Colorectal Cancer

A 75 year old man presented with bleeding PR. A colonoscopy revealed a rectal adenocarcinoma at 10 cms from the dentate line. The following tests will be schedule for him

• Staging CT scan

• MRI pelvis for local staging (nodes and depth of invasion)

• EUS rectum can also be used for local staging and is cheaper than MRI

• CEA

Statement below is related to colorectal cancers?

• Right sided cancers commonly present with iron deficiency anaemia and left sided tumours present with change in bowel habit

• Streptococcus bovis bacteraemia and Clostridium septicum sepsis can be due to underlying colonic malignancies

• Synchronous cancer occur in up to 5 percent of patients

• Serum CEA has prognostic utility in patients with newly diagnosed colorectal cancer

Answer explanation

Synchronous CRCs are defined as two or more distinct primary tumors separated by normal bowel and not due to direct extension or metastasis.

What are risk factors for developing colon cancer?

• Age more than 40 years old

• Genetics FAP & Lynch syndrome

• Inflammatory bowel disease

• High fiber diet

Which of the following is a warning sign of colon cancer?

• Diarrhea or constipation

• Blood in the stool

• Vomiting

• Rectal bleeding

Where does colon cancer usually spread?

• Brain

• Bones

• Kidneys

• Liver

Answer explanation

In primary colon cancer, the cancer is localized to the colon. In advanced stages of colon cancer, the cancer spreads (metastasizes) to distant organs, most commonly the liver, lungs, lymph nodes, and peritoneum.

What foods may cause colon cancer?

• Leafy greens

• Dairy products

• Red meat and processed meat

• Preservative food

The following is associated with the greatest risk for colorectal cancer

• Development of Lynch syndrome

• Hereditary mutation of the APC gene

• Dietary factors

• Lifestyle choices, including alcohol consumption and sedentary habits

Answer explanation

Hereditary mutation of the APC gene is the cause of familial adenomatous polyposis (FAP), in which affected individuals carry an almost 100% risk of developing colon cancer by age 40 years. Hereditary nonpolyposis colon cancer syndrome (HNPCC), or Lynch syndrome, poses about a 40% lifetime risk of developing colorectal cancer.

Which of the following physical findings is suggestive of more advanced disease?

• Fatigue

• Iron-deficiency anemia

• Weight loss

• Ascites

Which of the following is recommended guidelines on colorectal cancer screening?

• Colonoscopy every 10 years, beginning at age 50 years, until the end of life

• Fecal occult blood testing every 5 years after age 50 years

• Sigmoidoscopy every 5 years, with fecal occult blood testing every 3 years

• Annual screening colonoscopy, beginning at age 50 years for high risk individual

Answer explanation

Annual fecal occult blood testing

Sigmoidoscopy every 5 years, along with fecal occult blood testing every 3 years

Screening colonoscopy at intervals of 10 years, from age 50 years to age 75 years (after age 75, screening should be individualized)

Which part of the large bowel do most colorectal cancers occur?

• Ascending colon and rectum

• Transverse colon and rectum

• Descending colon and rectum

• Sigmoid colon and rectum