Is the phenotype mixed or mistaken? Hereditary nonpolyposis colorectal cancer and hyperplastic polyposis syndrome

Patterns of polyp histology: predictors of peril in the mucosa

BACKGROUND

Precursor colonic polyps of varied subtypes correlate with the known neoplastic pathways. When patients present with synchronous pre-malignant polyps of multiple histologies, multiple genetic mechanisms are likely to be active, potentially resulting in a more unstable, tumourigenic mucosa.

METHODS

We hypothesized that patients with a combination of sessile serrated adenomas/polyps (SSA/Ps), hyperplastic (HP) polyps and adenomas would be at highest risk of developing dysplasia/cancer compared to SSA/Ps alone, due to the synergistic effect of multiple active carcinogenic pathways. A prospective colonoscopy database was examined for patients with a history of SSA/P. Patients were placed into four groups based on patterns of polyp histology as follows: (i) only SSA/Ps; (ii) SSA/P + HP; (iii) SSA/Ps + adenomas; and (iv) SSA/Ps + HP + adenomas. These groups were compared in terms of the numbers, size, location and histology of polyps and personal or family history of colorectal cancer.

RESULTS

A total of 374 patients were included. The average age was 70 years (range 21-88), and 43% were male. There was a trend towards the most aggressive neoplastic pattern in group 4, associated with a tendency to larger SSA/Ps, more villous architecture in the adenomas and more high-grade dysplasia in both types of polyps. It was also associated with multiplicity of both SSA/Ps and adenomas. No SSA/Ps existing in the absence of adenomas had cytological dysplasia.

CONCLUSION

The combination of SSA/Ps, HP and adenomas in the colorectal epithelium seems to be a marker for aggressive carcinogenesis and suggests that accurate and effective surveillance is important to manage this risk.

Sessile Serrated Polyposis: Not an Inherited Syndrome?

BACKGROUND

Researchers are searching in vain for a coherent genetic explanation for serrated polyposis. We hypothesize that there is no consistent monogenetic inheritance.

OBJECTIVE

The purpose of this study was to describe the serrated polyposis phenotype, assessing features of mendelian inheritance, and to compare these features with patients with a solitary sessile serrated lesion.

DESIGN

This was a retrospective review of a prospectively maintained database comparing patients with serrated polyposis versus solitary sessile serrated lesions.

SETTINGS

The study was conducted at a single-institution tertiary referral center.

PATIENTS

Patients with serrated polyposis meeting World Health Organization criteria type I (≥5 serrated polyps proximal to the sigmoid, ≥2 of which are ≥10 mm in diameter) and isolated sessile serrated lesions were included MAIN OUTCOME MEASURES:: Disease phenotype was the main outcome measured.

RESULTS

A total of 46 serrated polyposis patients were identified. Median age of first sessile serrated lesion was 66 years (interquartile range, 42-70 y). A total of 60.3% were current or past smokers (mean = 38.6 packs per year). Serrated polyposis patients had a higher number of all types of polyps (26.3 vs 4.4) and a higher rate of high-grade dysplasia (19.6% vs 3.7%) compared with patients with a solitary sessile serrated lesion. A total of 36.2% of patients had personal history of noncolorectal cancers, including skin, prostate, breast, thyroid, and renal cell cancers and leukemia. In addition, 32.6% had a family history of colorectal cancer in first- or second-degree relatives; these cancers were not young age of onset. Breast and prostate cancers were also common (family history of any cancer, 83.0%). Ten patients underwent genetic testing: 4 had negative panels, 1 had a pathogenic variant in MSH2, 1 an IVS7 deletion in PTEN, 2 negative APC sequencing (1 negative MYH), and 1 a pathogenic variant in Chek2.

LIMITATIONS

RNF4 was not sequenced. Genetic analysis was performed on a subset of patients.

CONCLUSIONS

The rate of associated cancers suggests an underlying genetic predisposition to disordered growth, but serrated polyposis does not have typical features of dominant inheritance. The association with smoking suggests that familial/environmental factors play a role. See Video Abstract at http://links.lww.com/DCR/B84. POLIPOSIS SERRADA SÉSIL: ¿NO ES UN SÍNDROME HEREDITARIO?: Los investigadores están buscando en vano una explicación genética coherente para la póliposis serrados. Suponemos que no existe una herencia monogenética consistente.1) Describir el fenotipo de póliposis serrada, evaluando las características de la herencia mendeliana, 2) comparar estas características con pacientes con una lesión serrada sésil solitaria.Revisión retrospectiva de una base de datos mantenida prospectivamente que compara pacientes con póliposis serrada versus lesiones serradas sésiles solitarias.Institución única, centro de referencia terciario.Pacientes con póliposis serrada que cumplen con los Criterios de la Organización Mundial de la Salud Tipo I (≥ 5 pólipos serrados proximales al sigmoideo, ≥2 de los cuales tienen ≥10 mm de diámetro) y lesiones serradas sésiles aisladas.Fenotipo de la enfermedad.Se identificaron un total de 46 pacientes con póliposis serrada. La edad mediana de la primera lesión serrada sésil fue de 66 años (RIC: 42-70 años). El 60.3% eran fumadores actuales o pasados (medio 38.6 paquetes / año). Los pacientes con póliposis serrada tuvieron un mayor número de todos los tipos de pólipos (26.3 versus 4.4) y una mayor tasa de displasia de alto grado (19.6% versus 3.7%) en comparación con los pacientes con una lesión serrada sésil solitaria. El 36.2% de los pacientes tenían antecedentes personales de cánceres no colorectales, incluyendo los cánceres de piel, próstata, mama, tiroides, células renales y leucemia. El 32.6% tenía antecedentes familiares de cáncer colorectal en familiares de primer o segundo grado; estos cánceres no eran de inicio de edad temprana. El cáncer de mama y próstata también fue frecuente (antecedentes familiares de cualquier tipo de cáncer: 83.0%). 10 pacientes se sometieron a pruebas genéticas: 4 tenían paneles negativos, 1 tenía una variante patogénica en MSH2, 1 una eliminación IVS7 en PTEN, 2 secuenciación APC negativa (1 MYH negativa) y 1 variante patogénica en Chek2.RNF4 no fue secuenciado. El análisis genético se realizó en un subconjunto de pacientes.La tasa de cánceres asociados sugiere una predisposición genética subyacente al crecimiento desordenado, pero la póliposis serrada no tiene características típicas de herencia dominante. La asociación con el tabaquismo sugiere que los factores familiares / ambientales juegan un papel. Consulte Video Resumen en http://links.lww.com/DCR/B84. (Traducción-Dr. Yesenia Rojas-Khalil).

Hereditary or Not? Understanding Serrated Polyposis Syndrome

PURPOSE OF REVIEW

To present the current understanding of the diagnosis, management, and potential genetic causes of serrated polyposis syndrome.

RECENT FINDINGS

The clinical criteria for serrated polyposis syndrome was recently updated and now includes individuals with five or more serrated polyps proximal to the rectum that are 5 mm in size or greater and at least two that are 10 mm in size of greater as well as individuals with 20 or more serrated polyps throughout the colon with at least five proximal to the rectum. There is a significant risk for colon cancer in first-degree relatives of individuals with serrated polyposis syndrome. However, less than 3% of serrated polyposis syndrome cases are explained by identifiable germline mutations, with mutations in RNF43 being the only currently validated genetic cause. Serrated polyposis syndrome is rarely explained by identifiable germline mutations, but there remains an increased risk for colorectal cancer in first-degree relatives. Referral for genetic counseling and testing is recommended for individuals with serrated polyposis syndrome and a personal history of coexisting adenomatous polyposis or with a concerning family history and can be considered for all individuals with serrated polyposis syndrome. Close endoscopic surveillance of those with serrated polyposis syndrome and their first-degree relatives is recommended. Continued efforts at identifying hereditary causes of serrated polyposis are needed.

Diagnostic Approach to Hereditary Colorectal Cancer Syndromes

Approximately 5 to 10% of colorectal cancers develop within a known hereditary syndrome. Specific underlying genetic mutations drive the clinical phenotype and it is imperative to determine the genetic etiology to provide meaningful surveillance and intervention. Recognizing potential patients and families with a hereditary predisposition is the first step in management. Syndromes can be categorized according to polyp burden as polyposis or nonpolyposis. Clinical assessment should start with a personal and family medical history, physical examination, and evaluation for the presence and type of colorectal polyps or cancers. Key information is gained from these simple steps and should guide the specific genetic analysis for diagnosis. Genetic counseling is a critical component to any hereditary colorectal cancer program and should be conducted before genetic testing to provide education about the implications of test results. This review focuses on the thought process that drives initial clinical evaluation and guides genetic testing for patients with suspected hereditary colorectal cancer syndromes.

Three Colon Adenocarcinomas Arising in a Patient with Serrated Polyposis Syndrome: Case Report and Review of the Literature

Background

Serrated polyposis syndrome (SPS) is a rare entity mainly concerning the 6th decade of life and which is characterized by the presence of multiple large hyperplastic polyps, sessile serrated adenomas, and adenomas within the colon.

Case Report

We describe the case of a SPS patient with 3 synchronous adenocarcinomas. The morphologic features of serrated colorectal lesions, their characteristic molecular alterations, and their role in colorectal cancer development are discussed herein.

Conclusion

Our findings suggest that SPS is a rare condition with an increased risk for colon cancer. Patients suffering from SPS should have regular colonoscopic surveillance, and perhaps those with numerous dysplastic hyperplastic polyps should be treated with colectomy.

Defining the adenoma burden in lynch syndrome

BACKGROUND

Patients with 10 or more lifetime adenomas are candidates for genetic counseling and testing for polyposis syndromes. Lynch syndrome falls under the umbrella of hereditary nonpolyposis colorectal cancer, and it is assumed that patients with Lynch syndrome do not develop multiple adenomas.

OBJECTIVE

The objective of this study was to document the number of adenomas in patients with Lynch syndrome.

DESIGN

This was a retrospective review of clinical, colonoscopy, and pathology records of patients with Lynch syndrome in a prospectively maintained hereditary colorectal cancer database.

SETTINGS

The study was conducted at a single-institution tertiary care center with specialized practice in hereditary colorectal cancer syndromes.

PATIENTS

We included 263 patients with a germline mutation in 1 of the 4 DNA mismatch repair genes.

INTERVENTIONS

Colonoscopy and polypectomy were the study interventions.

MAIN OUTCOME MEASURES

The lifetime cumulative number of colorectal adenomas and their characteristics were measured.

RESULTS

A total of 107 of the 263 patients had 1 or more adenomas. Sixty-one patients had 1 adenoma, 29 (11%) had 2 to 5 adenomas, 6 (2%) had 6 to 9 adenomas, and 11 patients (4%) had 10 or more cumulative adenomas. The maximum number of synchronous adenomas in any individual was 22, and the maximum number of cumulative adenomas in any individual was 24. Twenty-four of the 107 patients with adenomas underwent a total colectomy or proctocolectomy and were excluded from long-term follow-up. In the remaining 83 patients with adenomas, 426 colonoscopies were performed. A total of 220 (54%) were normal or had hyperplastic polyps; 313 adenomas were found in 206 examinations (46%), and 123 (39%) of the adenomas were advanced.

LIMITATIONS

There was variability in the interval of colonoscopy surveillance. Some patients had a variant of unknown significance and were separated from those with a deleterious mutation.

CONCLUSIONS

Although 10 or more adenomas prompt testing for polyposis syndromes, Lynch syndrome should also be considered in the differential diagnosis.

Phenotype characteristics of patients with colonic serrated polyposis syndrome: a study of 23 cases

INTRODUCTION

Serrated polyposis syndrome (SPS) is a rare entity characterized by the presence of multiple hyperplastic polyps in the colon and an increased risk of presentation and development of colorectal cancer (CRC).

OBJECTIVE

To evaluate the clinical and phenotypical characteristics of patients that present one of the 3 WHO criteria for the diagnosis of SPS diagnosed and treated a tour hospital.

PATIENTS AND METHODS

Patients with the diagnosis of SPS during 2005-2012 were revised; 24.208 colonoscopies were performed during this period. Age, sex, family history of CRC (APC/MYH), proximal/mixed/distal phenotype, indication for colonoscopy, number, size, location of the hyperplastic polyps, presence of mixed/adenomatous polyps, CRCI, follow-up and endoscopio/surgical treatment.

RESULTS

A total of 23 cases were included (19 male). The median age was 51. A total of 34% had a prior family history of CRC or polpyps. Distal phenotype was more frequent (48%). Another 73% presented synchronous adenomatous polyps, and 26% a CRC. A total of 57% were asymptomatic. Surgery was performed in 9 cases (6 for cancer and 3 for polyposis), and 14 were treated by polypectomy and observation. Eleven patients (47%) presented recurrent/persistent lesions after initial surgical/endoscopic treatment.

CONCLUSION

SPS is an heterogeneous syndrome that is variable in the type, size, distribution and number of polyps, and is more common in male smokers with a distal phenotype. The majority of patients also present synchronous adenomatous polyps. These patients require an organized multidisciplinary evaluation.

Serrated polyposis: colonic phenotype, extracolonic features, and familial risk in a large cohort

BACKGROUND

Serrated polyposis is a poorly understood and likely underdiagnosed condition. Little is known regarding the colorectal cancer risk, extracolonic phenotype, and cause of serrated polyposis.

OBJECTIVE

The aim of this study is to describe the clinical and family history features of a large cohort of individuals with serrated polyposis.

DESIGN

This is a retrospective cohort study from 2 prospectively collected registries.

PATIENTS

Patients meeting the updated 2010 World Health Organization criteria for serrated polyposis were included.

MAIN OUTCOME MEASURES

We report descriptive statistics for clinical and family history factors.

RESULTS

A total of 52 individuals met criteria for serrated polyposis. Of these, one had Lynch syndrome and was not included in the statistical analyses. Median age at serrated polyposis diagnosis was 51 years (range, 18-77). Twenty-four (47%) patients were male, and 25 (49%) had a history of smoking. Two hundred sixty-eight lower endoscopic procedures were performed; 42 (82%) patients had colorectal adenomas, 8 (16%) had a personal history of colorectal cancer (only 1 was diagnosed during follow-up), 12 (24%) had extracolonic tumors (4 had more than 1 primary tumor), and 19 (37%) reported a family history of colorectal cancer. Esophagogastroduodenoscopy in 30 individuals revealed only 1 (3%) with unexplained gastroduodenal polyps. No association was found between colorectal cancer diagnosis and sex, age at serrated polyposis diagnosis, extracolonic tumor, history of adenoma, or smoking status.

LIMITATIONS

This was a retrospective study with no comparison groups.

CONCLUSIONS

Gastroduodenal polyps are uncommon and likely not associated with serrated polyposis. Although extracolonic tumors were common in our cohort, it is still unclear whether these are associated with serrated polyposis. Our data, along with previous studies, support an association between serrated polyposis and smoking. Further work is still needed to clarify the effect of smoking on polyp development/progression in serrated polyposis.

Serrated pathway: alternative route to colorectal cancer

Serrated polyps have been an area of intense focus for gastroenterologists over the past several years. Contrary to what was thought before, a growing body of literature indicates that these polyps can be precursors of colorectal cancer (CRC). Most of these lesions, particularly those in the proximal colon, have so far been under-recognized and missed during colonoscopy, qualifying these lesions to be the main cause of interval cancers. It is estimated that 10%-20% of CRCs evolve through this alternative, serrated pathway, with a distinct genetic and epigenetic profile. Aberrant DNA methylation plays a central role in the development of this CRC subtype. This characteristic molecular background is reflected in a unique pathological and clinical manifestation different from cancers arising via the traditional pathway. In this review we would like to highlight morphological, molecular and clinical features of this emerging pathway that are essential for gastroenterologists and may influence their everyday practice.

Risk of colonic neoplasia after proctectomy for rectal cancer in hereditary nonpolyposis colorectal cancer

OBJECTIVE

To define the neoplastic risk in the remaining colon after proctectomy for rectal cancer in patients with hereditary nonpolyposis colorectal cancer (HNPCC).

BACKGROUND

The extent of surgery for rectal cancer in HNPCC is controversial. In determining which operation to perform, surgeons and patients must consider cancer risk in the remaining colon as well as functional consequences of removing the entire colorectum. The natural history of colon neoplasia in this situation is understudied and is not well-defined.

METHODS

A single-institution hereditary colorectal cancer database was queried for patients meeting Amsterdam criteria and with rectal cancer. Patient demographics, surgical management, and follow-up were recorded.

RESULTS

Fifty HNPCC patients with a primary diagnosis of rectal cancer treated by proctectcomy were included. Detailed follow-up colonoscopy data were available for 33 patients. Forty-eight high-risk adenomas developed in 13 patients (39.4%). Five patients (15.2%) developed metachronous adenocarcinoma at a median of 6 years (range 3.5-16) after proctectomy, including 3 at advanced stage. One of these patients developed a high-risk adenoma before cancer. Mean interval between the last normal colonoscopy and cancer discovery was 42 months (range 23.8-62.1) with one developing within 2 years. Thus, 17 of 33 patients (51.5%) developed high-risk adenoma or cancer after proctectomy.

CONCLUSIONS

Surgeons and patients need to be aware of substantial risk for metachronous neoplasia after proctectomy. Selection of operation should be individualized, but total proctocolectomy and ileoanal pouch should be strongly considered. If patients undergo proctectomy alone, close surveillance is mandatory.

Serrated polyposis syndrome: Molecular, pathological and clinical aspects

Hyperplastic polyps have traditionally been considered not to have malignant potential. New pathological classification of serrated polyps and recent discoveries about the serrated pathway of carcinogenesis have revolutionized the concepts and revitalized the research in this area. Until recently, it has been thought that most colorectal cancers arise from conventional adenomas via the traditional tumor suppressor pathway initiated by a mutation of the APC gene, but it has been found that this pathway accounts for only approximately 70%-80% of colorectal cancer (CRC) cases. The majority of the remaining colorectal cancer cases follow an alternative pathway leading to CpG island methylator phenotype carcinoma with BRAF mutation and with or without microsatellite instability. The mechanism of carcinomas arising from this alternative pathway seems to begin with an activating mutation of the BRAF oncogene. Serrated polyposis syndrome is a relatively rare condition characterized by multiple and/or large serrated polyps of the colon. Clinical characteristics, etiology and relationship of serrated polyposis syndrome to CRC have not been clarified yet. Patients with this syndrome show a high risk of CRC and both sporadic and hereditary cases have been described. Clinical criteria have been used for diagnosis and frequent colonoscopy surveillance should be performed in order to prevent colorectal cancer. In this review, we try to gather new insights into the molecular pathogenesis of serrated polyps in order to understand their possible clinical implications and to make an approach to the management of this syndrome.

Cancer risks for relatives of patients with serrated polyposis

OBJECTIVES

Serrated polyposis (hyperplastic polyposis) is characterized by multiple polyps with serrated architecture in the colorectum. Although patients with serrated polyposis are known to be at increased risk of colorectal cancer (CRC) and possibly extracolonic cancers, cancer risk for their relatives has not been widely explored. The aim of this study was to estimate the risks of CRC and extracolonic cancers for relatives of patients with serrated polyposis.

METHODS

A cohort of the 1,639 first- and second-degree relatives of 100 index patients with serrated polyposis recruited regardless of a family history of polyps or cancer from genetic clinics in Australia, New Zealand, Canada, and the USA, were retrospectively analyzed to estimate the country-, age-, and sex-specific standardized incidence ratios (SIRs) for relatives compared with the general population.

RESULTS

A total of 102 CRCs were observed in first- and second-relatives (SIR 2.25, 95% confidence interval (CI) 1.75-2.93; P<0.001), with 54 in first-degree relatives (SIR 5.16, 95% CI 3.70-7.30; P<0.001) and 48 in second-degree relatives (SIR 1.38, 95% CI 1.01-1.91; P=0.04). Six pancreatic cancers were observed in first-degree relatives (SIR 3.64, 95% CI 1.70-9.21; P=0.003). There was no statistical evidence of increased risk for cancer of the stomach, brain, breast, or prostate.

CONCLUSIONS

Our finding that relatives of serrated polyposis patients are at significantly increased risk of colorectal and pancreatic cancer adds to the accumulating evidence that serrated polyposis has an inherited component.

Serrated polyposis: an enigmatic model of colorectal cancer predisposition

Serrated polyposis has only recently been accepted as a condition which carries an increased personal and familial risk of colorectal cancer. Described over four decades ago, it remains one of the most underrecognized and poorly understood of all the intestinal polyposes. With a variety of phenotypic presentations, it is likely that serrated polyposis represents a group of diseases rather than a single entity. Further, neoplastic progression in serrated polyposis may be associated with premature aging in the normal mucosa, typified by widespread gene promoter hypermethylation. From this epigenetically altered field, arise diverse polyps and cancers which show a range of molecular features. Despite a high serrated polyp count, only one-third of colorectal cancers demonstrate a BRAF V600E mutation, the molecular hallmark of the canonical serrated pathway, suggesting that though multiple serrated polyps act as a marker of an abnormal mucosa, the majority of CRC in these patients arise within lesions other than BRAF-mutated serrated polyps.

Defining phenotypes and cancer risk in hyperplastic polyposis syndrome

BACKGROUND

Hyperplastic polyposis syndrome is a rare syndrome of colorectal cancer predisposition. Patterns of inheritance of hyperplastic polyposis syndrome are not obvious and the clinical definition is relatively arbitrary. We hypothesize that there are multiple phenotypes included in what is currently called hyperplastic polyposis syndrome. We performed this review of a large series of patients who presented with multiple serrated polyps to look for clinical patterns that may confirm our hypothesis.

METHODS

Hereditary colorectal cancer, colonoscopy, and clinical databases from a single institution were queried for patients meeting the following criteria: 1) ≥ 20 serrated colorectal polyps; 2) ≥ 5 serrated polyps proximal to the sigmoid; 3) ≥ 2 serrated polyps ≥ 10 mm in size; 4) any serrated polyps in a person with at least one first-degree relative who has hyperplastic polyposis syndrome. Records were reviewed for demographics, polyp details, and personal or family history of colorectal extracolonic malignancy.

RESULTS

One-hundred fifteen patients were included. Median age at diagnosis was 62 years and 56% were male. Ninety-seven percent were white. Twenty-five percent of patients had a personal history and 38% had a family history of colorectal cancer. Twenty-eight percent of patients had a personal history and 54% had a family history of extracolonic cancer. Phenotype analysis identified 3 patterns: relatively few large, right-sided polyps (n = 55), many small left-sided polyps (n = 18), and a combination of both left- and right-sided polyps (n = 42). The right-sided phenotype had more sessile serrated polyps and tended to develop colorectal cancer at a younger age.

CONCLUSIONS

There are at least 3 different but overlapping clinical phenotypes within hyperplastic polyposis. Recognizing this clinical heterogeneity is important in defining underlying genetic causes.

Risk of colorectal adenoma and carcinoma after colectomy for colorectal cancer in patients meeting Amsterdam criteria

OBJECTIVE

To report the risk of metachronous colorectal neoplasia after colectomy for cancer in Hereditary Nonpolyposis Colorectal Cancer (HNPCC) syndrome.

SUMMARY BACKGROUND DATA

Patients meeting Amsterdam criteria for diagnosis of HNPCC have a lifetime colorectal cancer risk approaching 80%, and a metachronous cancer rate of approximately 25%. Therefore, when colon cancer is diagnosed, total rather than segmental colectomy is advocated. However, information about adenoma and carcinoma risk after index surgery is still underreported.

METHODS

A hereditary colorectal cancer database was reviewed for patients meeting Amsterdam criteria who underwent colectomy for cancer. Patient demographics, surgical management, and results of follow-up were recorded. Metachronous colorectal adenoma and carcinoma development were the primary end points.

RESULTS

A total of 296 patients (253 with segmental colectomy and 43 with total colectomy/ileorectal anastomosis) were analyzed. Of the 253 segmental colectomy patients, 221 (88%) had postoperative endoscopic surveillance with median follow-up of 104 months. In 74 patients (33%), 256 adenomas were detected, including 140 high-risk adenomas in 48 patients (22%). Fifty-five patients (25%) developed a second colorectal cancer at a median of 69 months after index surgery. Stages of the metachronous cancers were I-16, II-18, III-12, and IV-2. By comparison, 4 of 38 patients (11%) who underwent total colectomy developed subsequent high-risk adenomas and 3 (8%) developed metachronous cancer.

CONCLUSIONS

Amsterdam patients undergoing partial colectomy have a high rate of metachronous high-risk adenomas and carcinomas. Total colectomy for the index cancer is the procedure of choice. For either surgical option, yearly endoscopic surveillance is essential to remove premalignant adenomas.

Risk factors for colorectal cancer in patients with multiple serrated polyps: a cross-sectional case series from genetics clinics

Background

Patients with multiple serrated polyps are at an increased risk for developing colorectal cancer (CRC). Recent reports have linked cigarette smoking with the subset of CRC that develops from serrated polyps. The aim of this work therefore was to investigate the association between smoking and the risk of CRC in high-risk genetics clinic patients presenting with multiple serrated polyps.

Methods and Findings

We identified 151 Caucasian individuals with multiple serrated polyps including at least 5 outside the rectum, and classified patients into non-smokers, current or former smokers at the time of initial diagnosis of polyposis. Cases were individuals with multiple serrated polyps who presented with CRC. Controls were individuals with multiple serrated polyps and no CRC. Multivariate logistic regression was performed to estimate associations between smoking and CRC with adjustment for age at first presentation, sex and co-existing traditional adenomas, a feature that has been consistently linked with CRC risk in patients with multiple serrated polyps. CRC was present in 56 (37%) individuals at presentation. Patients with at least one adenoma were 4 times more likely to present with CRC compared with patients without adenomas (OR = 4.09; 95%CI 1.27 to 13.14; P = 0.02). For females, the odds of CRC decreased by 90% in current smokers as compared to never smokers (OR = 0.10; 95%CI 0.02 to 0.47; P = 0.004) after adjusting for age and adenomas. For males, there was no relationship between current smoking and CRC. There was no statistical evidence of an association between former smoking and CRC for both sexes.

Conclusion

A decreased odds for CRC was identified in females with multiple serrated polyps who currently smoke, independent of age and the presence of a traditional adenoma. Investigations into the biological basis for these observations could lead to non-smoking-related therapies being developed to decrease the risk of CRC and colectomy in these patients.

Lessons from Lynch syndrome: a tumor biology-based approach to familial colorectal cancer

Colorectal cancer (CRC) develops within precursor lesions in the single-celled epithelial lining of the gut. The two most common epithelial lesions are the adenoma and the serrated polyp. CRC is also one of the most familial of the common cancers, and just as there are syndromes associated with increased risk of CRC arising in adenomas, there are also syndromes with increased CRC risk associated with serrated polyps. In this article, we describe the features of such a syndrome, familial serrated neoplasia, which distinguish it from the well-characterized condition Lynch syndrome (or hereditary nonpolyposis CRC), and show that the molecular pathology of tumors forms the basis for this distinction. Lynch syndrome CRC arises almost exclusively within adenomatous precursor lesions, in contrast with familial serrated neoplasia where at least half of the cancers develop in serrated polyps. Finally, rare families exist in which both conditions segregate independently, producing a difficult diagnostic picture.