrow is involved.
Still, these findings are clues, not conclusions. “Abnormal results should lead to targeted follow-up tests, imaging, specialised blood studies or a biopsy,” Dr Rao emphasises. “They are warning signals, not a diagnosis.”
Dr Shelly Mahajan, Lab Director at Mahajan Imaging & Labs, reinforces that point. “Many malignancies are silent and do not produce any changes in routine blood parameters,” she says. “Cancer can certainly coexist with completely normal blood reports.” Normal blood work does not rule out cancer, and abnormal blood work does not confirm it.
What Are Multi-Cancer Early Detection Tests?
Multi-cancer early detection tests, often called MCEDs, analyse circulating tumour DNA and other molecular signals shed into the bloodstream. Using genomic sequencing and algorithm-based analysis, they attempt to detect cancer-related patterns before symptoms arise.
Their appeal lies in breadth. Some platforms claim to screen for over 50 cancers, including pancreatic, liver and ovarian cancers, where routine screening options remain limited. Dr Rao describes them as “an exciting development in oncology”, particularly for cancers that are typically diagnosed late.
However, he is clear about their boundaries. “These tests are not diagnostic. A positive result does not mean a person has cancer. Further evaluation with imaging and other investigations is essential. Likewise, a negative result does not completely exclude disease, especially in very early stages.”
How Reliable Are MCED Tests In 2026?
Current trial data suggest that many MCED tests demonstrate high specificity, often above 99 percent. That reduces the likelihood of false positives. Sensitivity, however, varies significantly depending on cancer type and stage.
“Performance differs across platforms and across cancers,” Dr Rao says. “Sensitivity for early-stage disease is not uniform, and that is important when we consider screening value.”
Dr Mahajan points to a fundamental challenge in laboratory medicine: balancing sensitivity and specificity. “Many tumour markers, such as CEA or CA-125, are not cancer-specific,” she explains. “They may be elevated in benign conditions like inflammation or cysts. Elevated values can create anxiety and lead to unnecessary investigations. At the same time, normal values do not always exclude disease.”
Another limitation is biological. Early-stage cancers may be “low-shedding”, meaning they release minimal tumour DNA into the bloodstream. “In such cases,” Dr Mahajan says, “blood tests may appear normal even when a localised and treatable tumour is present.”
What this really means is that a reassuring result may sometimes offer false comfort.
Can One Blood Test Replace Imaging Or A Biopsy?
“A single blood test cannot substitute for the localisation offered by imaging or the cellular confirmation provided by biopsy,” Dr Mahajan states. Imaging modalities such as MRI, CT or PET-CT scans identify and map suspicious lesions. They assess size, spread and anatomical relationships. But even advanced imaging cannot confirm the molecular subtype of a tumour.
“For that, biopsy remains the gold standard,” she says. “Only microscopic tissue examination can definitively determine whether a tumour is benign or malignant.” Blood investigations, including MCED tests, should therefore be seen as supportive components within a broader diagnostic pathway.
Are MCED Tests Ready For Routine Population Screening?
“At this point, MCED tests are not ready for routine population-wide screening,” Dr Rao says. “We still need long-term evidence showing a clear reduction in cancer-related mortality.”
Ongoing studies are evaluating not only detection rates but also outcomes, cost-effectiveness and optimal follow-up strategies. Regulatory bodies have not yet endorsed universal screening.
For now, Dr Rao suggests a selective approach. “They may be considered in high-risk individuals, such as those with strong family histories or known genetic mutations. Even then, they should complement established screening tools like mammography or colonoscopy, not replace them.”
Clear clinical guidelines are still evolving. Questions remain about who should be tested, how positive results should be evaluated and how to minimise overdiagnosis and unnecessary interventions.
What Should People Know About Cancer Testing?
Cancer remains one of the leading causes of death globally, with millions of new diagnoses each year. Earlier detection has long been the central ambition of oncology.
Multi-cancer blood tests represent a bold attempt to rethink screening. Yet, as experts stress, medicine advances step by step.
The responsible path forward lies in evidence, careful clinical judgement and patient-specific risk assessment. For now, established screening programmes, clinical vigilance and informed conversations with oncologists remain the foundation of early detection. One blood test may eventually change cancer care. In 2026, it is a powerful tool in development, not a standalone solution.
February 21, 2026, 12:09 IST
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