Which blood test item is a cancer marker?

After a patient is diagnosed with cancer, standard treatment can generally suppress tumor progression. Under normal circumstances, following systemic therapy, physicians assess the effectiveness of treatment through blood tests. Consequently, many cancer patients wish to know which specific blood test parameter serves as a cancer indicator. It is also beneficial for patients to understand these basic concepts, as such knowledge greatly supports their treatment.

Which Blood Test Parameter Serves as a Cancer Indicator?

In clinical practice, alpha-fetoprotein (AFP) is a critically important biomarker used to evaluate tumor status. AFP is an acidic glycoprotein normally present in the fetal liver and yolk sac during early development but rapidly declines after birth. In healthy adults, serum AFP levels are extremely low; however, markedly elevated levels strongly support the diagnosis of primary hepatocellular carcinoma (HCC). Currently, AFP testing is routinely employed for cancer screening, assessment of therapeutic response, and evaluation of surgical resection efficacy—i.e., whether the tumor was completely removed or has recurred.

In addition to AFP, oncologists commonly use carcinoembryonic antigen (CEA) as another key marker for evaluating tumor progression. CEA was first identified in colorectal cancer tissues and fetal intestinal tissue, hence its name. Elevated serum CEA levels occur not only in gastrointestinal cancers but also in malignancies of other organ systems. Serial monitoring of CEA levels aids in assessing treatment response and predicting prognosis: serum CEA typically decreases when the disease improves and rises when it progresses.

What Are the Blood Biomarkers for Cancer Diagnosis?

First, for colorectal cancer, carcinoembryonic antigen (CEA) is a commonly used tumor marker. Significantly elevated CEA levels—e.g., exceeding 100 ng/mL or even 200 ng/mL—raise suspicion for colorectal cancer; however, definitive diagnosis requires colonoscopy with biopsy. Second, for hepatocellular carcinoma, alpha-fetoprotein (AFP) is the principal marker; an AFP level above 400 μg/L, combined with imaging evidence of a hepatic space-occupying lesion, supports the diagnosis of HCC. Third, for pancreatic cancer, carbohydrate antigen 19-9 (CA19-9) may be markedly elevated, though imaging studies remain essential for confirmation.

Definitive pathological diagnosis—obtained via biopsy or surgical specimen—is the gold standard for confirming malignancy. For many other types of cancer, tumor markers lack sufficient specificity; therefore, diagnosis relies on a combination of imaging studies and histopathological examination—not solely on blood biomarker results.

The above provides an overview of which blood test parameters serve as cancer indicators. We hope this information is helpful to you, and wish you good health and happiness.