![]() The increased number of patients with the diagnosis of SSA/P is likely due to increased awareness by both endoscopists and pathologists. Advanced lesions occur increasingly and disproportionately among older women. Further, based on mean ages, neoplastic progression from SSA/P to SSA/P-LGD and then to SSA/P-HGD appears to take about 5 years for each step. The inclusion of recently published, more inclusive criteria of patients with SSA/P does not appear to alter the age and sex relationships previously reported. Highly advanced SSA/Ps (SSA/P-HGD and SSA/P-ACA) are also most commonly found in the cecum and ascending colon. In conclusion, SSA/P with and without cytologic dysplasia or carcinoma occurs most commonly in the cecum and ascending colon, and occurs similarly less frequently in the transverse and distal colon. Such confirmation of a different cohort of patients not only confirms the prior data but also indicates that the newer criteria for SSA/P (inclusive of the formerly designated “borderline or indeterminate” serrated polyp) appear to be valid. 12 This study also confirmed, on a 5-fold larger cohort, the key elements of the previous findings from this institution regarding a separate group of SSA/Ps, 12 specifically an approximately 5-year difference between the mean ages for each progressive stage from SSA/P to SSA/P-HGD, as well as the female and right-sided predominance. This cohort, using newer, more inclusive criteria for SSA/P, featured the same demographic and anatomic distribution described previously. As mentioned, this study included a large group of previously designated “borderline or indeterminate” serrated polyps that, according to updated criteria, should be considered true SSA/Ps. We found that right-sided SSA/P and more advanced lesions were concentrated in the cecum and ascending colon, with the distribution in the transverse colon matching the low rate in the distal colon. This study specifically maps the anatomic location of SSA/P with and without cytologic dysplasia or carcinoma (beyond the broad categories “right” and “left” colon), including previously considered “borderline or indeterminate” serrated polyp. 9, 10 In the United States, although the age-adjusted incidence of distal colon cancer has steadily decreased from 1976 to 2005, the incidence of right-sided colon cancers remains unchanged, 11 likely at least in part because of underdetected and/or underdiagnosed sessile serrated adenomas/polyp (SSA/P). 5– 8 Screening colonoscopy with polyp removal is an effective method to reduce the incidence of and mortality from CRC. 4, 5 The remaining 15% to 20% of CRCs are believed to develop through the microsatellite instability pathway, as exemplified by the 3% to 5% of CRC patients with Lynch Syndrome and the 10% to 12% of CRC patients with epigenetic alteration or epigenetic instability due to CpG island methylator phenotype and hypermethylation, both manifested as microsatellite instability pathway cancers. 1– 3 About 80% to 85% of CRCs are thought to arise from preexisting adenomas resulting from the Adenoma Polyposis Coli (APC) gene mutation through the chromosome instability pathway. This book aims to provide scientists and engineers with a conceptual tool, an analytic methodology and the key references for their precision engineering needs.Colorectal cancer (CRC) is the third most common cancer diagnosed in men and women and is the third leading cause of cancer death in the United States. The book also features detailed examples of long stroke flexure mechanisms used in metrology applications, and a detailed example of planar flexure mechanisms having out of plane functionality and used in surgical applications. Topics featured deal with the theoretical foundations for the design of translational and rotational flexures, the simple kinematic analysis of flexure-based mechanisms, and advanced kinematic approaches to the design of complex flexure-based mechanisms using modules in parallel or serial arrangements. This book establishes a conceptual framework for the design of flexure-based articulated structures. Flexure-based mechanisms have gained prominence in a wide variety of fields including robotics, surgical instrumentation, aerospace, astronomy, particle accelerators, metrology and horology. Flexure mechanisms eliminate the disadvantages of classical joints: friction, wear, lubrication and play, while permitting monolithic design. Flexure mechanisms, also known as compliant mechanisms, rely on the elasticity of matter to provide motion to mechanism linkages. Flexure mechanism design is an art, and this book provides the theoretical and practical foundation for scientists and engineers to express their creativity in this field.
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