More facts about colon and rectal cancer

The colon and rectum are part of the digestive system. The colon is the first section of large intestine. It continues to absorb nutrients and water from food that has been ingested, as occurs in the small intestine, and serves as a container for waste material. This material progresses to the rectum, the last part of the large intestine, until it is expelled to the outside through the anus.

The colon is divided into several segments: cecum, ascending, transverse, descending and sigmoid. The rectum joins the sigmoid colon.

Both the colon and rectum are made up of several layers of tissue. Depending on whether one or the other layer is affected, this will be the prognosis of cancer.

Cancer that begins in the colon is called colon cancer and cancer that begins in the rectum, rectal cancer.

Depending on whether one part or another is affected, the symptoms will be different and the diagnostic tests will be different and more effective in detecting cancer depending on the area where it appears.

Colon cancer is thought to progress slowly before being diagnosed as such. Before cancer develops, lesions usually appear in the intestine called adenomatous dysplasias or polyps.

Some types of polyps are not cancerous, but having had them increases the likelihood of having cancer in that area of the intestine in the future.

Colon cancer is the second leading cause of cancer death, after lung cancer in men and breast cancer in women. Between 22% and 36% of cases present with advanced disease.

In our country there are 11,000 new cases per year. The mortality induced by this cancer is 10 deaths per 100,000 inhabitants per year, with a tendency to increase.

Colon cancer has been increasing in frequency in developed countries. Together it represents 15% of tumors diagnosed in men.

The five-year survival rate is 90% in those who have had early detection of cancer. But only 37% of these cancers are detected at an early stage.

If the cancer has spread to nearby organs or lymph nodes, the survival rate drops to 65%. And if it has spread to distant organs, the five-year rate is 8%.

Colon and rectal cancer (colorectal cancer) is the second most frequent cancer in the USA and the second leading cause of cancer death, only lung cancer surpasses it in both categories.

In the USA more than 56,000 people die each year due to colon and rectal cancer, higher mortality than prostate cancer in men (31,000) and breast cancer in women (40,800). Most patients with colon cancer have a sporadic onset without a clear etiology. Approximately 20% of patients with colon cancer have a predisposition for the development of this disease.

Familial adenomatous polyposis and hereditary non-polypoid colon cancer (HNPCC, Lynch syndromes) are two predisposing colon cancer syndromes. Patients with HNPCC have an earlier development of carcinoma, with a tendency to develop it in the proximal colon and synchronously and metachronously. Some patients with NCHP syndrome also have cancer of other organs, mainly endometrium. Other conditions that predispose to the appearance of colorectal cancer are, ulcerative colitis, Crohn's disease, cystosomal colitis, exposure to irradiation, and nonfamilial adenomatous polyposis. Symptoms and diagnosis

Studies to detect early stages of colon cancer or premalignant polyps in symptomatic patients include digital rectal examination, fecal occult blood, and colonoscopy.

Symptoms of colon cancer include rectorrhagia, proctorrhagia, and depositional rhythm changes, and depend on the location and extent of the tumor.

Constipation and diarrhea due to narrowing of the intestinal lumen, mixing of blood with fecal matter and mucus, tenesmus (sensation of incomplete bowel movement) are common symptoms present in these patients. Systemic manifestations such as weight loss, asthenia, anorexia, and fatigue from chronic anemia are advanced signs of the disease.

La obstrucción, perforación o hemorragia son complicaciones del cáncer de colon.

Physical examination may reveal the presence of a palpable abdominal or rectal mass. The presence of abdominal distension suggests an advanced degree of rectal or colonic obstruction, ascites may also be found. The entire colon should be examined by colonoscopy and/or an opaque enema prior to surgery in any patient with suspected colon or rectal cancer, unless it cannot be performed due to colony obstruction or any other circumstance. It is preferable to perform colonoscopy because it allows to visualize the lesion, take biopsy of it and detect the presence of synchronous neoplastic polyps and be able to remove them endoscopically if they are not in the colonic sector that is going to be resected.

The presence of metastases can be detected by chest x-ray, plasma CEA level and liver function tests. CEA is not a certain diagnostic test for colorectal cancer in early stages, but it is useful to detect recurrences after curative resections, for this reason it is useful to perform preoperative measurements of CEA. Ultrasound, CT or MRI of the abdomen are used to detect the presence of liver metastases. CT and MRI of the pelvis in patients with rectal cancer is useful to stage the tumor and rule out the presence of disseminations beyond the standard limits of resection, if there are any would be patients candidates for radiant therapy prior to surgery. Endorectal ultrasound is useful only to evaluate local extension, radiotherapy in preoperative form is still under consideration. If the primary lesion in the colon or rectum has features of cancer, preoperative histological confirmation is not necessary. Preoperative histological confirmation is also not routinely required if liver metastases are suspected, because this can be obtained in the same surgery.