Colon Cancer Screening Guidelines - Colonoscopy Better Than Sigmoidoscopy? The Truth and the Myth

Colon cancer screening has a particular personal interest for me.  One of my colleagues in residency training had her father die of colon cancer when she was a teenager.

No one should lose a love one to a disease when caught early is often treatable.  Although for both men and women, colon cancer is the third most common behind lung and prostate cancer in men and behind lung and breast cancer in women, it is the second most lethal.

The problem is that patients are often confused about which test is the right one.  Is it simply a stool test?  Flexible sigmoidoscopy?  Colonoscopy?  Virtual colonoscopy?  Isn't there just a blood test that can be done? (No.)

In real simple terms, this is all you need to know. 

All men and women age 50 and older should be screened for colon cancer.  Even if you feel healthy and well and have no family history, it must be done.  Note that Oprah's doctor, Dr. Oz, arguably a very health conscious individual learned that he had a colon polyp at age 50 after a screening test.  Left undetected, it could have cut his life short.  This wake-up call caused him to abort his original second season premier on weight loss and instead show the country why colon cancer screening matters.  He admitted that if it wasn't for the show and the need to demonstrate the importance of screening to America, he would have delayed having any test done.

The least invasive test is a stool test.  If it is to screen for colon cancer, then the test is done at home and NOT in the doctor's office.  Either the fecal occult blood (FOBT) or the fecal immunochemical test (FIT) are available to screen for unseen microscopic blood that could be a sign of a colon polyp or cancer.  Research shows that when done annually the risk of dying from colon cancer can fall by 15 to 33 percent.  If you don't want any fiber optic cameras in the rectum and lower colon, this is the test for you.  You must do it annually.

The next two tests are similar but often confused - the flexible sigmoidoscopy and the colonoscopy.

The flexible sigmoidoscopy examines the lower third of the colon, known as the sigmoid and the descending colon.  Patients cleanse the lower colon by ingesting a small amount of laxative the day before the procedure.  If a colon growth or polyp is found, it can be biopsied or completely removed during the procedure.  The test is typically done in 15 to 20 minutes.  Patients are awake for the procedure and can go home.  Research shows this test can decrease the number of deaths due to colon cancer.  The risk of the procedure is very small with about 1 in every 5,000 patients having a small tear or perforation.  This flexible sigmoidoscopy test is done every 5 years. 

Like the sigmoidoscopy, the colonoscopy also requires cleansing of colon, however, a gallon of laxative is require to empty the entire colon.  Colon growths and polyps can be removed similarly.  Unlike the sigmoidscopy, however, the colonoscopy requires that patients be sedated.  As a result, you will need someone to take you to the appointment and drive you home.  Although the procedure itself takes about 30 minutes, it can be a few hours from arriving to going home due to the anesthesia.  Out of all of the screening tests, it is the most risky with an estimated perforation rate and cause of serious bleeding affecting in 1 in 1,000 patients.  A colonoscopy is done every 10 years.

Would checking the entire colon with a colonoscopy be better than evaluating the lower third of the colon with a sigmoidoscopy?  Evidence that colonoscopies save lives from colon cancer is lacking.  This subtle but important point is often not mentioned in media reports.  Even the NY Times perpetuated this belief that colonoscopy is the preferred test in its January 20th, 2011 article, "Why People Aren't Screened for Colon Cancer."  When family medicine doctor and lecturer in health care policy at Harvard medical school, Dr. John Abramson, wrote a letter to the NY Times editor in February 15th, 2011, noting the this fact in an unrelated article, the American College of Gastroenterology (ACG) wrote a letter indicating that a colonoscopy is their preferred test for screening.

No wonder patients are confused.

If one dissects the ACG letter carefully, we note the following language (words bolded for emphasis):

American College of Gastroenterology’s 2009 colorectal cancer screening guidelines recommend colonoscopy as the preferred cancer prevention strategy, and guidelines by the American Society for Gastrointestinal Endoscopy in 2006 also endorse colonoscopy because of its ability to view the entire colon and remove potentially precancerous polyps, reflecting a strong opinion of these experts that prevention should be the primary goal of colorectal cancer screening.

While public health experts have recently debated the exact parameters to measure the impact of these screening strategies on mortality, a clinical picture that is muddied by the many variables affecting the quality of the examination, the jury is still out. Indeed colonoscopy’s protective power may lie in a growing appreciation that the biology of precancerous polyps and cancer is different in the right compared to the left colon.

In other words, the recommendation is based on opinion.  There is no language indicating that there is evidence.  The "protective power may lie" in such and such, but hasn't been confirmed.  Examples of when doctors made opinions when evidence was lacking only to change their minds later include hormone replacement after menopause, bone marrow transplant for breast cancer treatment, and prostate cancer screening with PSA.

A study that appeared in the Annals of Internal Medicine in the January 6th, 2009 issue, researchers found that colonoscopies did cut down colon cancer deaths, but it was due to detection of the left sided colon cancers (sigmoid and descending colon) and not to the right side, of which only the colonoscopy can reach.  In other words, a flexible sigmoidoscopy would have detected the cancers as well, which has been observed in previous studies. 

Researchers reviewed health records for persons aged 52 to 90 who received a colorectal cancer diagnosis between 1996 and 2001 and died of colorectal cancer by 2003. These patients were compared to a control group who were selected from the population of Ontario and had not died of colorectal cancer.

According to the researchers, complete colonoscopy was strongly associated with fewer deaths from left-sided colorectal cancer. Conversely, the data showed that colonoscopy seemed to have almost no mortality prevention benefit for right-sided colorectal cancer.

So who do you listen to?  I typically review the guidelines from the American Cancer Society (ACS).  As a group advocating cancer screening and awareness, they should have no bias about what test to use to screen for colon cancer.  For individuals at average risk for colon cancer, ACS notes that to find colon polyps or cancer, either a sigmoidoscopy every 5 years or colonoscopy every 10 years.  Their recommendations don't say the preferred option is a colonoscopy.  The Centers for Disease Control the US Preventive Services Task Force, and the National Cancer Institute also say little about which is preferred. 

What does this mean to you?  For those at average risk and no family history of colon cancer, get screened for colon cancer at age 50.  At the bare minimum, do an annual stool test if you don't want an invasive procedure.  Know that at this time there is no evidence that colonoscopy is better than a flexible sigmoidscopy.

If people tell you otherwise ask them to show you the evidence.
And let me know.

Breast Cancer Screening with Mammograms at age 40? 50? Who is the USPSTF?

When the U.S. Preventive Services Task Force (USPSTF) updated their recommendations and were against routine mammography for women aged 40 to 49, it certainly got a lot of attention. These guidelines are far different than those advocated by the American Cancer Society (ACS) which recommends screening starting at age 40 with annual mammograms.

• Who is the USPSTF?
• What does their recommendations mean for women?
• Why is there conflicting recommendations?

Who is the USPSTF?

The U.S. Preventive Services Task Force (USPSTF) is an independent committee of primary care and preventive physicians that periodically reviews the latest medical research and recommends tests and screening methods that have scientifically been shown to make a difference. As a result, its recommendations are the most conservative of any national organization.

The USPSTF’s recommendations are considered the “gold standard” for determining which clinical services are preventive. They review and look at various screening tests and preventive medications to determine whether there’s proof these interventions work and that the benefits they provide outweigh the potential harm. USPSTF indicates how strongly it recommends a particular method with a letter grade designation (A, B, C, D, and I). An A recommendation means that USPSTF strongly recommends that doctors provide a particular service to eligible patients. A B rating is simply a recommendation. A C means the task force recommends against routinely providing the service, but leaves the decision to the discretion of the individual doctor and patient. A D rating means the group recommends against providing for a particular intervention. An I recommendation indicates that there is not enough evidence to determine whether to recommend for or against a particular procedure.

The USPSTF recommendations tend to be the most conservative of any national organization, because they look for interventions that have proven benefits backed by research. Therefore, promising new technologies and tests that are yet unproven (and at times remain unproven or shown to be no better than existing tests) will not be recommended. As a result, the USPSTF’s guidelines may lag behind those of other organizations. But because they set such a high standard before recommending a particular treatment, insurers should cover the tests and procedures rated A and B.

From the November 2009 update on breast cancer screening update, the USPSTF recommended:

• Against routine screening mammography in women aged 40 to 49 years. The decision to start regular, biennial screening mammography before the age of 50 years should be an individual one and take patient context into account, including the patient's values regarding specific benefits and harms. Grade: C recommendation.
  

• Recommended biennial screening mammography for women aged 50 to 74 years. Grade: B recommendation.
  

• Current evidence is insufficient to assess the additional benefits and harms of screening mammography in women 75 years or older. Grade: I Statement.
  

• Against teaching breast self-examination (BSE). Grade: D recommendation.
  

• Current evidence is insufficient to assess the additional benefits and harms of clinical breast examination (CBE) beyond screening mammography in women 40 years or older. Grade: I Statement.
  

• Insufficient evidence to assess the additional benefits and harms of either digital mammography or magnetic resonance imaging (MRI) instead of film mammography as screening modalities for breast cancer. Grade: I Statement.

What does this mean for women?

First, that there is some evidence that screening between ages 40 to 49 for breast cancer among women with average risk may not be as beneficial as we previously thought. There has been evidence from other countries, like Canada, which have suggested that. However, it is highly unlikely that the American Cancer Society (ACS), being an advocacy group for cancer awareness will change their stance. They said as much with the following:

The USPSTF says that screening 1,339 women in their 50s to save one life makes screening worthwhile in that age group. Yet USPSTF also says screening 1,904 women ages 40 to 49 in order to save one life is not worthwhile. The American Cancer Society feels that in both cases, the lifesaving benefits of screening outweigh any potential harms. Surveys of women show that they are aware of these limitations, and also place high value on detecting breast cancer early.

The American Cancer Society neglects to mention the potential number of extra women harmed with the extra screening between age 40 to 49. An additional 565 women need to be screened above and beyond the 1,339 women to save one life. Within this additional group, many women will have abnormal mammograms and require breast biopsies only to discover that the results were normal. The mammogram was a false-positive.

The USPSTF found in a study in the Annals of Internal Medicine, funded by the National Cancer Institute, that screening every other year achieved over 80 percent of the benefit of screening annually while cutting the false-positive result by nearly half. While every other year screening from age 50 to 69 years resulted in about a median 16.5% (range, 15% to 23%) decrease in breast cancer deaths compared to no screening, starting mammogram at age 40 decrease the death rate further by 3 percent, but increased the costs as more false-positive cases occurred. This article helped influence their recent decision.

Realistically for women, since ACS will not change their recommendation, is that mammograms will still be a covered benefit for any woman who desires to have a mammogram as early as age 40 and can be repeated annually.

What does this mean for you? If you are worried about breast cancer, consider getting screened starting at age 40, however, the benefit of screening may not be as good as we first thought. Certainly if there is a family history of breast cancer, you should discuss with your doctor whether mammography is enough or whether a breast MRI is needed.

Why are there conflicting information?

This won't be the first time USPSTF will have different recommendations than groups like ACS or other professional medical associations. Reasonable doctors and researchers can look at the same data and have different results. It speaks to the problem of screening for cancers and the tools that we currently have. The amount of precision that we would like as patients and doctors in identifying which group of individuals truly need a screening intervention and who does not have yet to be discovered. USPSTF and ACS disagree a bit on colon cancer screening as well. For example, when it comes to colon cancer screening USPSTF gives a grade A recommendation and suggests that:

Using fecal occult blood testing, sigmoidoscopy, or colonoscopy in adults, beginning at age 50 years and continuing until age 75 years. The risks and benefits of these screening methods may vary.

Yet, ACS also recommends virtual colonoscopy or stool DNA testing as reasonable alternatives even though there is no proof they save lives.

Stay tuned. Medical science continues to evolve and recommendations continue to change. The the mean time, exercise regularly, don't smoke, eat five servings of fruits and vegetables daily, and you might extend your life by an additional 14 years!

Your most crucial and trusted relationship is between you and your doctor. Questions? Speak up and ask. Don't be scared. Be informed.

Medicare Won't Cover Virtual Colonoscopy - the Right Decision

In a clear blow to CT device manufacturers like General Electric, the Centers for Medicare and Medicaid Services (CMS) has decided not to cover virtual colonoscopy, which is a non-invasive way of screening for colon cancer.

It's the right decision. Although virtual colonoscopy was recommended by the American Cancer Society (ACS) as a reasonable alternative to the more invasive flexible sigmoidoscopy and colonoscopy, the issue with virtual colonoscopy is radiation exposure when other ways of screening already exist. Certainly from the perspective of ACS, which is an organization focused on increasing cancer screening and awareness, I understand the reason for adding virtual colonoscopy as an option.

But in the reality of the healthcare crisis and the goal of President Obama to make healthcare more affordable for all, decisions like this are inevitable where someone won't be happy with the outcome, in this case CT device manufacturers. With the announcement earlier this week that hospitals, insurers, doctors, device manufacturers will decrease the rate of health care expenses by 1.5% per year over the next decade, tough decisions will be made. Private insurers often follow CMS decisions, so don't expect to have virtual colonoscopy covered by your insurance company to screen for colon cancer.

The funny thing is this decision by CMS will be one of the easier decisions to make because other, although less comfortable procedures exist to screen for colon cancer. (Note that the preparation for all three procedures is the same. One needs to take a laxative to clear the colon of stool so that colon polyps can be visualized).

The other is that CMS will be using guidelines from the US Preventive Services Task Force in basing decisions. USPSTF bases recommendations on scientific evidence and tends to be the most conservative of any organization, like the American Heart Association, American Cancer Society, and various physician organizations.

CMS left the door open for reconsideration of virtual colonoscopy in the future, which is reasonable. Certainly the technology may evolve where radiation exposure is minimal to justify exposing people of average risk to a modality that potentially could increase other forms of cancer.

Review my March entry - Virtual Colonoscopy - Just Say No.

The entire article from the Associated Press follows:

Tue May 12, 10:18 pm ET
WASHINGTON – Medicare won't pay for the so-called virtual colonoscopy procedure, concluding Tuesday that there's inadequate evidence to support the cheaper, less intrusive alternative to the dreaded colonoscopy.
Some experts had hoped that popularizing the X-ray procedure would boost screening for colon cancer, the country's second leading cancer killer. Screening to spot early cancer or precancerous growths has resulted in fewer deaths over the last two decades.
But in a decision posted on its Web site, the Centers for Medicare and Medicaid Services said that the test does not qualify for Medicare coverage. The memo noted that the procedure is performed on people without symptoms and cannot, in itself, rid a patient of precancerous growths, like a regular colonoscopy can.
Medicare does cover regular colonoscopies, in which a long, thin tube equipped with a small video camera is snaked through the large intestine to view the lining. Any growth can be removed during the procedure.
CT colonography, also known as virtual colonoscopy, is a super X-ray of the colon that is quicker, cheaper and easier on the patient, but involves radiation. Both procedures involve preparation to clean out the bowels.
The Medicare memo notes that the virtual colonoscopy has shown better precision in detecting larger polyps than smaller ones.
There's been some division of opinion in the medical community over the virtual colonoscopy. Some doctors question its utility since, if a polyp is found, a regular colonoscopy would typically have to follow, anyway.
Others support it, saying it can result in early cancer detection. The American Cancer Society recommends it as an alternative to a regular colonoscopy.
A concern for Medicare officials, according to their decision Tuesday, was the effectiveness of the procedure for the Medicare population — people 65 and older — as opposed to younger patients. More data is needed to answer that, Medicare said.
The U.S. Preventive Services Task Force opted last fall not to give its stamp of approval to the virtual colonoscopy, citing the risk of radiation among other factors. Medicare said it took that decision into account in reaching Tuesday's determination, which is final.
Some private insurers cover the virtual procedure but others don't. Colonoscopies cost up to $3,000 while the X-ray test costs $300 to $800.

Virtual Colonoscopy? Just Say No

The Center for Medicare and Medicaid Services -- CMS -- is asking for public input on whether virtual colonscopy - CT scanning of the colon -- should be a covered benefit in Medicare to screen for colon cancer.

In early 2008, the American Cancer Society (ACS) added virtual colonoscopy as well as stool DNA testing on its list of suggested screening methods for colon cancer. Screening for colon cancer is recommended for all adults 50 years and older. Besides these two options, the others are:

• fecal stool testing (FIT or FOBT) annually
• double contrast barium enema every 5 years
  
• flexible sigmoidoscopy every 5 years
• colonoscopy every 10 years

While I understand why ACS recommended adding virtual colonoscopy to its list, I don't agree with them. Although it is not as invasive as a sigmoidoscopy or colonscopy since patients lay on the CT scanner table while an x-ray technician works the machines to allow xrays to peer into the body, the colon preparation as well as the insufflation of air to distend the colon, is still required. Also, there is exposure of radiation which increasingly a question doctors are facing. Is doing a scan worth the risk of radiation exposure and potentially higher risk of cancer?

More importantly, if a colon polyp or growth is seen on the virtual colonoscopy, patients still need to have an invasive procedure - sigmoidoscopy / colonoscopy - to do a biopsy or removal of the lesion in question. At least these procedures don't involve any radiation as the instrument is essentially a fiber optic cable.

With the healthcare crisis upon us and the nation asking itself what is affordable and reasonable and what is not, CMS hopefully will not recommend virtual colonoscopy to be added to its list of covered benefits. While the technology is attractive, there are other proven screening tests that albeit uncomfortable are life-saving and don't subject people to unnecessary radiation.

Colonoscopies Miss Colon Cancer

A report in the Journal of the American Medical Association found that flat colon polyps, which are harder to see than raised polyps, were ten times more likely to be cancer. Japanese gastroenterologists found these harder to detect flat polyps by using a dye during colonoscopy. The study also found that having a colonoscopy wasn't enough for adequate screening, but rather how much time and care the doctor took to examine the colon. From the report:

• The growths tend to be smaller when they are cancerous — the size of a nickel instead of a quarter — and are level with the colon wall or depressed like a pothole. They blend in with the surrounding tissue and are difficult to spot.
• While knobby polyps were found in four times as many participants, more than half the colon cancers found — 15 of 28 — were in flat and depressed growths. Thirteen were in polyps.
• Undetected flat growths could explain some mysterious "interval cancers" that show up between screenings in people who have regular colonoscopies, experts said.

Currently the recommended guidelines for colon cancer screening include having a colonoscopy every 10 years starting at the age 50. Recently updated colon cancer screening guidelines from the American Cancer Society now include virtual colonoscopy as well as a stool DNA test. These two newer techniques join screening by using a flexible sigmoidoscopy every 5 years with or without annual stool testing for occult blood or screening via a barium enema. For individuals at average risk (i.e. no family history of colon cancer or no personal history of medical problems like ulcerative colitis that increases an individual's risk of colon cancer greatly), any one of these interventions should begin at age 50.

While I understand the addition of a virtual colonoscopy, which may be more acceptable for the public to accept rather than having a endoscope inserted into the colon for evaluation, I'm not so sure that the radiation exposure related to this screening test is justified. I suspect in the end it was added because:

• The biggest issue is not which screening a patient should get, but that patients come in for screening. All colon cancer deaths can be averted through screening and early treatment, but only 30 percent of people recommended to get screenings actually do, according to the Cancer Society.

• "The challenge we have is getting people to participate in screenings," said Jack Mandel, an Emory University epidemiologist who has studied colon cancer screening tests. "We can prevent these deaths."