What Is Colorectal Carcinoma? Its Diagnosis And Investigation

Colorectal carcinoma is the cancer of colon (large bowel) as well as rectum. Just like any other cancer, there is uncontrolled cellular growth in the large bowel and rectum. There are many factors that predispose colorectal cancer. Polyps, chronic ulcerative colitis, family history of colorectal carcinoma are the predominant factors. High incidence is observed among people who eat diet consisting high fat and carbohydrate but low in fibers.

Bleeding, fatigue, weakness, severe anemia, constipation alternating with diarrhea is the presenting symptom. The cancer develops slowly and long interval is elapsed before the symptoms appear.

It is therefore necessary to do a screen test if colorectal cancer is suspected. This may include various diagnostic procedures such as examining stool for occult blood, colonoscopy, sonography, etc.

Diagnosis Of Colorectal Carcinoma

Colorectal cancer usually occurs after the age of 50.

Clinching the diagnosis in its early stage is the key for successful treatment of colorectal cancer.

  • Clinical diagnosis can be attained by signs and symptoms and medical history. There is a history of stool mixed with blood. Constipation alternating with diarrhea and severe anemia are other findings. Patient may also have a family history of colorectal cancer.
  • Diagnosis of colorectal carcinoma can be done through physical examination. The doctor may palpate the abdomen to feel a mass or an enlarged organ.
  • In many cases abdominal examination may be negative.
  • Only in case of obstruction he may be able to palpate distended large bowel filled with stools.
  • In late cases the patient may have enlarged liver from metastasis, ascites and secondary deposits in the peritoneum.

Rectal Examination For Colorectal Cancer

  • Digital rectal examination is of great value to detect colorectal carcinoma.
  • During rectal examination, the doctor inserts a lubricated gloved finger into the rectum to feel the mass if present.
  • A mass can be felt with one finger in the rectum and other hand kept on the lower part of the abdomen in men.
  • In case of females, one finger in the rectum and another in the vagina will give a good idea about the degree of infiltration.
  • After rectal examination the doctor may look at the gloved finger for mucus and blood. If it is present, the diagnosis is almost certain for colorectal cancer.

Blood examination and simple stool test may be performed to detect anemia, and blood in the stool. These tests are the most economical for screening of colorectal cancer.

Special Investigations For Colorectal Carcinoma

Proctosigmoidoscopy: It will reveal the growth and may help in taking biopsy. In proctosigmoidoscopy a fiber optic endoscope is introduced through the anus upwards into the sigmoid colon. On the other end of the scope, the doctor is able to visualize the growth through with the lens attached to the scope.

Biopsy: Whenever a growth is detected through proctoscope or sigmoidoscope a biopsy must be taken from the edge of the tumor and also from the central part of the tumor. The biopsy material is then sent for a histological examination. Histological diagnosis is more important as it will suggest the stage of cancer.

Barium enema: It is beneficial when a carcinoma is detected in the lower part of the rectum. When sigmoidoscope fails to visualize the growth because of the spasm of the bowel below it, barium enema X-ray is the only easily available diagnostic tool in the hand of a surgeon.

When carcinoma has been diagnosed by digital examination or by sigmoidoscopy, even then barium examination should be performed to exclude multiple adenomatous polyposis and other carcinomas higher up in the colon.

Endorectal ultrasonography (ERUS): ERUS has revolutionized the management of rectal cancer. The accuracy of digital examination is highly subjective and varies from 60-80%. CT and MRI are not as accurate as this technique in assessing depth of local invasion and involvement of lymph nodes in the rectal area.

Colonoscopy: This is only available in a few specialized units, is definitely the best method to exclude any lesion higher up in the colon.