tests are moving into widespread use when a tissue biopsy has insufficient material for DNA testing or when it is not safe to do an invasive biopsy procedure, according to a recent report of results on over 15,000 advanced cancer patients sequenced with the Guardant Health test. A 2014 study of the blood of 846 patients with 15 different types of cancer in 24 institutions was able to detect the presence of cancer DNA in the body. They found tumor DNA in the blood of more than 80 percent of patients with metastatic cancers and about 47 percent of those with localized tumors. The test does not indicate the tumor site(s) or other information about the tumor. The test did not produce false positives. Such tests may also be useful to assess whether malignant cells remain in patients whose tumors have been surgically removed. Up to 30 percent are expected to relapse because some tumor cells remain. Initial studies identified about half the patients who later relapsed, again without false positives. Another potential use is to track the specific DNA mutations driving a tumor. Many new cancer medications block specific molecular processes. Such tests could allow easier targeting of therapy to tumor. Precancerous conditions For easily detected and accessed sites, any suspicious lesions may be assessed. Originally, this was skin or superficial masses. X-ray, then later CT, MRI, and ultrasound along with endoscopy extended the range. Inflammatory conditions A biopsy of the temporal arteries is often performed for suspected vasculitis. In inflammatory bowel disease (Crohn's disease and ulcerative colitis), frequent biopsies are taken to assess the activity of disease and to assess changes that precede malignancy. Biopsy specimens are often taken from part of a lesion when the cause of a disease is uncertain or its extent or exact character is in doubt. Vasculitis, for instance, is usually diagnosed on biopsy. Kidney disease: Biopsy and fluorescence microscopy are key in the diagnosis of alterations of renal function. The immunofluorescence plays vital role in the diagnosis of Crescentic glomerulonephritis. Infectious disease: Lymph node enlargement may be due to a variety of infectious or autoimmune diseases. Metabolic disease: Some conditions affect the whole body, but certain sites are selectively biopsied because they are easily accessed. Amyloidosis is a condition where degraded proteins accumulate in body tissues. In order to make the diagnosis, the gingival. Transplantation: Biopsies of transplanted organs are performed in