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Chapters
Screening Programs | Rationale for CRC Screening
Screening Programs | Rationale for CRC Screening
2012cancercolorectalontarioscreeningUHN
Does Screening Reduce CRC Mortality and Removal of Polyps Study | Rationale for CRC Screening
Does Screening Reduce CRC Mortality and Removal of Polyps Study | Rationale for CRC Screening
2012cancercolonoscopycolorectallongitudinalmayopatientspolyppolypectomypolypsrandomizedreductionUHN
Does Colonoscopy Reduce Mortality of CRC | Rationale for CRC Screening
Does Colonoscopy Reduce Mortality of CRC | Rationale for CRC Screening
2012cancercolonoscopycolorectalincidencemortalityontariopatientsprospectiverandomizedreducesreductionscreeningsidedstudyUHN
Ontario Case Control Study | Rationale for CRC Screening
Ontario Case Control Study | Rationale for CRC Screening
2012colonoscopycolorectalontariopatientsrandomizedreductionscreeningsidedUHN
Transcript

Hi I'm C.S. Ho. I teach at the University Of Toronto. The topic I will discuss today is Rationale for Colorectal Cancer Screening. [BLANK_AUDIO] The main purpose of any cancer screening program is to detect cancer early so that patient will not suffer from it or die from it. At a time of rising health costs all over the world, with the United States taking up 16% of the GDP to fund healthcare, and in Ontario 46%, it will require a strong case to argue for funding

support. What criteria make it a good program, and how does colorectal cancer screening measure against these criterias will be the subject of our discussion. [BLANK_AUDIO] First there should be a significant burden of disease. In this regard,

colorectal cancer ranks the second leading cause of death from cancer in both United States and Canada. It's estimated that 150,000 patients

in the United States will be diagnosed of the disease each year, and 50,000 will die from it. In Canada, it's expected that 1 in 15 individuals will develop colorectal cancer in their lifetime, and 1 in 30 will die from it, and this is a serious health concern. [BLANK_AUDIO] This is graph shows the global distribution of colorectal cancer per 100,000 population.

In Ontario, 7,000 patients is diagnosed to have colorectal cancer, and exceeds all those of the 50 United States. [BLANK_AUDIO] At this point, I would like to make a comment about breast cancer screening versus colorectal cancer screening. In breast cancer

screening, it is the cancer itself that we want to catch early. However in colorectal cancer screening, we want to catch both the pre-clinical Condition and the cancer themselves. Fortunately, the evolution from normal mucosa, to adenoma, to dysplasia, to carcinoma takes 10 to

15 years, and give us ample opportunity to catch this disease. [BLANK_AUDIO] To third criteria for good screening program, is there must be effective

treatment available for the disease. It makes no point to screen for a disease that has no cure or treatment. It only increases the patient's anxiety. In this regard, the five year survival of colorectal

cancer is favorable. Stage 1 and stage 2 disease have a 5 year survival of 93 and 83%. [BLANK_AUDIO] The fourth criteria is that there must be evidence to support that early detection actually improved the outcome, such as mortality

or incidence of colorectal cancer. Does screening colorectal cancer reduce mortality? To answer this question, there were four major

cause effective randomized trials recruiting from 47,000 to 150,000 patients over a long period of 10 to 17 years. And the result is that there is indeed a reduction of mortality anywhere from 12% to 33%. [BLANK_AUDIO] Then the next question comes in. If the

polyps were removed, would they reduce the incidents of colorectal cancer? [BLANK_AUDIO] To answer this question, a longitudinal study was performed, in the 1980s, in the National Polyp Study. In this study, 1418 patients were subjected to polypectomy, and the results of these was compared with three other series taken from historic standard. In the patients who have polypectomy the

occurrence of colorectal cancer is five, whereas in the three other series, one taken from Mayo clinic and the other one from St. Mark, and the third one from the Cancer Registry of United States, shows that there is a reduction of anywhere from 90 to 67% of the incidence of colorectal cancer. So polypectomy does work. The next question then, regards to does colonoscopy on a regular

The study involves screening 700 patients of average risk at the University of Indiana. And they follow this patient up, and compare their results with SEERs, and is found that there is a reduction of 67% in the incidence of colorectal cancer and mortality of 65%. So colonoscopy also

reduces the incidence and also the mortality. However, these are not prospective randomized trials. The final study I want to quote to you is one that is done in Ontario. In Ontario, done at St. Mark's Hospital in Ontario where they look at the registry for patients who are diagnosed and die from colorectal cancer. There are 10,000 patients in this category. These are compared with the

control group who did not die from colorectal cancer, and they are matched according to their sex, age, social status, and location where they live. And they got 31,000 patients. And of these two groups, they found that they have screening colonoscopy 7% in the case presented in the case group. And in the control group, 9.8% had screening colonoscopy. And the result was, there

was significant reduction in mortality in the patient with left sided colorectal cancer. A reduction of 67% whereas, for the right sided colon cancer there was no benefit from screening colonoscopy. Now why is this? So we do not have a good answer, but we can speculate a number of reasons which we won't go into that. So to sum up at this point is that there's no prospective randomized

trial to suggest colonoscopy reduces mortality due to colorectal cancer. But there's plenty ample evidence to suggest that cohort studies suggest that there is a reduction of anywhere from 50 to 67% in mortality. The Ontario study shows that most of the reduction in mortality arise from diagnosing colorectal cancer in the left side with no benefit for colorectal cancer in the right side. And

the reason for that is speculative at this time. Maybe there was missed cancer in this stage. Maybe there was insufficient skill. Maybe the cancer itself are difficult to detect and we just don't know the the answers to that, but overall, there is a reduction, there's a saving, a reduction in mortality. [BLANK_AUDIO]

So the final criteria for screening of colorectal cancer is that

St. Mark's Hospital in Ontario where they look at the registry for patients who are diagnosed and die from colorectal cancer. There are 10,000 patients in this category. These are compared with the

control group who did not die from colorectal cancer, and they are matched according to their sex, age, social status, and location where they live. And they got 31,000 patients. And of these two groups, they found that they have screening colonoscopy 7% in the case presented in the case group. And in the control group, 9.8% had screening colonoscopy. And the result was, there

was significant reduction in mortality in the patient with left sided colorectal cancer. A reduction of 67% whereas, for the right sided colon cancer there was no benefit from screening colonoscopy. Now why is this? So we do not have a good answer, but we can speculate a number of reasons which we won't go into that. So to sum up at this point is that there's no prospective randomized

the cost must be low, and is safe, and accurate. So in this respect, I think, the fecal occult blood testing is a low cost procedure, and it is safe, and it's acceptable. So in summary, there are compelling, evidence-based, level 1 evidence, to support colorectal screening. And you can detect pre-cancerous conditions such as adenomous/g polyp

as well as early cancer leading to improved outcome. And so reduction of mortality. It will benefit the patient, the caregivers, and the society. Thank you. [BLANK_AUDIO]

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