Rectal cancer is cancer in the rectum, the last part of the
large intestine. It allows waste to pass to the anus and out of
the body. Cancer occurs when cells in the body divide without
control or order. If cells keep dividing, a mass of tissue (a
growth or tumor) forms. The term cancer refers to malignant
tumors. They can invade nearby tissue and spread to other parts
of the body. The doctor will ask about symptoms and medical
history and do a physical exam. Screenings for cancer or
precancerous polyps include: - Digital rectal exam—the doctor's
gloved finger will examine the rectum for lumps or growths -
Fecal occult blood test —a test to check for hidden blood in the
stool —examination of the rectum and colon using a lighted tube
called a colonoscope —examination of the lower colon using a
lighted tube called a sigmoidoscope - Barium enema —rectal
injection of barium coats the lining of the colon and rectum;
done before x-rays to create better images of the lower
intestine - CT colonography —radiology test