Tag: Colorectal cancer

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Bowel Cancer

How common is bowel cancer?

Cancer of the large bowel (colon and rectum) is the third common cause of death from cancer. Cancer of the small bowel (duodenum, jejunum and ileum) is quite rare.

In Palliser Health Region (PHR), about 44 new cases of colon and rectal cancers are diagnosed each year. And about 20 patients die from this disease each year.

The incidence of colon and rectal cancer between the ages of 20-49 years is less than 0.18 cases per 1000 population. Between 50-59 years of age, it is less than 0.66 cases per 1000 population. After this the incidence of colon and rectal cancer jumps from 1.74 cases/1000 population at 60 to 3.85 cases/1000 population at age 90.

According to the statistics published by the Alberta Cancer Board, the incidence and death rates for all cancers in PHR are similar to provincial rates. Exception being the female breast cancer incidence rate – it appears to be lower than the provincial rate.

The statistics also show that number of new cases of cancer (all cancers) among males in PHR is consistently higher than females.

What symptoms and signs one should look for?

Rectal bleeding is the most important symptom. It should never be ignored at any age. Most rectal bleeding is due to benign disease. But one can never be sure until the symptom has been investigated and cause of the bleeding is identified.

A person over 60 with rectal bleeding, anemia, weight loss, and mass in the abdomen or rectum probably has colon or rectal cancer – unless it can be proven otherwise.

Other symptoms of significance are: change in bowel habit, change in caliber of stool, and sense of incomplete defecation.

What investigations are required to check for colon and rectal cancer?

A good history and physical examination is very important in all patients. This includes a rectal examination. A blood test may be ordered to check if you are anemic. If there are bowel symptoms without obvious rectal bleeding then stool can be checked for hidden blood (fecal occult blood test – FOBT).

Further investigation depends on your age and risk factors. Patients with low risk factors can be investigated with a flexible sigmoidoscopy (a 60cm flexible instrument). Barium enema may become necessary in some patients. Patients with high risk factors require a colonoscopy (a 160 cm flexible instrument).

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Screening Can Save Your Life

Dear Dr. B: Are there any recommendations for colorectal cancer screening from the Canadian Task Force on Preventive Health Care? Yours, Mr.C.

Dear Mr. C: Yes. A statement from the Task Force on colorectal screening was published recently in the Canadian Medical Association Journal. These recommendations are for asymptomatic people with no personal history of ulcerative colitis, polyps or colorectal cancer. I will summarise the recommendations here:

Recommendations for people over the age of 50 who are at normal risk:

1. There is good evidence to suggest that these people should have annual or biennial (every two years) test to check for non-visible blood in the stool (fecal occult blood tests).

2. There is fair evidence to include flexible sigmoidoscopy (an office procedure). Some recommend this every five years.

3. There is insufficient evidence to recommend whether only one or both (1 and 2) should be performed.

4. There is insufficient evidence to include or exclude colonoscopy as an initial screening test in this age group. Some recommend colonoscopy every 10 years.

Recommendation for people at above-average risk:

1. There is fair evidence to include either genetic testing or flexible sigmoidoscopy of people in families with familial adenomatous polyposis – a condition in which multiple adenomatous polyps progressively develop throughout the colon. The polyps first appear after puberty. Other benign and malignant lesions may appear on the body.

2. There is fair evidence to include colonoscopy screening in the periodic health examination of people in families with hereditary non-polyposis colon cancer – a condition in which three family members are affected with colorectal cancer, two of whom are in successive generations and at least one is under the age of 45 years. It is unclear at what age the screening should start and how often colonoscopy should be done.

3. There is insufficient evidence to recommend colonoscopy for people who have a family history (people who have two or more first degree relatives) of colorectal polyps or cancer but who do not meet the criteria for hereditary non-polyposis colon cancer. Some experts recommend colonoscopy for this group as it is accepted that people with family history of colon and rectal cancer may be at increased risk but that this risk is not well defined.

What are the advantages of screening? To reduce the number of deaths from colorectal cancer.

What are the disadvantages? The incidence of false positive and false negative tests especially with fecal occult blood testing. There is incidence of perforation from flexible sigmoidoscopy (1.4 per 10,000 procedures) and colonoscopy (10 per 10,000 procedures).

Colorectal cancer is the third most common cancer in Canada. It accounts for more than 12 percent of cases of cancer in both sexes.

It was estimated that there would be 17,000 new cases and 6,500 deaths from colorectal cancer in Canada in 2000. These rates, especially among men, are among the highest in the world.

But how many of us are ready to submit ourselves to screening for colorectal cancer? Not many. The embarrassment and discomfort of a rectal examination, unpleasant bowel cleansing before flexible sigmoidoscopy and colonoscopy, risk of bowel perforation, and anxiety dissuade people from coming forward for screening. Even symptomatic patients take a long time before they see their doctors.

Well, Mr. C, if any of the recommendations apply to you then see your doctor and have yourself checked out. Prevention is better than…….?

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Colon Cancer

Dear Dr. B: I have a strong family history of colon cancer. I would like a blood test done every year for early detection of colon cancer. What about CEA blood test that colon cancer patients get so frequently? Why cannot my family doctor order this test for me to make my life easy? Asks Mr. C.

Dear Mr. C: CEA stands for carcinoembryonic antigen. This test has been available for 35 years. It is currently used for patients who have been diagnosed with colon and rectal cancer. Enthusiasm for this test among surgeons and cancer specialists has fluctuated over the years. Originally, the use of this test was poorly controlled. But now the dust has settled and CEA has emerged as the test of choice for patients with colon and rectal cancer.

This test is not good for early detection as there is 30 percent false positive and false negative results in patients who have had no previous colon cancer. Patients with false positive results end up getting many unnecessary investigations. And patients with false negative results may have a false sense of security that they do not have colon or rectal cancer although they may be harbouring one!

CEA is also elevated in other cancers and benign conditions. Therefore, it is hard to be sure if the high level is due to colon and rectal cancer or due to other cancers or benign conditions.

Therefore, the surgeons order CEA after the diagnosis of colon and rectal cancer has been made but before the cancer is resected. CEA provides some idea to the surgeon about prognosis and whether the tumour has already spread. Lower levels indicate limited spread. In about 50 percent of cases, high CEA and increasing CEA after the cancer has been resected, indicates that the cancer has already spread or recurred.

If CEA is high before surgery then it dramatically drops after surgery if the patient has no spread. Then CEA is tested at frequent intervals to see if the level remains the same.

After 33 years of CEA use, the experts have not been able to agree how often CEA should be ordered after successful resection of the cancer. Some do it every month, others every three months for the first two to three years as most recurrences are expected to occur during this critical period. Then the frequency of the blood test is reduced as longer one survives, better the prognosis.
So what is there for early detection of colon and rectal cancer?

Examination of stool for occult blood on regular basis combined with or without endoscopy (flexible sigmoidoscopy or colonoscopy) are currently the best screening tools. Again, each test has its advantages and disadvantages. The optimal method for early detection remains uncertain and people’s compliance rate very poor, as the tests require certain amount of preparation and time. When it comes to colon and rectum, the tests are not very comfortable.

But screening is very important. It has been shown that screening for colon and rectal cancer has reduced mortality by 15 to 33 percent in those who undergo screening routinely. Colon and rectal cancer is the second leading cause of cancer-related deaths in Canada. Therefore, besides screening, early investigation of symptoms like rectal bleeding and change in bowel habit is very important if we want to improve prognosis and survival.

So, Mr. C, discuss with your doctor other methods of early detection as CEA is not a good test for screening for colon and rectal cancer.

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