Cancer of colon and rectum can be clubbed together as colo-rectal cancers as their behaviour is almost same.
Recommendations for colo-rectal cancer screening of The Canadian Task Force on Preventive Health Care (CTFPHC)
Summary of Recommendations for Clinicians and Policy Makers
Screening in Adults Aged 50 to 74
The Task Force recommends screening adults aged 60 to 74 years for colorectal cancer with fecal occult blood testing (FOBT) (either guaiac fecal occult blood testing [gFOBT] or fecal immunochemical testing [FIT]) every two years or flexible sigmoidoscopy (FS) every 10 years. (Strong recommendation; moderate-quality evidence)
The Task Force recommends screening adults aged 50 to 59 years for colorectal cancer with FOBT (gFOBT or FIT) every two years or FS every 10 years. (Weak recommendation; moderate-quality evidence)
Screening in Adults Aged 75 and Older
The Task Force recommends not screening adults aged 75 years and older for colorectal cancer. (Weak recommendation; low-quality evidence)
Screening Using Colonoscopy
The Task Force recommends not using colonoscopy as a primary screening test for colorectal cancer. (Weak recommendation; low-quality evidence)
Grading of Recommendations Assessment, Development and Evaluation (GRADE) Working Group Grades of Evidence
|High quality — Further research is very unlikely to change confidence in the estimate of effect.|
|Moderate quality — Further research is likely to have an important impact on confidence in the estimate of effect and may change the estimate.|
|Low quality — Further research is very likely to have an important impact on confidence in the estimate of effect and is likely to change the estimate.|
|Very low quality — Any estimate of effect is very uncertain.|
The grades of recommendations (strong, weak) and grades of evidence (high, moderate, low, very low) are defined below:
Grading of Recommendations
- Strong recommendations are those for which the Task Force is confident that the desirable effects of an intervention outweigh its undesirable effects (strong recommendation for an intervention) or that the undesirable effects of an intervention outweigh its desirable effects (strong recommendation against an intervention). A strong recommendation implies that most people will be best served by the recommended course of action.
- Weak recommendations are those for which the desirable effects probably outweigh the undesirable effects (weak recommendation for an intervention) or undesirable effects probably outweigh the desirable effects (weak recommendation against an intervention) but appreciable uncertainty exists. Weak recommendations result when the balance between desirable and undesirable effects is small, the quality of evidence is lower, and there is more variability in the values and preferences of patients. A weak recommendation implies that most people would want the recommended course of action, but many would not. Clinicians must recognize that different choices will be appropriate for individual, so they must help each person arrive at a management decision consistent with his or her own values and preferences. Policy-making will require substantial debate and involvement of various stakeholders.
BASIS OF RECOMMENDATIONS
In the judgment of the CTFPHC, gFOBT, FIT and flexible sigmoidoscopy are both reasonable screening tests for patients aged 50-74 years. This recommendation places a relatively higher value on the potential for additional years of life saved in younger patients and a relatively lower value on the lack of statistical significance for mortality benefit in subgroup analyses of younger participants. However, in the judgment of the CTFPHC, the lower absolute benefit expected from screening in people aged 50-59 years warrants a weak recommendation as compared to the strong recommendation for people aged 60-74 years. Making separate recommendations for the two age groups places a relatively higher value on the different balance of benefits to harms by age, and a relatively lower value on the added complexity of having age-group based recommendations.
The recommended age to stop screening is 75 based on reduced life expectancy in older age groups as well as the included ages in the RCTs identified in the systematic review. Although no RCTs have shown improvement in CRC mortality or morbidity for adults over the age of 74, existing trials are underpowered to detect a clinically important difference in this population. However given that incidence rises with age, and that this recommendation is based on low quality evidence, adults over 74 years of age who do not have illnesses which affect their quality of life and/or their lifespan may be less concerned with the lack of trials showing benefit or the potential harms. They should discuss screening with their primary care provider to determine their most appropriate screening option based on their personal values and preferences.
Although colonoscopy may offer clinical benefits that are similar to or greater than those associated with flexible sigmoidoscopy, direct evidence of its efficacy in comparison to the other screening tests (in particular FIT) is lacking. Wait lists for colonoscopy are long in Canada and have increased over the years. Because of higher human resource requirements (requires a specialist such as a gastroenterologist) and greater potential for harms, the ongoing RCTs would have to demonstrate greater efficacy of colonoscopy (in comparison to other tests), before its routine use for screening could be recommended.
This recommendation is weak given the level of uncertainty over the effectiveness and harms of colonoscopy as a screening test. It reflects a relatively higher value on the lack of direct (RCT) evidence of incremental benefit for colonoscopy and on the opportunity costs of using colonoscopy for population screening. The recommendation places a relatively lower value on the indirect evidence suggesting that the clinical benefits of colonoscopy could outweigh its clinical harms. It also places lower value on economic modeling. We note that there are currently four trials underway investigating the mortality benefit of screening colonoscopy. These will be considered as the results become available.