The University of California San Francisco Medical Center says rectal cancer occurs when cancerous cells develop in the tissue of the rectum. The Mayo Clinic goes on to say rectal cancer begins as small clumps of cells called adenomatous polyps. Although the vast majority of polyps are benign, some can become cancerous over time.
Although many rectal cancers develop for unclear reasons, certain factors are known to increase the risk. Mayo Clinic says these include age, smoking, inflammatory bowel disease, a high-fat, low-fiber diet, a sedentary lifestyle, and a family or personal history of rectal or colon cancer or polyps.
UCSF Medical Center and cancer.gov both report common symptoms of rectal cancer including a change in bowel habits; diarrhea, constipation, or feeling the bowel does not empty completely; either bright red or very dark blood in the stool; narrower than usual stools; general abdominal discomfort such as frequent gas pains, bloating, fullness or cramps; change in appetite; weight loss with no known reason; constant tiredness and vomiting.
Cancer.gov lists the four types of standard treatment for rectal cancer as surgery, radiation, chemotherapy and targeted treatment.
The types of surgery include polypectomy. If the cancer is found in a polyp, the polyp is often removed during a colonoscopy.
Local excision involves removing the cancer and a small amount of surrounding healthy tissue if the cancer is found on the inside surface of the rectum and hasn’t spread into the rectum wall.
Resection is removing the section of the rectum with cancer and nearby healthy tissue if the cancer has spread into the wall of the rectum.
Cancer.gov says pelvic exenteration is used if the cancer has spread to other organs near the rectum. The lower colon, rectum, and bladder are removed. In women, the cervix, vagina, ovaries, and nearby lymph nodes may be removed. In men, the prostate may be removed.
UCSF Medical Center says some patients who undergo surgery for rectal cancer require a permanent colostomy — a surgically created opening in the abdominal wall through which waste is excreted.