Overview
Rectum is the last part of gastrointestinal tract. Rectal cancer and colon cancer are generally clubbed together and discussed as rectum cancer. However, there are many important differences mainly because rectum sits in a narrow cavity called pelvis barely separated from adjacent orangs and bone. It is highly curable if detected early and treated appropriately. It arises from inner lining of the rectum. Most of these start as small mound of flesh called as polyps. Over time some of these polyps develop into colon cancer.
Rectal wall is made of four layers of tissue. Rectal cancer begins in the inner most layer, mucus-producing cells that line the colon. It then advances and spreads.
Risk factors for rectum cancer
Genetic:some gene mutations run in families and increase the risk of rectum cancer. They however, form a small percentage of patients with rectum cancer.
The most common inherited rectum cancer syndromes are:
Symptoms of rectum cancer
These cancers like most other gastrointestinal cancers are asymptomatic in initial stages. The symptoms when occur would include:
Diagnosis
Diagnosis of rectum cancer is established by doing a colonoscopy. It is a procedure in which a flexible thin tube with camera is passed and rectum is seen from inside. If any abnormality is seen then a small sample from it is obtained called as biopsy and examined under microscope confirming the diagnosis.
Determining extent of disease
Depending upon the suspected extent of disease some of the following investigations will be done to determine the exact stage. In addition various lab tests will be done to assess function of various organs. Blood is also tested for CEA (carcinoembryonic antigen), which is produced by most rectum cancers.
Following this work-up a stage will be assigned to the tumor, which spans from I to IV. It is based on three key elements.
The extent (size) of the tumor (T): How far has the cancer grown into the 5 layers of the stomach wall? Has the cancer reached nearby structures or organs?
The spread to nearby lymph nodes (N): Has the cancer spread to nearby lymph nodes? And to how many?
Treatment
Depending upon stage and location of tumor, a treatment plan is made. Surgical resection is the mainstay of treatment. In early tumors surgical resection is first done and then depending upon the final stage in biopsy report, chemotherapy is administered.
To obtain best results for advanced tumors chemotherapy, radiotherapy and surgery are combined in an approach called multimodal treatment. Currently the standard of care is administration of chemotherapy or chemoradiotherapy first called neoadjuvant treatment, followed by surgery.
Chemotherapy is use of special drugs to kill cancer cells. Radiotherapy is use of high-powered X-ray beams to kill cancer cells.
Treatment generally entails a surgical removal of all of the cancer bearing rectum with a margin of healthy tissue, along with adjacent lymph nodes. A key information needed before surgery is how close the tumor is to the anus. The surgical procedure is identified with various names depending on the part of rectum resected; anterior resection, low anterior resection, ultra-low anterior resection or abdominoperineal resection. The remaining parts of intestine are then either reattached or brought out by creating an opening in the wall of abdomen from a portion of the bowel (colostomy) for the elimination of stool into a bag that fits securely over the opening. The decision to reattach or do a colostomy depends upon distance from and involvement of anal canal (anus) by the tumor.
Rectal resection can be done in two ways; open and laparoscopic. In open surgery a single long incision is given over the abdomen and surgery is done. In laparoscopic approach the same surgery can be performed with minimally invasive techniques in which special surgical tools are inserted through small holes. This results in faster recovery and reduced pain compared to the conventional open surgery. This requires special expertise and make sure your surgeon is skilled and has done many of these operations.
Sometimes an operation is done to create an opening in the wall of abdomen from a portion of the bowel (ostomy) for the elimination of stool into a bag that fits securely over the opening. This is done if the tumor is very advanced and causing intestinal obstruction (blockage) and the patient is unfit to undergo major surgery or the cancer has spread to other parts of the body.
In cases where the cancer has spread to the few spots in liver or lung, surgery can be used to remove them. This approach helps the patients live longer and provides them a chance to be free of cancer over the long term.
