Medical
Industrial
Complex
Ineffective Tests!
New Blood Test for Early Detection of Colorectal Cancer Pam Popper, President Wellness Forum Health In July 2024 the FDA approved a blood test called Shield, which is reported to detect colorectal cancers when they are early-stage and curable. Guardant is the manufacturer, and the target market is people aged 45 and older who are at average risk of developing colorectal cancer. The test "works" by detecting fragments of DNA shed from polyps that can turn cancerous. Among the reasons for excitement about this test is that it is more difficult to convince people to agree to colonoscopy or fecal sample testing, and much easier to get them to consent to a blood test. The first problem is the rationale behind development of the test is false. So-called experts continue to state that regular screening can prevent as much as 73% of colorectal cancer deaths. This is not true. The first randomized trial that examined colonoscopy as a means for preventing colorectal cancer, CRC death and all-cause mortality was published in October 2022, long after colonoscopy had become the so-called "gold standard" for early detection of colorectal cancer. The study showed that there was no benefit from colonoscopy when used as a population screening tool.[1] Colonoscopy was not effective for preventing colorectal cancer, death from colorectal cancer, or reducing all-cause mortality. The polyp snipping that often takes place during colonoscopy does not reduce risk. The only strategy that works for lowering the risk of colon cancer is to stop growing polyps. This means that the only justification for enthusiasm for this blood test is that it will be easier to convince people to do it than to convince them to use other screening tools. It might, but the question about this test is the same as for all cancer screening tests: will this reduce the risk of cancer or death from cancer? The answer is a resounding "no." In a study published in March, Guardant reported that Shield detected 87% of cancers that were early stage and curable. The false positive rate was 10%. The false positive rate should not be discounted – the research is clear that it leads to considerable psychological stress, additional expense to confirm results, overtreatment, and being driven further into the medical mill.[2] Much more disturbing is the efficacy rate for detecting large polyps that can become cancerous and kill patients: Guardant only found 13% of these.[3] An FDA advisory committee recommended approval on May 23, but noted that the test’s inability to prevent cancer is a significant limitation. The committee stated that the primary reason that approval was recommended is that the test might prompt people who avoid screening for CRC to do it.[4] On July 29 the FDA approved it. To be clear, the FDA has been approving almost everything submitted for some time now, so FDA approval is not a signal for safety or efficacy. In view of this, it’s important to review a few facts that consumers should know about population colorectal cancer screening programs. At this time, there are no early detection screening tests that reduce the risk of colorectal cancer, or death from colorectal cancer. The primary cause of colorectal cancer is well-known – a diet high in animal foods, refined foods, and fat.[5] [6] [7] [8] Sulfur-containing amino acids are concentrated in animal foods, which irritate the mucosal lining of the colon, leading to polyps.[9] Diets high in fat and protein and containing copious amounts of animal food often cause constipation, a risk factor for colon cancer.[10] This was reported in many studies that looked at the Atkins diet, which was high in animal foods and fat.[11] The beneficial bacteria in your gut thrive on fiber (found only in plant foods),[12] and most people do not eat enough of it. Pathogenic bacteria thrive on protein, fat, and refined sugar.[13] [14] Adopting a high-fiber plant-based (but not necessarily vegan) diet cleans out the colon, nourishes the good critters and stops the irritation and growth of polyps.[15] I’m often asked what people who don’t or won’t eat the right diet should do: would these people benefit from colonoscopy? Or other screening tests? Most of the people who are showing up for colonoscopy today are not eating optimal diets and population screening has not reduced the death rate for any cancer – except for cervical cancer. There is no shortcut for people who will not maintain their bodies properly – or their houses or cars, for that matter. It’s a sad state of affairs, and a commentary on our priorities that many of the people who have let their bodies fall into disrepair take very good care of their houses and cars and would not think of neglecting either. What should you do if you have a family history of CRC, or have already had polyps snipped out due to a previous colonoscopy? First, you can stop growing polyps by changing your diet. If you feel compelled to have some type of screening, the better option is flexible sigmoidoscopy, which was the gold standard before colonoscopy became the standard with no data to justify it. It’s much less invasive and less risky. But I’ll stand by my recommendation to change your diet as the most important strategy for avoiding ALL types of cancer. [1] Bretthauer M, Loberg M, Wieszcry P et al. "Effect of Colonoscopy Screening on Risks of Colorectal Cancer and Related Death." NEJM2022;387:1547-1556 [2] Broderson J, Siersma D. "Long-Term Psychosocial Consequences of False-Positive Screening Mammography." Ann Fam Med 2013 Mar;11(2):106-115 [3] Chung DC, Gray DM, Singh H et al. "A Cell-free DNA Blood-Based Test for Colorectal Cancer Screening." NEJM 2024 Mar;390:973-983 [6] O’Keefe S, Kidd M, Espitalier-Noel G, Owira P. "Rarity of colon cancer in Africans is associated with low animal product consumption, not fiber." Am J Gastroenterol 1999 May;94(5):1373-1380 [7] Giovannucci E. "Modifiable risk factors for colon cancer." Gastroenterol Clin North Am. 2002;31:925–943. [8] Shike M. "Diet and lifestyle in the prevention of colorectal cancer: an overview." Am J Med 1999 Jan 25;106(1A):11S-15S [9] Tuan J, Chen Y. "Dietary and Lifestyle Factors Associated with Colorectal Cancer Risk and Interactions with Microbiota: Fiber, Red or Processed Meat and Alcoholic Drinks." Gastrointest Tumors 2016;3:17-24 [10] Neil Osterwell "Chronic Constipation a Warning Sign for GI Disorders." Medscape Medical News October 26, 2015 [11] Astrup A, Larsen TM, Harper A. "Atkins and other low-carb diets; hoax or effective tool for weight loss?" Lancet 2004 Sep;364(9437):897-899 [12] De Fillipo C, Cavalieri D, Di Paola M et al. "Impact of diet in shaping gut microbiota revealed by a comparative study in children from Europe and rural Africa." PNAS 2010 Aug;107(33):14691-14696 [13] David LA, Maurice CF, Carmody RN et al. "Diet rapidly and reproducibly alters the human gut microbiome." Nature 2014 Jan 23;505(7484):559-63 [14] Turnbaugh PJ, Ridaura VK, Faith JJ, Rey FE, Knight R, Gordon JI. "The effect of diet on the human gut microbiome: a metagenomic analysis in humanized gnotobiotic mice." Sci Transl Med 2009 Nov:1(6):6ra14 [15] David LA, Maurice CF, Carmody RN et al. "Diet rapidly and reproducibly alters the human gut microbiome." Nature 2014 Jan 23;505(7484):559-63 |
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