It also helps in determine the size and location of a tumor and whether it has spread to lymph nodes, blood vessels or other structures. This provides information on the cancer's stage, which relates to your prognosis. For example, a growth or mass detected on one of your internal organs can be further evaluated under EUS - without making an incision - to help doctors better understand its nature and prescribe the best treatment option for you. A thin needle - that does not cause pain - can be passed through the endoscope into the tumor to obtain tissue samples. This type of biopsy is called fine-needle aspiration. Cells obtained from the biopsy are examined with a microscope to see if they are cancerous.
Endoscopic ultrasound (EUS) provides a much wider view and includes details not seen with a CT or MRI scan. EUS is also much safer than a CT scan, which uses radiation.