Avoiding colorectal cancer

Many of us believe that cancer is either going to get us or it won’t. Medical professionals, even, will admit that while modifying lifestyle factors can reduce our risks of getting some  cancers, genetic bad luck is still a primary reason why our population is stricken with cancers that might kill us.

Claiming that we can avoid a certain type of cancer may therefore seem a bit brazen. But in the case of colorectal cancer, a consensus of leading medical experts conclude that because precancerous colorectal cancer polyps can be detected so early  with state-of-the-art screening tests, most of us truly can avoid ever getting colorectal cancer. Or, if we do get this cancer at a very early stage, surgical and other treatments can keep us from succumbing to the disease for many, many years or for our entire lifetimes.

Don’t let commonly quoted statistics deter you from getting screened.

An estimated 101,420 cases of colon cancer and 44,180 cases of rectal cancer will be diagnosed in the U.S. in 2019, and an estimated 51,020 people will die from these two cancers (together known as colorectal cancer) in 2019, according to the American Cancer Society’s 2019 report. That makes colorectal cancer the second leading cause of cancer deaths in the U.S. If you set aside smokers (with their associated high death rate from lung cancer), colorectal cancer is the #1 killer.

So that doesn’t sound very avoidable, does it. Clearly, not all of us will manage to avoid colon cancer and, in fact, many will die from it. However, when you look very closely at all the data, you’ll notice the following:

  • While the 5-year relative survival rate for colorectal cancer is 65% — a not particularly encouraging level, for the 39% of patients diagnosed with “localized disease,” the 5-year survival rate is 90%.

90% … is truly a percentage worth repeating.

Bear in mind that when you look up cancer survival statistics, what’s most often quoted is the “overall” 5-year survival rate for the disease — irrespective of the stage at which the cancer was diagnosed. The “best” cancers to get, by this measure, are breast cancer, prostate cancer, testicular cancer, thyroid cancer, and melanoma. However, this does not mean that individuals with those diseases will all survive five years after  the first five years, or ten years after. They may  live much longer, and in fact often do — but lifetime “cure rates” cannot be concluded from 5-year survival data alone. Survival rates beyond five years are indeed high in the case of most of these “best cancers” — but not, unfortunately, in the case of breast cancer, where there are a significant number of recurrences post-5-years for certain types and advanced stages of the disease.

Caught early, colon cancer can be stopped in its tracks.

The 90% colorectal cancer survival rate for localized disease reflects the fact that — when detected early — colorectal cancer can be prevented or cured — and most often right at the time you undergo the screening procedure, through the detection and removal of precancerous and small cancer growths (known as polyps). If cancer is found during screening, but cannot be removed during that procedure, additional treatment is usually less extensive and more successful if the cancer is diagnosed at an early stage.

The big take-away: Get screened no later than age 50.

The message is simple: Following recommended guidelines for colorectal screening — especially structural exams such as the colonoscopy test — results in a dramatic reduction in premature colorectal cancer death.

Sadly, only about 61 percent (2015 study) of people age 50-74 (who represent the vast majority of colorectal cancer cases) participate in screening. The health care community would like to reach a goal of closer to 80 percent because thousands of lives would be saved as a result.

Screening guidelines are straightforward.

The “gold standard” screening guidelines are those delineated by the U.S. Preventive Services Task Force (USPSTF). In June 2016 (JAMA online), USPSTF updated its guidelines and now recommends “screening for colorectal cancer starting at age 50 years and continuing until age 75 years….”  The report goes on to opine that “the decision to screen for colorectal cancer in adults aged 76 to 85 years should be an individual one, taking into account the patient’s overall health and prior screening history….”

Douglas K. Owens, MD, MS, Henry J. Kaiser, Jr. Professor and director of the Stanford Center for Health Policy and Center for Primary Care and Outcomes Research, was a member of the task force when the guidelines were developed and co-authored the recommendation. In an interview published that year by Stanford News Service, Owens remarked that “evidence convincingly shows screening for colorectal cancer works.…Unfortunately, one-third of people in that [50-75] age group have never been screened, so we are missing an important opportunity to prevent deaths from colorectal cancer.”

More recently, the American Cancer Society updated its own screening guidelines, lowering the recommended age for a person at average risk of colorectal cancer to begin screening from 50 to 45Uri Ladabaum, MD, professor of medicine at Stanford, was the lead author of the study that served as the basis for ACS’s guidelines update. In this March 2019 study, the authors concluded that reducing the starting age for screening to age 45 would reduce the number of deaths from colorectal cancer by over 11,000 over five years, and the number of cancer cases could fall by as many as 29,400. However, that positive outcome would come at a cost to society of an estimated $10.4 billion, as an additional 10.6 million colonoscopies would be required to achieve the better medical outcomes.

Whether the U.S. Preventive Services Task Force will ever follow the ACS recommendation to begin initial screening at age 45 remains to be seen. Even Ladabaum admits, in a Stanford Medicine News Center interview, that “screening older and higher-risk people is higher yield in terms of public health benefit.”  But, interestingly, in the USPSTF 2016 report (written prior to the 2019 Ladabaum study), the authors do note that “modeling suggests there may be some potential advantages to starting colonoscopy screening at an earlier age (45 years) and to extending the interval between screenings with negative findings.”

Is colorectal cancer on the rise in younger populations?

While increased screening in those under 50 may account for a recent increase in the number of diagnosed cases of colorectal cancer in younger populations, some evidence does indicate that a real rise in the incidence of the disease may be occurring at younger ages. In a May 2019 Research Letter (JAMA), authors (lead by Stanford postdoctoral scholar in gastroenterology and hepatology, Reinier Meester, PhD,) state that “evidence suggests that incidence of colorectal cancer (CRC) is increasing among adults younger than 50 years in the United States…. If the increase is the result of earlier detection due to increased use of colonoscopy, earlier stage at diagnosis would be expected, whereas if the increased incidence is the result of true increases in risk, relatively later stage at diagnosis would be expected.” Sure enough, they found that the cancer is currently being discovered at later stages than it was 25 years ago — which indicates that the risk of developing colon cancer at a younger age is  likely increasing.

In a Stanford Medicine SCOPE interview, Meester was asked why colorectal cancer might be increasing in the under-50 age group: “Obesity and an unhealthy diet may play a role, but it’s mostly still unknown.”

The big take-away, re-confirmed:
Don’t wait later than age 50 to get screened.

While the medical community sorts out whether or not age 45 or 50 is the best age for getting an initial screening, weighing considerations of societal cost, the distinct possibility that testing before age 50 will likely show medical benefits when more data is compiled (the Ladabaum study used “modeling” projections, not actual recorded medical results) suggests that — at the very least — one  should not wait a day past age 50 to get one’s first colorectal cancer screening done! Most insurance plans pay for colonoscopies and other screening procedures starting at age 50, although some insurers may pay for procedures starting at age 45, under certain circumstances.

Screening options: The bias in favor of structural (visual) exams

Screening tests can be divided into 2 main groups:

  • Stool-based tests: These tests check the stool (feces) for signs of cancer. These tests are less invasive and easier to have done, but they need to be done more often. Tests include the Fecal Immunochemical test (FIT), the guaiac-based fecal occult blood test (gFOBT) and the stool DNA test.
  • Visual (structural) exams: These tests look at the structure of the colon and rectum for any abnormal areas. This is done either with a scope (a tube-like instrument with a light and tiny video camera on the end) put into the rectum, or with special imaging (x-ray) tests. Tests include the colonoscopy, CT colonography (virtual colonoscopy) and the flexible sigmoidoscopy.

(For further details on screening test options, including risks associated with each test, see this National Cancer Institute guide.)

While some organizations, such as The Centers for Disease Control, do not recommend one screening procedure over another, the bias in favor of structural (visual) exams, such as the colonoscopy, has become much more apparent across a large number of medical organizations in recent years.

The American Cancer Society states: “These tests each have different pros and cons …  and some of them might be better options for you than others. But the most important thing is to get screened, no matter which test you choose.” But the bias of ACS in favor of structural exams, such as the colonoscopy screening procedure, is evident in later statements: “If you choose to be screened with a test other than colonoscopy, any abnormal test result should be followed up with colonoscopy.” This last statement reflects the fact that stool-based tests have both a high percentage of “false positives” (test indicates presence of cancer when there is none) and also a high percentage of “false negatives” (test indicates there is no cancer when actually there is).

Other ways to modify your risk profile

While undergoing timely screening procedures is still the best single plan for reducing your risk of colorectal cancer, lifestyle modifications can and do modify the risks for certain populations.

Your risk of colorectal cancer rises if you are:

  • Obese
  • Physically inactive
  • Smoke cigarettes
  • Consume high quantities of red or processed meat
  • Consume moderate to heavy amounts of alcohol
  • Consume a diet very low in fruits and vegetables and whole-grain fiber

All these risks can be modified by related lifestyle changes.

In addition, some evidence indicates that higher intake of calcium supplements and regular, long-term use of nonsteroidal anti-inflammatory drugs, such as aspirin, reduces the risks of contracting colorectal cancer. A recent study looked at the potential benefits of aspirin, but clearly there are risks associated with long-term aspirin consumption, too — notably, stomach bleeding. As stated by the American Cancer Society, “decision making about aspirin use should include a conversation with your health care provider.”

Genetics and family history: A reason to act

Hereditary and medical factors that increase your risk of colorectal cancer include a personal or family history of colorectal cancer and/or polyps (adenomatous), certain inherited genetic conditions (e.g., Lynch syndrome), a personal history of chronic inflammatory bowel disease (ulcerative colitis or Crohn’s disease), and type 2 diabetes. Unfortunately, these factors are not modifiable in the way that lifestyle factors are. But the fact that genetic conditions and family history cannot easily be altered points up even more strongly the importance of making timely screening procedures your #1 priority.

People at increased risk because of a family history of colorectal cancer or polyps or because they have inflammatory bowel disease or certain inherited conditions may be advised to start screening before age 50 and/or have more frequent screening.

The future: Why wait for it?

Not enough people are being screened for early signs of colorectal cancer, either because they do not know the recommendations or because they are avoiding getting a colonoscopy, which many perceive as an unpleasant procedure.

Researchers at Stanford University are working on the development of a blood test to detect the disease; they hope the test will prove less expensive, less invasive and more convenient than colonoscopies and other currently available screening tests.

While exciting in theory, even lead researcher Shan Wang, PhD, a professor of materials science and engineering and of electrical engineering, stated in a recent interview that “this will be a five- to 10-year study to bring this technology to fruition.” And to truly improve the overall disease detection and subsequent survival rates, the test will have to have high sensitivity and reliability … features that have proved dauntingly difficult to achieve in many other diagnostic testing research development laboratories, across a myriad of disease states.

The take-away here is, once again, the same — and it’s clear and simple: Colorectal cancer is a preventable disease that does not have to remain one of our nation’s leading causes of death. Screening tests, such as the colonoscopy, exist which accurately and reliably detect precancerous polyps or early-stage colorectal cancer. It’s up to each of as individuals to discuss the screening guidelines and options with our physicians, and to follow through with advised appointments.

By Lane McKenna
August 2019