Screening and prevention of colorectal cancer
BMJ 2021; 374 doi: https://doi.org/10.1136/bmj.n1855 (Published 15 September 2021) Cite this as: BMJ 2021;374:n1855
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Dear Editor
The state of the art review about “screening and prevention of colorectal cancer” deserves comment.(1)
While screening for colorectal cancer is the most robustly evidence based for efficacy yet, its effectiveness in the real life setting is questionable from a public health perspective: in the US the number of CRC deaths is 1.45/10,000 per year, having decreased very steadily from 2.45 in 1990 (2) well before screening was implemented, not to account the mandatory delay for observing a decrease in mortality. Indeed, two Lancet papers with the fecal tests were published 1996 and screening was not implemented before the mid-2000s.(3)
Why the use of the euphemism ”suboptimal” for the uptake?(1) Screening rates are not only well below the target but also overestimated: uptake for fecal tests only reports one round screening while in pivotal trials mortality was reduced only after 8-13 years of screening in two trials and after 15-18 years in another two. Why deny that the lack of long term compliance precludes efficacy?
Certainly, interventions to increase screening uptake are welcome.(1) However, they must not by-pass the shared decision making process which is already too poorly implemented.(4)
The recent US recommendations to extend screening in individuals between the ages of 45 and 49 should have been critically commented on. Harms from overdiagnosis must not be overlooked: screening deals with healthy people, a risk is not a disease. Why extend screening to lower risk people given the poor uptake in those over 50, even more when being aware that in the US the uptake is 25% in those uninsured who are the most at risk?(5) Why do recommendations, worldwide, endlessly ignore the benefit/harm ratio principle? They fail to take into account sex despite age-specific prevalence for advanced colorectal neoplasms being more than twice as high in men than in women!(6) This risk could have been recalled in the review.
Last, the Journal mentioned that “State of the Art Reviews are commissioned on the basis of their relevance to academics and specialists in the US and internationally”. This could have been an opportunity to highlight that in the US colonoscopy is 8 times more used for screening than fecal tests.(5) In contrast, in England, as in France, the national program only promotes fecal tests. Nevertheless, for a long time, for themselves, gastroenterologists have been relying on colonoscopy.(3)
References
1 Kanth P, Inadomi JM. Screening and prevention of colorectal cancer. BMJ 2021;374:n1855.
2 https://seer.cancer.gov/statfacts/html/colorect.html
3 Braillon A. Colorectal cancer screening: from perspectives to reality. Gastroenterology 2010 ;139:1065
4 Braillon A. Invitation for colorectal cancer screening or forced marketing? Colorectal Dis. 2020;22:465.
5 https://www.cancer.org/content/dam/cancer-org/research/cancer-facts-and-...
6 Brenner H, Altenhofen L, Hoffmeister M. Sex, age, and birth cohort effects in colorectal neoplasms: a cohort analysis. Ann Intern Med 2010;152:697-703.
Competing interests: No competing interests
Re: Screening and prevention of colorectal cancer
Dear Editor
Kanth and Inadomi reported the advantage of screening for the prevention of colorectal cancer (CRC) [1]. In this review, the authors mentioned that the cause of the recent increase in cancer among young adults was unknown, and I present some information.
Cho et al. presented the trend of CRC incidence before and after 50 in subjects aged from 40 to 59 years old [2]. As an example, the average annual percent change (95% confidence interval) of rectal cancer incidence in subjects aged 40-44, 45-49, and 50-54 was 2.1 (1.5-2.7), 1.5 (1.1-1.4), and 1.0 (0.7-1.3), respectively. This means that an increasing trend of CRC incidence was observed under 50 years of age, and CRC incidence was kept after the age of 50, despite CRC screening for this group. Hence, they recommended the initiation of CRC screening earlier than age 50. CRC among young individuals has become a major health issue in developed countries and lowering the age of initial screening is considered to reduce incidence and mortality from CRC. Population-based screening has started at 40 years old in Japan since 1992, although consultation rates in subjects aged from 40 to 69 years were 45% in males and 39% in females.
Ng et al. surveyed the incidence and mortality from CRC in England in the past two decades with special reference to aging [3]. The age-standardized incidence rate of CRC increased by 59% in the 25-49 age groups, and the age-standardized mortality increased by 28.3% in individuals younger than 50 years old. They recommended national screening program extension to under 50 years old, especially targeting recto-sigmoid cancers. Pandey et al. reported the change in the incidence of CRC in populations younger than 50 years in the United States [4]. The incidence of CRC was increasing, and one-third of CRC was rectum and most of the CRC were diagnosed at an advanced stage. They recommended an early screening of CRC in young populations for the purpose of prevention, treatment and reduction of mortality. I think that combination of primary and secondary prevention strategies is required for lowering incidence and mortality of CRC. In addition, cost-benefit analysis should be conducted for the application of screening to younger subjects.
Adenoma can be considered as a precancerous tumor [5], and the increased detection of adenoma will reduce the incidence of CRC. The advantage of CRC screening can be observed in a middle-aged generation, and The US Preventive Services Task Force recommends that screening for CRC in adults aged 45 to 49 years has benefit with moderate certainty [6]. Although ethnic difference in CRC incidence should also be considered [7], low participation rate for CRC screening should be improved by preparing scientific evidence and health education.
References
1. BMJ 2021;374:n1855.
2. Dig Dis Sci. 2021 Sep 5. doi: 10.1007/s10620-021-07213-w
3. Colorectal Dis. 2021 Jul 26. doi: 10.1111/codi.15819
4. Int J Colorectal Dis. 2021;36(7):1515-1524.
5. Cell 1990;61(5):759-767.
6. JAMA 2021;325(19):1965-1977.
7. Clin Gastroenterol Hepatol. 2021 Jul 26. doi: 10.1016/j.cgh.2021.07.035
Competing interests: No competing interests