Fluids can be used for a range of diagnostic tests. For instance, blood tests can reveal tumor markers like PSA (Prostate-Specific Antigen) in prostate cancer or CA-125 in ovarian cancer. Urine tests can detect BTA (Bladder Tumor Antigen) in bladder cancer. Cerebrospinal fluid can be examined for malignant cells in cancers that affect the central nervous system. Fluid samples from pleural effusions or ascites can be analyzed for the presence of cancer cells, helping to diagnose cancers like mesothelioma or ovarian cancer.
