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Cancer of the Rectum

The rectum is the last part of the large intestine and leads to the anus. Cancer that occurs in the rectum is called rectal cancer. The body’s waste is stored in the rectum until it is eliminated through the anus. Bleeding is the most common symptom of rectal cancer. Other signs and symptoms of rectal cancer may include changes in bowel habits, tenesmus, pencil-shaped stools, constipation, diarrhea and abdominal pain. This cancer can also affect the bladder, local nerves, vagina, prostate and blood vessels in the pelvic cavity of the body, which can cause bladder incontinence or pelvic pain.

Radiation Treatment and Chemotherapy

Radiotherapy is a localized treatment that uses high-energy X-rays or protons to destroy cancer cells. Patients receive a daily prescribed amount of radiation that is directed at the tumor and local lymph nodes. Radiation treatments are given five days a week for several weeks, but the length of time may be shorter, depending on the surgeon’s decision. Radiation treatment side effects are usually specific to the radiotherapy area and diarrhea is the most common side effect. This side effect is temporary and usually goes away after the course of treatment is completed.

Patients with advanced diseases are at a high risk of recurrence and should be treated with chemoradiation either pre-operatively or post-operatively. The primary goal of these two strategies is reducing tumor recurrences in the rectal area. Furthermore, it is usually difficult for a surgeon to leave safe margins around a tumor when dealing with larger tumors, so pre-operative radiotherapy is aimed at downstaging the tumor, which shrinks the tumor, thus making the patient a potential candidate for operation. Compared to pre-operative radiotherapy, studies have shown that chemoradiation with fluorouracil (5-FU) before surgery results in less toxicity and fewer recurrences of the tumor in the rectal area. Many surgeons favor a course of radiation therapy before surgical treatment.

Article author: Dr. Ngan-Ming Tsang