Colorectal cancer (CRC) is the second most deadly cancer in men and the third most deadly cancer in women, with mortality rates of 3.5% and 3.1%, respectively, and more than 250,000 new CRC cases and 140,000 deaths each year in China, accounting for 20% of new cases and deaths of CRC worldwide in the same period.
The prognosis and regression of CRC are closely related to the stage of the lesion, and the 5-year survival rates of early-stage, locally progressive and late-stage CRC are about 90%, 70% and 12%, respectively. Effective screening, early diagnosis and treatment can significantly reduce mortality. Let’s compare the differences of colorectal cancer screening between Chinese, American and Canadian guidelines.
U.S. ACS Guidelines
Screening for general population: fecal occult blood test (FOBT), fecal histochemical test (FIT), fecal exfoliative DNA screening (sDNA).
Screening for progressive damage: endoscopy, radiological screening such as flexible sigmoidoscopy, colonoscopy, double-contrast barium enema, CT, virtual colonoscopy. All recommended screenings are optional, and prevention of CRC is the first priority for screening.
1. General population CRC screening
From age 50, one of the following five options
1 highly sensitive FOBT or FIT every year, 1 sDNA screening every 3 years; 1 soft sigmoidoscopy every 5 years; 1 double contrast barium enema every 5 years; 1 virtual colonoscopy every 5 years; 1 colonoscopy every 10 years.
2. CRC screening for high-risk groups
Higher-risk groups should have more intense follow-up, including colonoscopy and frequent, earlier initiation of screening.
High-risk groups: include history of adenomatous polyps, history of curative resection of CRC, family history of CRC or colorectal adenocarcinoma in a first-degree relative, persistent inflammatory bowel disease, known or suspected hereditary syndromes such as Lynch syndrome or familial adenomatous polyposis.
Canadian CTFPHC Guidelines
The previous Canadian Task Force on Preventive Health Care (CTFPHC) guidelines (2001) recommended highly sensitive FOBT or FIT every 1 year or every 2 years starting at age 50 for asymptomatic patients and sigmoidoscopy every 5 years.
The recently published new version of the screening guidelines, which combines post-2000 guidelines, systematic reviews, and clinical randomized controlled trials (RCTs) to evaluate the advantages and disadvantages of different screening methods, recommends the following.
Strongly recommended: FOBT or FIT every 2 years or sigmoidoscopy every 10 years at age 60 to 74 years.
Mildly recommended: 1 FOBT or FIT every 2 years or sigmoidoscopy every 10 years for people aged 50-59 years; colorectal cancer screening is not necessary for people aged 75 years or older; colonoscopy is not used as a screening tool.
Description
Analysis of RCTs showed that people aged 60-74 years benefited more from screening than people aged 50-59 years; FIT and FOBT had similar diagnostic specificity, but FIT was more sensitive.
Since most colorectal cancers develop from colonic polyps, this is the theoretical basis for the use of endoscopy to remove polyps or early colorectal cancer foci to reduce colorectal cancer mortality. There is no evidence to support that colonoscopy is more effective than sigmoidoscopy, so colonoscopic screening is not recommended at this time.
China CRC Screening Consensus
Since China has a large population, direct screening by colonoscopy requires a lot of human and financial resources, and colonoscopy has certain risk of complications, so at present, primary screening is performed for the general risk group aged 50 to 75 years, and then fine screening by colonoscopy is performed for the high-risk group.
Colonoscopic biopsy pathological examination is the gold standard for the diagnosis of colorectal cancer.
Initial screening: FOBT, plasma Septin 9 gene methylation monitoring, virtual colonoscopy, colon capsule endoscopy, and sigmoid transcutaneous screening (not valid for proximal CRC development) if available.
High risk group: FOBT positive, previous colorectal adenoma or polyps or precancerous lesions such as UC or Crohn’s.
Family history of Lynch syndrome: MLH1 or MSH2 gene mutation, colonoscopy every 1 to 2 years at age 20-25 years, 1 year after age 35 years; MSH6 or PMS2 gene mutation, colonoscopy every 2 to 3 years at age 25-30 years, 1 to 2 years after age 40-50 years.
APC gene-associated polyposis: sigmoidoscopy or colonoscopy once every 2 years from the age of 10 to 12 years, and once a year after adenoma detection until colon resection.