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Posts Tagged colorectal cancer

When science- and evidence-based guidelines conflict with patient wishes: What’s a doc to do?

Evidence-based medicine triad

There’s a misconception that I frequently hear about evidence-based medicine (EBM), which can equally apply to science-based medicine (SBM). Actually, there are several, but they are related. These misconceptions include the idea that EBM/SBM guidelines are a straightjacket, that they are “cookbook medicine,” and that EBM/SBM should be the be-all and end-all of how to practice clinical medicine. New readers might not be familiar with the difference between EBM and SBM, and here is not the place to explain the difference in detail because this post isn’t primarily about that difference. However, for interested readers, a fuller explanation can be found here, here, here, and here. The CliffsNote version is that EBM fetishizes the randomized clinical trial above all other forms of medical investigation, a system that makes sense if the treatments being tested in RCTs have a reasonably high prior probability of translating to human therapies based on basic science mechanisms, experimental evidence in cell culture, and animal experiments. Using Bayesian considerations, when the prior probability is very low (as is the case for, for example, homeopathy), there will be a lot of false positive trials. Such is how EBM was blindsided by the pseudoscience of “complementary and alternative medicine” (CAM) or, as it is called now, “integrative medicine.”

However, for purposes of this post, SBM and EBM can be considered more or less equivalent, because we are not going to be discussing CAM, but rather widely accepted treatment guidelines based on science, both basic and clinical trial science. I merely mention this difference for completeness and for new readers who might not be familiar with the topics routinely discussed here. For purposes of this post, I’m talking evidence-based guidelines from major medical societies. More specifically, I want to address the disconnect between what patients often want and what our current guidelines state. It’s not just patients either, but doctors; however, for purposes of this post I’m going to focus more on patients. It’s a topic I’ve addressed before, in particular when it comes to breast cancer, where I’ve discussed changes in the mammography screening guidelines and Choosing Wisely guidelines for breast cancer. There are many other examples that I haven’t discussed. (more…)

Posted in: Cancer, Diagnostic tests & procedures

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Diet and exercise versus cancer: A science-based view

Exercise time

One of the most effective spin techniques used by advocates of “integrative medicine” (also sometimes called “complementary and alternative medicine,” or CAM for short) to legitimize quackery has been to claim basically all non-pharmacologic, non-surgical interventions as “integrative,” “complementary,” or “alternative.” Thus, science-based interventions such as diet changes to treat and/or prevent disease, exercise, and other lifestyle alterations are portrayed as somehow so special that they need their own specialty, “integrative medicine,” even though they are simply part of medicine. I pointed this out a mere two weeks ago when I discussed the National Center for Complementary and Integrative Health (NCCIH) review of non-pharmacological treatments for pain. It was a systematic review that was essentially negative but spun as positive for some interventions and lacked some key analyses that a good systematic review includes, such as assessment of the quality of the studies included and evaluating them for bias.

Such were my thoughts over the weekend as I got into a Twitter exchange with an advocate of integrative medicine who was touting the benefits of diet as a cancer preventative and how a course in nutrition “opened her eyes.” That in and of itself wasn’t particularly annoying, although I strongly suspect that the nutrition course she took was not given by actual registered dietitians or other experts in science-based nutrition (she wouldn’t say when questioned). What was annoying is that she trotted out some tropes beloved by integrative medicine proponents, such as the claim that most doctors don’t do prevention because they get paid to treat. She was called out for it:

Oddly enough, on the same day a post from the American Society of Clinical Oncology (ASCO) came up in e-mail lists that discussed the actual evidence for the utility of diet and exercise for cancer prevention. It’s almost as though Twitter were telling me it was time for me to discuss this issue from a science-based perspective. So I will attempt to do so.
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Posted in: Cancer, Epidemiology, Nutrition

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Colonoscopy and Other Colorectal Cancer Screening Options: An Update

When I wrote about colonoscopy in 2010, colonoscopy was thought to be the best screening test for colorectal cancer because it could visualize the entire colon and could remove adenomas that were precursors of cancer. But only fecal occult blood testing (FOBT) and sigmoidoscopy had been proven to decrease colorectal cancer incidence and mortality (by 16% and 28%, respectively). Observational evidence suggested that colonoscopy would reduce the incidence and the number of deaths from colorectal cancer, but there were no randomized controlled trials, and the reduction in incidence of cancer after colonoscopy screening seemed to be restricted to left-sided colon cancers, which didn’t make sense.

We still don’t have any randomized controlled trials of colonoscopy, but a 2013 case-control study from Germany compared patients with and without colorectal cancer and found that those who reported having had a colonoscopy were less likely to develop colon cancer for up to 10 years after the procedure. And now two studies published in the New England Journal of Medicine in September 2013 have shed more light on the subject.
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Posted in: Cancer, Diagnostic tests & procedures

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CAM as a Dumping Ground

I know a woman who is a survivor of colorectal cancer. At one point, doctors had given up hope and put her in hospice, but she failed to die as predicted and was eventually discharged. She continues to suffer intractable symptoms of pain with alternating diarrhea and constipation. I don’t have access to her medical records, but she tells me her doctors have talked about irritable bowel syndrome (IBS) and have also suggested that the heavy doses of radiation used to treat her cancer may have caused permanent damage to her colon. Whatever the cause, her symptoms have seriously interfered with her mobility and her quality of life. Her health care providers have recently recommended questionable treatments in what I think can be construed as using CAM  as a dumping ground for difficult patients.

The Surgeon

Colonoscopy hadn’t shown any obstruction, but one of her doctors had hypothesized that her symptoms might be due to impaired bowel motility in the irradiated area. She was desperate enough to consider surgery if there was a chance that bowel resection or colostomy might improve her symptoms. She belongs to a large, well-known HMO with a good reputation. She asked her primary HMO physician who thought the idea was plausible and referred her to a surgeon. The first surgeon said surgery was not indicated and referred her to another surgeon on staff. In addition to being board certified in general surgery, the second surgeon was allegedly board certified in something related to CAM (my friend can’t remember his exact words and has been unable to verify any such credentials online).

The surgeon recommended acupuncture, not once but twice. My friend’s husband (who teaches statistics at a nearby community college) told the surgeon that he was fascinated by the challenges of double-blinded studies of acupuncture and that he was aware of no benefits beyond the placebo level. The surgeon then retreated a little and suggested that the primary benefit of acupuncture in treating IBS was the “relaxation” effect.

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Posted in: Acupuncture, Herbs & Supplements, Nutrition

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Questioning Colonoscopy

Everybody knows that colonoscopy is the best test to screen for colorectal cancer and that colonoscopies save lives. Everybody may be wrong. Colonoscopy is increasingly viewed as the gold standard for colorectal cancer screening, but its reputation is not based on solid evidence. In reality,  it is not yet known for certain whether colonoscopy can help reduce the number of deaths from colorectal cancer. Screening with fecal occult blood testing (FOBT) and flexible sigmoidoscopy are supported by better evidence, but questions remain.  It seems our zeal for screening tests has outstripped the evidence. 

Statistics show that the life-time risk for an adult American to develop colorectal cancer (CRC) is approximately 6%. Colorectal cancer is the second leading cause of cancer deaths in the United States. In the US there are currently 146,970 new cases   and 50,630 deaths each year. Between 1973 and 1995, mortality from CRC declined by 20.5%, and incidence declined by 7.4% in the United States.  

The US Preventive Services Task Force (USPSTF) recommends screening for colorectal cancer (CRC) using fecal occult blood testing, sigmoidoscopy, or colonoscopy, in adults, beginning at age 50 years and continuing until age 75 years.   (more…)

Posted in: Cancer

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