Colon and rectum are the parts of large intestine. Cancer of the large intestine is a common cancer. Compared to most of the other gastrointestinal cancers, these cancers are less aggressive and if timely treated, have a better outcome. Risk factors for colon cancer can be broadly divided into modifiable and nonmodifiable risk factors. Modifiable risk factors, as the name suggest can be modified by an individual and include smoking, obesity, physical inactivity, high content of red meat and processed meat in the diet. Cooking meat at very high temperatures (frying, broiling, or grilling) creates chemicals that might raise the cancer risk. Nonmodifiable risk factors include increasing age, personal history of colorectal cancer, inflammatory bowel disease (ulcerative colitis, Crohns disease), colorectal adenomatous polyp, and inherited syndromes like familial adenomatous polyposis (FAP), Lynch syndrome (HNPCC) etc.
Symptoms of colorectal carcinoma varies based on the part of the large intestine involved. The patient may develop bleeding per rectum/in the stool, anemia, alteration of bowel habits, increasing constipation, abdominal pain, lump in the abdomen, intestinal obstruction, decreased appetite, weight loss etc. Symptoms in the early stage of the disease are often non-specific and the patient may ignore these. In a suspected patient, the first investigation is usually a colonoscopy with biopsy biopsy. In this investigation, a tube with a camera is inserted via the rectum to visualize the large intestine. After confirmation of the diagnosis, other tests are done which may include- CEA, CT scan of the abdomen , MRI pelvis, PET scan and endorectal ultrasound.
Treatment of colorectal cancer is multimodality and includes surgery, chemotherapy, radiotherapy and immunotherapy. Surgery is the mainstay of treatment and involves removing the part of large intestine involved and adjoining lymph nodes. Rarely patients with rectal cancer present with acute intestinal obstruction and are managed by stenting or surgery. The outcomes are excellent in experienced hands. Following surgery, chemotherapy is given for patients with stage II and III cancer. Follow up includes CEA test every 3 months and yearly colonoscopy and CT scan.