Rectal Cancer

Rectal cancer refers specifically to cancer of the rectum, the last few inches of the large intestine that is confined in the pelvis. You may have heard it called colorectal cancer because rectal cancer shares the same cause and growth pattern as colon cancer, however rectal cancer treatment is slightly different than colon cancer due to its anatomy. Rectal cancer starts in the inner lining (mucosa) of the rectum as abnormal cells multiply and grow, often in the form of polyps first. The cancer then grow along and through the wall of the rectum and can invade adjacent pelvic organs (bladder, prostate, vagina, sacrum bone) or spread through the lymphatics to other parts of the body. Rectal cancer is curable at early stage, and is preventable with some screening tests.

Symptoms of rectal cancer

Most symptoms of rectal cancer are related to bleeding from the tumor or obstruction of stool passage, and is dependant on the size of the tumor and its location in the rectum. When cancer is early, you may have no symptom. Bleeding from tumor if of small amount may go unnoticed, but may cause anemia over time which is found as an abnormal blood test. As tumor grows bigger, you may notice blood (bright or dark red) mixed in or coating the stool, mucus discharge from rectum, change in bowel pattern (constipation or diarrhea, more narrowed stool, etc), abdominal or pelvic cramps or bloating discomfort, or sensation that you need to defecate often but may not actually have much stool to pass (tenesmus). You may feel more tired than usual due to anemia. Sharper abdominal or pelvic pain occurs when more significant blockage of stool passage results. When the tumor grows through the rectal wall to invade adjacent organs, you may experience recurrent urine infection, stool or bloody discharge from vagina or with urination. Tumor extending down to the anal canal into the anal sphincter (muscle that you use to control your bowel) may additionally cause some degree of stool incontinence. In more advanced stage cancer, you may have weight loss, nausea, decreased appetite, generalized weakness.

Diagnosis of rectal cancer

A thorough history and physical exam, blood test, and colonoscopy with biopsy are needed for diagnosis. Dr. Choi will perform a digital rectal exam (palpation of the rectal wall and anal canal with a gloved lubricated finger) and proctoscopy (direct viewing with a long narrow lighted instrument call proctoscope) in the office, which are important to determine the location of the tumor and its relation to the anal sphincter. When biopsy confirms rectal cancer, imaging tests (typically CT scan and MRI) are used to determine the cancer stage clinically.

Treatment of rectal cancer

Treatment of rectal cancer is individualized based on the clinical cancer stage, the proximity of the tumor to the anal sphincter, and patient's baseline anal/bowel function, and involves a multidisciplinary team (including the colorectal surgeon, medical and radiation oncologist, pathologist, other supporting staff). Treatment typically involves surgery to remove the sigmoid colon and rectum, along with the surrounding lymph nodes. If the cancer has invaded into the muscle layer of the rectal wall or had spread to adjacent lymph nodes, chemo and radiation therapy is offered first before surgery. If the tumor is very close to the anal sphincter, chemo and/or radiation may be used in an attempt to shrink the tumor away from anal sphincter so it can be safely removed without harming the sphincter muscle. In select case where the tumor is small and involves the mucosa only, local excision to remove the tumor with a rim of normal tissue may be an option. Dr. Choi typically performs rectal resection surgery with laparoscopic (minimally invasive) technique. A temporary ileostomy may be created (the bowel is brought out to the skin and the fecal waste is eliminated into a bag attached to the skin) if there is high risk of problem/delay healing of the reconnected bowel (the anastomosis), such as pre-surgery radiation treatment and a very low anastomosis close to the anus. In rare cases where the anal sphincter is involved by the cancer and cannot be "saved", the anus will need to be removed and patient will have a permanant colostomy. The removed rectum is examined under the microscope to determine the pathological (true) stage, and determination of whether additional chemotherapy is needed after surgery is then made. If cancer has already spread remotely to other organs upon initial diagnosis (stage IV/ metastasized, commonly to liver or lung), upfront chemotherapy is typically offered. After adequate treatment of the cancer, you will need check up along with blood tests and imaging studies at regular intervals to monitor for cancer recurrence.

Prevention of rectal cancer

Often it is not possible to pinpoint the exact cause of rectal cancer. However there are few known risk factors for rectal cancer, some of these preventable. Since most rectal cancer starts as polyps and most cancer are diagnosed after age 50, getting your first screening colonoscopy at age 45 (the current recommended age) can allow polyp detection and removal before polyp turns into cancer. You may need to have screening colonoscopy at earlier age and at more frequent interval if you are at higher risk of rectal cancer, such as family history of colorectal cancer (especially in parents or siblings), multiple cancers in the family, certain genetic syndrome such as Lynch syndrome and Familial Adenomatous Polyposis (FAP), personal history of colorectal polyps, inflammatory bowel disese or other cancer such as breast, uterine or ovarian cancer. Eating a diet high in fiber and low in fat, regular exercise, avoiding cigarette smoking and minimizing alcohol consumption may also be protective.