Cancer cells require more blood supply than other kinds of cells because they are growing quickly. In addition, they release factors that encourage the growth of new blood vessels to meet their high needs for energy and oxygen. These new vessels can be very prone to bleeding. In addition, as cancerous polyps grow, they can get large enough to suffer friction and tearing from normal bowel movements. Blood in stool is incredibly common in colon cancer. This may be fresh red blood or older blood that is black and tarry. Either type of blood in stool should be reported to your doctor.Next
