Why is renal cancer difficult to detect before there are any physical symptoms, i.e., blood in the urine?

Kidney cancer is a type of cancer that does not typically show any physical signs or symptoms until it has grown larger and started to spread. This makes it very difficult for doctors to detect the disease in its early stages, when treatment is more successful.

Renal cancer, specifically, originates in the renal cells that make up the renal system—the kidney itself, as well as its collecting ducts and ureters. Since these cells are deep within the body’s cavities, they aren’t visible on the surface and cannot be felt with our hands during a physical exam. Therefore it takes specialized imaging technology such as an MRI or CT scan to detect abnormalities indicative of tumors.

In addition to this difficulty detecting tumors through imaging scans, many people have no symptoms at all until their tumor has reached an advanced stage; making diagnosis even later than what was initially possible from imaging alone. Blood in urine can sometimes be a sign of renal cancer but usually only occurs after other more common conditions like urinary tract infection or kidney stones have been ruled out first since early cancers don't cause this symptom often enough for physicians to rely heavily on it for detection purposes alone.

For these reasons along with others (such as some genetic factors involved) early detection of renal cancer remains difficult which is why preventative measures are so important such preventive health screens that look into family history and risk factors associated with particular forms of cancer like kidney-related ones.