Colonoscopic screening of persons with suspected risk factors for colon cancer. I. Family history

Screening or Symptoms? How Do We Detect Colorectal Cancer in an Equal Access Health Care System?

BACKGROUND

Detection of colorectal cancer ideally occurs at an early stage through proper screening. We sought to establish methods by which colorectal cancers are diagnosed within an equal access military health care population and evaluate the correlation between TNM stage at colorectal cancer diagnosis and diagnostic modality (i.e., symptomatic detection vs screen detection).

MATERIALS AND METHODS

A retrospective chart review of all newly diagnosed colorectal cancer patients from January 2007 to August 2014 was conducted at the authors' equal access military institution. We evaluated TNM stage relative to diagnosis by screen detection (fecal occult blood test, flexible sigmoidoscopy, CT colonography, colonoscopy) or symptomatic evaluation (diagnostic colonoscopy or surgery).

RESULTS

Of 197 colorectal cancers diagnosed (59 % male; mean age 62 years), 50 (25 %) had stage I, 47 (24 %) had stage II, 70 (36 %) had stage III, and 30 (15 %) had stage IV disease. Twenty-five percent of colorectal cancers were detected via screen detection (3 % by fecal occult blood testing (FOBT), 0.5 % by screening CT colonography, 17 % by screening colonoscopy, and 5 % by surveillance colonoscopy). One hundred forty-eight (75 %) were diagnosed after onset of signs or symptoms. The preponderance of these was advanced-stage disease (stages III-IV), although >50 % of stage I-II disease also had signs or symptoms at diagnosis. The most common symptoms were rectal bleeding (45 %), abdominal pain (35 %), and change in stool caliber (27 %). The most common overall sign was anemia (60 %). Screening FOBT (odds ratio (OR) 8.7, 95 % confidence interval (CI) 1.0-78.3; P = 0.05) independently predicted early diagnosis with stage I-II disease. Patient gender and ethnicity were not associated with cancer stage at diagnosis.

CONCLUSIONS

Despite equal access to colorectal cancer screening, diagnosis after development of symptomatic cancer remains more common. Fecal occult blood screen detection is associated with early stage at colorectal cancer diagnosis and is the focus for future initiatives.

Impact of a family history of colorectal cancer on the prevalence of advanced neoplasia at colonoscopy in 4,967 asymptomatic patients

BACKGROUND AND AIMS

A family history of colorectal cancer is considered an independent risk factor for advanced neoplasia at colonoscopy. The expected outcome for screening colonoscopy in patients with a family history is not well established in all populations.

METHODS

We designed a large, prospective study of an unselected population in San Diego, California to assess the impact of a family history of colorectal cancer on the prevalence of advanced neoplasia on screening colonoscopy.

RESULTS

We evaluated 6,905 consecutive patients referred for colonoscopy between January 2005 and December 2006. Of the 4,967 who met the inclusion criteria, the mean age was 58.8 and consisted of 58.6% women. Overall 930 (18.7%) had neoplasia and 249 (5%) had advanced neoplasia, eight (0.16%) of which were cancer. The 4,967 patients were divided into 643 with and 4,324 without a family history of colorectal cancer. Of the 643 patients with a family history, 38 (5.9%) had advanced neoplasia, one of which was cancer. Of the 4,324 patients without a family history, 211 (4.9%) had advanced neoplasia including seven cancers. The relative risk for finding advanced neoplasia in patients with a single affected first degree relative was 1.21 (95% CI, 0.87-1.69; P = 0.31).

CONCLUSIONS

A family history of one first-degree relative with colorectal cancer did not predict a significantly higher prevalence of advanced neoplasia at screening colonoscopy in this Southwestern cohort.

Increased risk of adenomas in individuals with a family history of colorectal cancer: results of a meta-analysis

OBJECTIVE

It is unclear to what extent the increased risk of colorectal cancer in individuals with a family history of colorectal cancer and no known genetic disorders is associated with a higher adenoma prevalence. Our aim is to estimate the relative difference in adenoma prevalence and its age-pattern in individuals with a family history of colorectal cancer compared to those without.

METHODS

We performed a literature search to identify colonoscopy studies reporting the adenoma prevalence by age. Using multilevel logistic regression, we examined how the adenoma prevalence by age differed between individuals with and without a family history of colorectal cancer. We excluded members of families with a known genetic disorder.

RESULTS

Thirteen colonoscopy studies were identified. The adenoma prevalence was significantly higher in individuals with a family history than in those without (OR 1.7, 95% CI 1.4-3.5). The adenoma prevalence increased with age (OR per year of age 1.06, 95% CI 1.05-1.07). The age trend did not differ significantly between the two groups.

CONCLUSION

Individuals with a family history of colorectal cancer have a considerably higher prevalence of adenomas compared to individuals without a family history. This is consistent with their increased risk of colorectal cancer.

Clinicopathological features of colorectal cancer in patients under 40 years of age

OBJECTIVE

The aim was to identify the clinical factors and tumour characteristics that predict survival in patients younger than 40 years with colorectal adenocarcinoma.

MATERIAL AND METHODS

Fifty-nine patients with colorectal cancer aged under 40 years were identified from a computer database, and their clinical variables were analysed. The factors predicting long-term survival were compared by both univariate and multivariate analysis.

RESULTS

The prevalence of positive family history of cancer was 27%, and predisposing factors were present in 31% of the patients. All patients underwent resective surgery, 76% radical and 24% palliative resection, and their 5-year survival was 59% and mean survival +/-75 months. The recurrence rate after radical resection was 38% being 14%, 30%, 78% and 100% in Dukes classes A, B, C and D. The cumulative 5-year survival of men, 45%, was significantly worse than that of women, 73%, and this phenomenon was closely related to more distended lymphatic and venous invasion of cancer in men. Kaplan-Meier estimates showed that gender, Dukes staging, grade of tumour, lymphatic invasion, the number of lymph nodes with metastases, venous invasion and size of tumour were significant predictors of survival, but in Cox regression model, only venous invasion was the independent prognostic factor of survival.

CONCLUSIONS

Young men with colorectal cancer in Northern Finland have poorer prognosis than women. Venous invasion is an independent predictor of survival.

The association of tumor microsatellite instability phenotype with family history of colorectal cancer

Family history is a strong predictor of colorectal cancer risk; however, a diagnosis of colorectal cancer among first-degree relatives has not been systematically investigated as a function of the colorectal cancer molecular subtypes related to tumor microsatellite instability (MSI) status. We investigated whether the observable familial colorectal cancer risks differed according to tumor MSI subtypes, stratified as MSI-High (>30% instability), MSI-Low (<30% instability), and MSS (no instability). Data from 3,143 population-based colorectal cancer cases from five institutions were assessed for family history according to the Amsterdam criteria and the Bethesda guidelines, age at diagnosis, sex, tumor location, and MSI status. The distribution of patient characteristics by MSI status was compared using polytomous logistic regression. Overall, 2.8% colorectal cancer cases met the Amsterdam criteria and 37% met the Bethesda guidelines. There were 14% MSI-High, 13% MSI-Low, and 73% MSS colorectal cancers. MSI-High (P<0.0001) and MSI-Low tumors (P=0.01) were more proximally located than MSS tumors. MSI-High tumors were more common among females (P<0.001). The highest proportion of MSI-High tumors occurred in cases<40 years of age whereas the age-dependent distribution of MSI-Low tumors was unchanged. MSI-High tumors showed a statistically significant association with increasing numbers of first-degree relatives with colorectal cancer (P=0.002); this association disappeared, however, when MSI-High cases meeting Amsterdam criteria were removed from the analysis. MSI-Low tumors did not show a similar association with family history of colorectal cancer. Familial risk associated with MSI-High tumors is primarily driven by the Amsterdam-criteria patients. MSI-Low tumors may represent a distinct subtype of colorectal cancer with respect to certain epidemiologic variables studied here.

Colonoscopy in asymptomatic individuals with a family history of colorectal cancer

BACKGROUND

This study was performed to evaluate the use of total colonoscopy as the optimal screening test in asymptomatic individuals with a family history of colorectal cancer (CRC).

METHODS

Colonoscopy was performed in 249 asymptomatic individuals who had one or two first-degree relatives (FDRs) with CRC; individuals with three or more FDRs with CRC were excluded.

RESULTS

Eighty-six colonic lesions were found in 51 individuals (51 of 249; 20.5%). Among these 51 subjects, 27 had neoplastic polyps (n = 38) and 29 had metaplastic polyps (n = 44). Although no invasive cancer was detected, in 14 individuals the lesions had a high malignancy potential because of their size and histopathology. We did not confirm a statistically significant difference in the incidence of neoplastic polyps according to the number of affected FDRs. Finally, the presence of metaplastic polyps was a very strong indication for the concomitant presence of metaplastic polyps (P <.0001).

CONCLUSIONS

Total colonoscopy is the optimal screening procedure for the examination of asymptomatic individuals with a family history of CRC.

Applying evidence-based guidelines improves use of colonoscopy resources in patients with a moderate risk of colorectal neoplasia

OBJECTIVES

To determine whether applying National Health and Medical Research Council (NHMRC) guidelines for colorectal cancer prevention would reduce the number of follow-up colonoscopies.

DESIGN

A prospective audit of colonoscopic surveillance decisions before and after the intervention.

SETTING

The endoscopy suite at a metropolitan tertiary hospital three months before and after January 2000.

INTERVENTION

Dissemination of NHMRC guidelines, and supervision of application of the guidelines by a nurse coordinator.

SUBJECTS

We compared colonoscopic surveillance decisions before and after the intervention in two groups of 100 consecutive patients after polypectomy and in two groups of 50 consecutive patients with a family history of colorectal cancer after a normal colonoscopy.

MAIN OUTCOME MEASURES

Change in concordance of decisions with NHMRC guidelines; and effect on number of follow-up colonoscopies.

RESULTS

After the intervention, the proportion of postpolypectomy surveillance decisions matching the guidelines increased from 37% to 96% (P < 0.05). The mean time to repeat colonoscopy after polypectomy increased from 2.7 to 3.5 years (P < 0.005) (ie, a 23% reduction in the number of postpolypectomy surveillance colonoscopies performed per year). Likewise, the proportion of family-history surveillance decisions matching the guidelines increased from 63% to 96%. Adhering to the guidelines resulted in a 17% reduction in colonoscopies performed on the basis of a family history of colorectal cancer.

CONCLUSIONS

Supervised application of evidence-based guidelines to a colorectal cancer surveillance program significantly reduces the number of surveillance colonoscopies performed.

Family history of colorectal adenomatous polyps as a risk factor for colorectal cancer

The aim of this study was to evaluate the risk of common colorectal cancer among first-degree relatives of patients with colorectal adenomatous polyps. In a population screening programme, 59406 subjects underwent an immunochemical faecal occult blood test. In a medical check-up-based cross-sectional study, 6139 subjects had a colonoscopic examination. They were divided into two groups, according to the results of a questionnaire on family history of colorectal adenomatous polyps, and the detection rates for colorectal cancer were compared in the groups positive or negative for a family history of colorectal adenomatous polyps. In the screening programme-based cross-sectional study, the detection rate for colorectal cancer was 0.57% (95% confidence interval (CI): 0.38-0.76) and 0.15% (95% CI: 0.12-0.18) in subjects with and without a family history of colorectal adenomatous polyps, respectively, showing a significant difference in the detection rate for colorectal cancer between the two groups (P<0.05). In the medical check-up-based cross-sectional study, the detection rate for colorectal cancer was 2.31% (95% CI: 1.15-3.47) and 0.53% (95% CI: 0. 34-0.72) in subjects with and without a family history of colorectal adenomatous polyps, respectively, indicating a significant difference between the two groups (P<0.05). These findings indicate that first-degree relatives of patients with colorectal adenomatous polyps have an elevated risk for common colorectal cancer, and that people with a family history of colorectal adenomatous polyps should be considered as a priority group for colorectal cancer screening.

Yield from colonoscopic screening in people with a strong family history of common colorectal cancer

BACKGROUND AND AIMS

People with a strong family history of common (so-called 'sporadic') colorectal cancer are generally advised to undergo colonoscopic screening, but the starting age for this is unclear. An audit was performed to study the age-related yield of screening colonoscopy in this risk group.

METHODS

A prospective audit of the outcome of screening colonoscopy was performed on a cohort of 232 people with a strong family history of common colorectal cancer. All were registrants in a familial bowel cancer service solely because of their family medical history. They had no bowel symptoms and no prior endoscopic investigation of the large bowel.

RESULTS

Neoplastic lesions were detected by using colonoscopy in 33 participants. In 27 participants, the major lesion was a small tubular adenoma, four had an advanced adenoma and two had cancer. More neoplastic (P= 0.02) and advanced neoplastic (P= 0.03) lesions were found in those patients aged > or = 50 years. Only one advanced adenoma was detected in a participant below the age of 50 years.

CONCLUSION

The yield from screening colonoscopy in young people (< 50 years) with a strong family history of common colorectal cancer is low, placing doubt on the need for colonoscopic screening before the age of 50 years.

Does hereditary nonpolyposis colorectal cancer explain the observed excess risk of colorectal cancer associated with family history?

Several studies have found an increased risk of colorectal cancer associated with a family history of colorectal cancer. Some studies, although not all, have also suggested that family history of colorectal cancer may be a risk factor for adenomatous polyps. Hereditary nonpolyposis colorectal cancer is a known genetic syndrome predisposing to colorectal cancer. The hypothesis of this paper is that the preponderance of the genetic or familial risk for colorectal cancer in the United States is mediated by hereditary nonpolyposis colorectal cancer. To test this hypothesis, I have incorporated what is known about hereditary nonpolyposis colorectal cancer into a genetic model that generates probabilities of family clustering of colorectal cancer. Using this model, which assumes that all familial risk for colorectal cancer is due to hereditary nonpolyposis colorectal cancer, the expected relative risks for colorectal cancer (and adenomas) associated with given types of family histories were calculated. The relative risks predicted by the model fairly closely matched the results found in the literature, especially those reported from a large cohort study. As observed in several studies, the model predicts that relative risks decrease sharply with age. In contrast to the elevated risk for colorectal cancer, the model predicts no elevated risk for adenomas associated with family history of colorectal cancer.

Colonoscopic screening in first-degree relatives of patients with 'sporadic' colorectal cancer: a case-control study. The Association Nationale des Gastroentérologues des Hôpitaux and Registre Bourguignon des Cancers Digestifs (INSERM CRI 9505)

BACKGROUND & AIMS

A screening policy has not been well defined in first-degree relatives of patients with sporadic colorectal cancer. This study estimated the risk of colorectal adenoma in a cohort of individuals with only 1 affected first-degree relative.

METHODS

A total of 476 first-degree relatives (age, 40-74 years) of 195 patients with sporadic colorectal cancer were offered a colonoscopy. Each examined relative was matched with 2 controls for age, sex, symptoms, and center. The prevalence of colorectal adenomas was compared using a multiple logistic regression analysis.

RESULTS

In 185 relatives, odds ratios were 1.5 (95% confidence interval [CI], 1.0-2.4) for adenomas, 2.5 for large adenomas (95% CI, 1.1-5.4), 1.2 for small adenomas (95% CI, 0.7-1.9), and 2.6 (95% CI, 1.3-5.1) for high-risk adenomas (> or = 1 cm in size and/or with a villous component). The prevalence of high-risk adenomas in relatives was higher when the index patient was younger than 65 years, was male, and had distal rather than proximal cancer.

CONCLUSIONS

Subjects with only 1 affected first-degree relative are at increased risk for developing large adenomas.

Shared tumor antigens in colorectal carcinoma and neuroendocrine tumors

ND4 monoclonal antibody recognizes a tumor marker found on poorly differentiated colorectal cancer. We demonstrate its expression in 25% of gastrointestinal neuroendocrine tumors, which also express CEA in 37% of cases. As in colorectal cancer the ND4 marker is predominantly membrane bound in a colonic neuroendocrine tumor cell line, LCC-18 (p < 0.05). The ND4 marker is absent in a poorly differentiated colorectal cancer cell line that does not express CEA or other tumor antigens. Shed antigen in the serum of patients with neuroendocrine tumors is detected in only five of seven patients with the carcinoid syndrome and two of four of those without evidence of the syndrome. However, the reactivity was less in the patients with localized disease, and this test is unlikely to be of diagnostic utility in this group of patients. The sharing of this antigen in colorectal cancer and neuroendocrine tumors is not universal, but does support the common-cell progenitor theory for the origin of these tumors.

Clustering of colorectal cancer in families of probands under 40 years of age

Although sporadic colorectal cancer (CRC) is relatively uncommon in the young, it may constitute an elevated genetic risk for CRC in these individuals.

PURPOSE

This study was designed to determine extent of colorectal cancer in families of probands under 40 years of age.

METHODS

Medical records of all consecutive patients, 40 years of age or younger at the time of CRC surgery, during the time period 1986 to 1994 were examined. Cases of familial adenomatous polyposis and ulcerative colitis were excluded. Via interviews of surviving probands or nearest relatives, dates of birth and death, causes of death, and diagnosis of cancer were recorded on all first-degree relatives (parents, siblings, and offspring), second-degree relatives (grandparents, aunts, and uncles), and any other relatives.

RESULTS

A total of 128 patients, 40 years of age or less at time of CRC resection, were identified. Of these, 45 probands/families were reached by phone, and 45 detailed family histories were obtained. Age range of these 45 probands was 19 to 40 (mean, 33.1) years. In 25 families there was no history of CRC in first-degree, second-degree, or third-degree relatives. Eight of 45 probands (17.8 percent) had at least one first-degree relative with CRC, and three of these eight families fulfilled the Amsterdam criteria for hereditary nonpolyposis colorectal cancer (HNPCC). In all three families, inheritance of CRC appeared to segregate with the maternal side of the family. In addition, 5 of 43 non-HNPCC probands had at least one first-degree, second-degree, or third-degree relative less than 40 years of age, at time of CRC diagnosis.

CONCLUSION

Ascertainment of a detailed family history in early age of onset CRC patients identifies frequent familial clustering of CRC and HNPCC in 17.8 percent of cases.

Prolonged hypergastrinemia does not increase the frequency of colonic neoplasia in patients with Zollinger-Ellison syndrome

Whereas considerable experimental evidence suggests chronic hypergastrinemia can increase the occurrence of colonic neoplasia, the risks in man remain unclear. Zollinger-Ellison syndrome (ZES) is associated with marked plasma elevation of all forms of gastrin and, because of its prolonged course, has been shown to be an excellent model disease to study the effects of chronic hypergastrinemia in man. To determine whether profound chronic hypergastrinemia affects the occurrence of colonic dysplasia and neoplasia, 97 consecutive patients with ZES were studied. All patients underwent colonoscopic examination to the cecum, and the location, size, and type of polyps/tumors were determined. The patients had a mean fasting gastrin level 31 times above normal and a mean disease duration of 10 years; 17/97 (18%) had adenomatous polyps, 67/97 (69%) no adenomatous polyps, and 2/97 (2%) had colonoscopy and/or autopsy studies fo asymptomatic controls. Stratification by age or gender, presence of MEN-I, tumor extent, and duration of degree of hypergastrinemia did not increase prevalence. This study shows that despite prolonged, profound hypergastrinemia, no increased rate of colonic neoplasia (polyps or cancer) was noted. These data suggest that the development of hypergastrinemia secondary to continuous use of H+,K+-ATPase inhibitors for as long as 10 years is unlikely to cause an increased risk of developing colonic neoplasia in man.

Risk of colorectal cancer in the families of patients with adenomatous polyps. National Polyp Study Workgroup

BACKGROUND

The adenoma-adenocarcinoma sequence in colorectal cancer suggests an increased risk of colorectal cancer in the families of patients with adenomatous polyps.

METHODS

A random sample of participants in the National Polyp Study who had newly diagnosed adenomatous polyps were interviewed for information on the history of colorectal cancer in their parents and siblings. The risk of colorectal cancer in family members was analyzed according to the characteristics of the patients with adenomas and in comparison with a sample of patients' spouses, who served as controls.

RESULTS

Among the patients with adenomas, 1199 provided information on whether they had a family history of colorectal cancer. After the exclusion of families for which information was incomplete and of 48 patients who had been referred for colonoscopy solely because they had a family history of colorectal cancer, there were 1031 patients with adenomas, 1865 parents, 2381 siblings, and 1411 spouse controls. The relative risk of colorectal cancer, adjusted for the year of birth and sex, was 1.78 for the parents and siblings of the patients with adenomas as compared with the spouse controls (95 percent confidence interval, 1.18 to 2.67). The relative risk for siblings of patients in whom adenomas were diagnosed before 60 years of age was 2.59 (95 percent confidence interval, 1.46 to 4.58) as compared with the siblings of patients who were 60 or older at the time of diagnosis and after adjustment for the sibling's year of birth and sex and a parental history of colorectal cancer. The risk increased with decreasing age at the time of the diagnosis of adenoma (P for trend < 0.001). The relative risk for the siblings of patients who had a parent with colorectal cancer, as compared with those who had no parent with cancer, was 3.25 (95 percent confidence interval, 1.92 to 5.52), after adjustment for the sibling's year of birth and sex and the patient's age at diagnosis.

CONCLUSIONS

Siblings and parents of patients with adenomatous polyps are at increased risk for colorectal cancer, particularly when the adenoma is diagnosed before the age of 60 or--in the case of siblings--when a parent has had colorectal cancer.

Clinical impact of colonoscopic screening in first-degree relatives of patients with hereditary non-polyposis colorectal cancer

Sixty-one asymptomatic individuals with an affected first-degree relative from five large hereditary non-polyposis colorectal cancer (HNPCC) kindreds were screened by colonoscopy. Neoplasms were found in nine (15 per cent) of 61 individuals on the first screen. Five subjects had a single adenoma while two had two adenomas each. There were two patients (3 per cent) with malignant neoplasms: one with a Dukes B adenocarcinoma and one with synchronous Dukes C adenocarcinomas in the caecum and ascending colon. These findings support the hypothesis that adenomas do not occur in large numbers in HNPCC families but, because of the high malignant conversion rate, biennial colonoscopy with removal of polyps seen is recommended.

The risk of adenomatous polyps in asymptomatic first-degree relatives of persons with colon cancer

BACKGROUND & AIMS

Increasing evidence indicates that inherited susceptibility is important in the pathogenesis of colorectal neoplasia. The aim of this study was to clarify whether having only one first-degree relative with colorectal cancer increases the risk of developing adenomatous polyps and whether total colonoscopy is an appropriate screening measure in these patients.

METHODS

The frequency of such a history was evaluated in 397 asymptomatic patients who underwent total colonoscopy. Of these patients, 155 had colorectal polyps and the remaining 242 did not have polyps.

RESULTS

Among polyp cases, 27 of 155 (17.4%) had a positive history; among those without polyps, 12 of 242 (5.0%) had a positive history. Alternatively expressed, 27 of 39 patients (69%) with family history and 128 of 358 patients (36%) without family history had adenomas. The estimated risk for polyps associated with family history was 1.9. Among polyp cases, 14 of 27 patients (51.9%) with family history and 32 of 128 patients (25.0%) without family history had only proximal polyps (chi 2 test; P = 0.006; odds ratio, 3.2), In the same groups, frequency of high-grade dysplasia was 8 of 27 patients (29.6%) and 16 of 128 patients (12.5%), respectively (chi 2 test; P = 0.04; odds ratio, 2.9).

CONCLUSIONS

Relative to subjects with no family history, asymptomatic patients with one first-degree relative with colorectal cancer had nearly double the risk of developing adenomatous polyps, greater frequency of severely dysplastic lesions, and significantly higher frequency of proximal polyp location. This suggests that total colonoscopy screening is indicated in these subjects.

The role of colonoscopy in screening persons with family history of colorectal cancer

First-degree relatives of colorectal cancer patients are at increased risk for developing colorectal neoplasms. In order to assess the potentiality of colonoscopy screening in this high-risk population, 213 asymptomatic family members (age range 30-69 years, mean 42.8 years) of those patients with colorectal cancer received colonoscopic examination at Chang-Gung Memorial Hospital from April 1992 to May 1994. Twenty-eight persons with 42 lesions (polyps or cancer) were identified, including 28 adenomas, nine hyperplastic polyps and five adenocarcinomas. The positive detection rate was 9.9% for adenoma and 2.3% for cancer. Colorectal neoplasms afflicted males more frequently than females (16.7 vs 5.7%, P < 0.05) and occurred less frequently in those < 40 years of age (5.5 vs 17.2%, P < 0.05). Forty-two per cent of the detected neoplastic lesions were beyond the reach of 60 cm flexible sigmoidoscopy and 36% of adenomas were < 0.5 cm in size and would be missed if patients were screened by air contrast barium enema. Cost analysis revealed that the charges of both screening colonoscopy and screening flexible sigmoidoscopy/air contrast barium enema were approximate. Colonoscopy also has a high acceptability and safety. It appears appropriate to use colonoscopy, rather than flexible sigmoidoscopy or air contrast barium enema, as an initial screening procedure for persons with a family history of colorectal cancer, especially those > 40 years of age.

Variables associated with the risk of colorectal adenomas in asymptomatic patients with a family history of colorectal cancer

The results of screening individuals referred to the Family Cancer Clinic at St Mark's Hospital from 1986 are presented. Colonoscopy was performed in 644 asymptomatic individuals (from 436 families) with a family history of colorectal cancer. Sixty nine (15.8%) of the families fulfilled the Amsterdam criteria for the hereditary non-polyposis colorectal cancer syndromes (HNPCC). Seven cases of colorectal cancer were diagnosed at an average age of 49 years; six at Dukes's stage A and one at stage C, four in subjects from Amsterdam criteria families. One hundred and forty four (22.4%) subjects had one or more adenomas. The prevalence of adenomas in the subjects from Amsterdam criteria families was 34 of 127 (26.8%) compared with 110 of 517 (21.3%) in those from other families; the age and sex adjusted odds ratio (OR) was 1.76 (p = 0.02). Factors influencing the prevalence of adenomas in screened individuals were evaluated. Multivariate analysis showed that independent variables significantly related to the risk of adenomas were: age (p < 0.0001), sex (p = 0.0002), and the number of generations (> or = 2 v 1) of relatives affected by either colorectal cancer or adenomas (p = 0.0006). The latter variable was more highly predictive of the probability of finding an adenoma at colonoscopy than a family history of two generations with cancer only (p = 0.056). The OR of having colorectal adenomas increased with age, by about twofold for each decade, and was twice as high in men than women, and in subjects with two or more generations relative to those with one generation affected by colorectal cancer or adenomas. Six of seven patients with cancer and 46 of 144 (31.9%) with adenomas had lesions proximal to the splenic flexure only. The proportion of individuals with proximal adenomas only was 47.1% in Amsterdam criteria families and 27.3% in the others (p=0.03). These findings support the view that colonoscopy rather than sigmoidoscopy is the method of choice for screening high risk groups.

Should relatives of patients with colorectal cancer be screened? A critical review of the literature

PURPOSE

The objective of our investigation was to attempt to address the controversial issue concerning index screening and surveillance of relatives of patients with colorectal cancer and to identify those areas of research that should be considered in future studies.

METHODS

Relevant literature was reviewed concerning the screening of asymptomatic first-degree relatives of patients with colorectal cancer not associated with the rare autosomal dominant inherited colorectal cancer syndromes.

RESULTS

The data reviewed suggest that there is an increased risk of colorectal neoplasia in this population and a significantly higher yield of adenomas and carcinomas when colonoscopy is used for index screening. However, significant variability in study design and screening protocols and inconsistencies in data presentation make clinical interpretation and data analysis confusing and difficult.

CONCLUSIONS

There is a critical need for standardization in future studies. Furthermore, as there are no studies that document decreased overall mortality from colorectal cancer in first-degree relatives as a result of screening, the decision as to whether to screen this population needs to be based on future prospective controlled trials.

Does acromegaly really predispose to an increased prevalence of gastrointestinal tumours?

OBJECTIVE

The few published prospective studies suggest a strong association of colonic tumours with acromegaly, but include small numbers of patients. In addition, the upper gastrointestinal tract of these patients has never been prospectively studied. The aim of the present study was to investigate the incidence of gastric and colonic tumours in a large cohort of acromegalic patients.

DESIGN

Acromegalic patients consecutively admitted to an Endocrinology Department for diagnosis and follow-up, were submitted to gastroscopy and colonoscopy, to identify those harbouring gastrointestinal tumours.

PATIENTS

Over a 5-year period, 54 out of 61 patients (78% with active disease) received colonoscopy and 42 out of 61 gastroscopy. No patient had a past history of gastrointestinal malignancy.

MEASUREMENTS

All polypoid lesions found at colonoscopy and gastroscopy were separately recorded and biopsied.

RESULTS

No case of gastrointestinal cancer or gastric polyp was discovered. Nineteen patients (35%) had 1-8 colonic polyps, including 5 (9.3%) with adenomas. When compared to patients with a normal colon, those with polyps were significantly older (44.5 +/- 14.2 vs 52.1 +/- 10.9 years, P = 0.047), but the duration of acromegaly (10.8 +/- 8.4 vs 10.9 +/- 7.1 years, P = 0.9) and the number of patients with active disease were similar in both groups.

CONCLUSIONS

Acromegalic patients do not have an increased incidence of gastric tumours. The observed significant variation in the prevalence of colonic adenomas (9-35%, P = 0.03) and cancer (0-15%, P = 0.017), between our patients and those of the published prospective studies with similar demographic characteristics, suggest that environmental and hereditary factors may be more important than the presence of acromegaly.

Hereditary nonpolyposis colorectal carcinoma (HNPCC): clinical application of molecular diagnostic testing

An increased risk of colorectal cancer amongst close relatives of afflicted patients has been recognized for some time. Hereditary nonpolyposis colorectal cancer (HNPCC) represents an extreme example of this risk, in which single-gene inheritance predisposes relatives of affected family members. Approaches to surveillance and management of subjects at greater or lesser heritable risk have been evolving in the past two decades, but these efforts have suffered due to our inability to better characterize and quantify that risk. Recent discovery of susceptibility loci that are linked to disease in HNPCC has already begun to refine our understanding of the pathogenesis of the disease. At a clinical level, these advances now offer an improved ability to recognize carriers of the condition. Speculation is provided as to the probable utility of genetic testing in groups with varying strengths of colorectal cancer familiality. Notions of how positive and negative tests might be applied to surveillance and treatment are explored.

Screening strategies for colorectal cancer

The efficacy of screening for colorectal cancer has not been established. Policy-making organizations differ in recommendations for asymptomatic and high-risk groups because of the inadequacy of current evidence. A critical appraisal of the current evidence for screening for colorectal cancer and a discussion of the aims and pitfalls of screening programs are presented.

The National Polyp Study. Design, methods, and characteristics of patients with newly diagnosed polyps. The National Polyp Study Workgroup

The National Polyp Study (NPS) is a multicenter prospective randomized trial designed to evaluate follow-up surveillance strategies in patients who have undergone polypectomy for the control of large bowel cancer. The study design was developed by a joint research committee from American Gastroenterological Association, the American Society for Gastrointestinal Endoscopy, and the American College of Gastroenterology. Subjects who met the eligibility criteria were randomized into two different treatment arms. Eligibility criteria included: removal of one or more adenomas; complete colonoscopy; no prior polypectomy, inflammatory bowel disease, or familial polyposis; and no history of colon cancer. The treatment arms consisted of a frequent follow-up (1 and 3 years after initial polypectomy) and a less frequent follow-up (3 years). Follow-up examinations included fecal occult blood tests, air-contrast barium enema, and colonoscopy. The latter was done on 9112 referred patients at the seven participating centers from November 1980 until February 1990 who had no history of polypectomy, colon cancer, familial polyposis, or inflammatory bowel disease. Of these patients, 4763 (52.3%) had no polyps; 549 (6.0%) had an invasive cancer; 776 (8.5%) had nonadenomatous polyps; 208 (2.3%) had incomplete examinations; 184 (2.0%) had other findings; and 2632 (28.9%) had one or more adenomas, of which 1418 (53.9%) were randomized to one of the two treatment arms. This article reports the background, rationale, objectives, methods, and organization of this study and includes patient characteristics on initial presentation. Future data provided by the NPS may help in the development of recommendations for surveillance guidelines for such patients. This study also provides a framework to address questions regarding the natural history of adenomas and their relationship with colorectal cancer.

Colonoscopic screening examination of relatives of patients with colorectal cancer. I. A comparison with an endoscopically screened normal population

First-degree relatives (n = 206) of patients operated on for colorectal cancer (CRC) (n = 181) were offered a colonoscopic screening examination; 169 relatives (82%) attended. The findings were compared with those in a normal population sample with no CRC in first-degree relatives (n = 308), aged 50-59 years, who had been screened by means of flexible sigmoidoscopy. Three carcinomas and 176 polyps were found in 56 of 95 male relatives (57%) and 34 of 74 female relatives (46%). The adenoma prevalence rate was 37 (39%) and 26 (35%) for male and female relatives, respectively. In the 50- to 59-year age group, the adenoma prevalence rates for both sexes collectively and for women separately were significantly higher among relatives than among the population without CRC relatives. Hyperplastic polyps were larger, whereas adenomas were similar in size among relatives compared with the normal population. Colonoscopy may be a suitable method of choice for screening first-degree relatives of patients with CRC.

Screening for large bowel neoplasms in individuals with a family history of colorectal cancer

Logistical problems associated with population screening for colorectal cancer are identified and the possibility of targeting screening to those with a familial predisposition to the disease is discussed. Evidence for a substantial genetic effect on the overall incidence of colorectal cancer is reviewed. The screening detection rate of colorectal neoplasms in relatives of patients with colorectal cancer has been shown to be higher than that expected in a non-selected population; the evidence that polypectomy will reduce future colorectal cancer risk in such individuals is explored. Recent advances in the molecular genetics of colorectal cancer susceptibility are reviewed; it is possible that a genetic test might be developed in the future which could identify at least a proportion of those at risk. Excluding financial considerations, the risk-benefit ratio of colonoscopy in a screened population is intimately related to the remaining risk of colorectal cancer in those who undergo the examination. At present, patients undergoing colonoscopy to investigate a positive faecal occult blood (FOB) test as part of a population-based screening programme include individuals with a familial predisposition as well as those without. About 20 per cent of all cases of colorectal cancer are associated with an obvious genetic predisposition, and the risk of cancer in their relatives is high. Because false positives occur with Haemoccult, the residual risk to the population who are FOB positive but do not have a familial trait may be sufficiently low that the dangers of colonoscopy could outweigh the potential benefits. Scotland has a high incidence of colorectal cancer, and analysis of recent Scottish incidence data shows an actuarial lifetime risk of developing this disease of one in 23 for men and one in 33 for women. As a family history of the disease increases that risk by two to four times and the neoplasms arise throughout the colon in such a group, there may be a case for offering colonoscopy to all first-degree relatives of those under 50 years of age at diagnosis, if not of all index cases of colorectal cancer.

Colonoscopic screening for neoplasms in asymptomatic first-degree relatives of colon cancer patients. A controlled, prospective study

Individuals with a family history of colorectal cancer are believed to be at an increased risk of developing colorectal neoplasia. To estimate this risk and the potential yield of screening colonoscopy in this population, we recruited and prospectively colonoscoped 181 asymptomatic first-degree relatives (FDR) of colorectal cancer patients and 83 asymptomatic controls (without a family history of colorectal cancer). The mean ages for the FDR and control groups were 48.2 +/- 12.5 and 54.8 +/- 11.0, respectively. Adenomatous polyps were detected in 14.4 percent of FDRs and 8.4 percent of controls. Although 92 percent of our FDRs had only one FDR afflicted with colon cancer, those subjects with two or more afflicted FDRs had an even higher risk of developing colonic adenomas (23.8 percent) than those with only one afflicted FDR (13.1 percent). A greater proportion of adenomas was found to be beyond the reach of flexible sigmoidoscopy in the FDR group than in the controls (48 percent vs. 25 percent, respectively). Logistic regression analysis revealed that age, male sex, and FDR status were independent risk factors for the presence of colonic adenomatous polyps (RR = 2.32, 2.86, and 3.49, respectively; P less than 0.001). Those at greatest risk for harboring an asymptomatic colonic adenoma are male FDRs over the age of 50 (40 percent vs. 20 percent for age-matched male controls). Based on probability curves, males with one FDR afflicted with colon cancer appear to have an increased risk of developing a colonic adenoma beginning at 40 years of age. Our results document, for the first time, an increased prevalence of colonoscopically detectable adenomas in asymptomatic first-degree relatives of colon cancer patients, as compared with asymptomatic controls, and support the use of colonoscopy as a routine screening tool in this high-risk group.

Frequency of familial colorectal cancer

Familial clustering of cancer is not uncommon. The frequency of familial colorectal cancer was estimated by taking family histories from 100 patients presenting with apparently sporadic colorectal cancer. Compared with controls, the relative risk of a positive family history for colorectal cancer was 4.6. Life-table methods were used to examine the observed to expected mortality from colorectal cancer. Overall there was a fourfold increase in mortality rate (P less than 0.0001), which was greatest in female relatives of patients with colonic cancer (P less than 0.001). Three families with dominant inheritance of colorectal cancer and one family with Lynch type II syndrome were identified. Nine per cent of patients had siblings who had developed colorectal cancer a median of 4 years before the diagnosis of the index patient (range 1-17 years). It is recommended that a careful family history should be obtained from all patients with colorectal cancer. Where a positive history is obtained a geneticist may determine empirical risks for the development of colorectal cancer and the appropriate method of surveillance may be selected.

Is colonoscopic screening appropriate in asymptomatic patients with family history of colon cancer?

Colonoscopy has been advocated by some investigators as the most appropriate means of screening asymptomatic patients with a positive family history of colorectal cancer. However, results of such screening have been widely disparate. The purpose of this study was to evaluate the yield of colonoscopy in a cohort of completely asymptomatic individuals with one or two first-degree relatives with a history of colorectal cancer and to compare this yield with that of colonoscopy in a group of patients with apparent anal bleeding. Patients with possible genetic disorders, such as familial polyposis, were excluded. A total of 160 asymptomatic patients and a comparison group of 137 patients with nonacute anorectal bleeding underwent colonoscopy. Colonoscopy was completed in 143 of the 160 study patients (89 percent) and in all of the comparison patients and did not result in any complications. Twenty-two adenomas were found in 17 study patients (10.6 percent); 16 of the 22 adenomas were less than 1 cm in size. In the comparison group, eight adenomas were identified (5.8 percent of patients). No cancers were identified. The difference in polyp frequency between groups was not significant. The relatively low yield of colorectal neoplasms discovered at colonoscopy in this study may in part be due to the small sample size or to the strict criteria used to define these asymptomatic patients but does not lend strong support to the notion that colonoscopy is an appropriate first step in screening the asymptomatic patient with one or two first-degree relatives with colon cancer.

Colonoscopic screening of asymptomatic patients with a family history of colon cancer

The records of 201 asymptomatic patients who underwent colonoscopy based solely on a family history of colon cancer were reviewed. Eighty-five patients (42 percent) had a total of 166 lesions. Fifty-four (27 percent) patients of the screened population had neoplastic lesions, while 31 (15 percent) patients had nonneoplastic polyps. Four carcinomas were found. Twenty-five of the patients with polyps (29 percent) had no polyps distal to the splenic flexure; these proximal polyps (and two carcinomas) would have been missed on screening with fiberoptic sigmoidoscopy. Nineteen of these 25 patients had polyps smaller than 0.5 cm, which likely would have been missed with contrast enemas. Almost one half (47 percent) of all polyps discovered at screening colonoscopy were proximal to the descending colon. Only one patient younger than 40 years old had adenomas. The yield of polyps and cancer in patients with familial risk indicates screening colonoscopy should be considered after age 40.

Bile acids and the increased risk of colorectal tumours after truncal vagotomy

An association between colorectal cancer and previous peptic ulcer surgery is reported. In a prospective screening study, 100 asymptomatic patients (80 men and 20 women) who had undergone truncal vagotomy at least 10 years previously were investigated by barium enema, colonoscopy and gallbladder ultrasonography. Control data were obtained from forensic autopsy subjects. The incidence of neoplasms greater than or equal to 1.0 cm in the vagotomized group was 14 per cent (11 adenomas, 3 carcinomas) and 3 per cent in controls (P = 0.01). Duodenal bile obtained at endoscopy from 21 vagotomized patients with normal gallbladders and from 21 control patients undergoing endoscopy was analysed by high performance liquid chromatography. The mean percentage of cholic (CA), chenodeoxycholic (CDCA), deoxycholic (DCA) and lithocholic (LCA) acids in the bile of vagotomized patients was 32.3, 45.6, 20.7 and 1.4 per cent respectively compared with 45.3, 36.2, 17.9 and 0.7 per cent respectively in controls. The increased proportions of CDCA and LCA and decreased proportions of CA in the duodenal bile of vagotomized patients were significant (P less than 0.001; P = 0.02; P = 0.007). Abnormalities in bile acid metabolism may help to explain the increased risk of colorectal neoplasia 10 years after truncal vagotomy.

Energy imbalance and cancer of the breast, colon and prostate

In Western societies, energy imbalance is characterized by obesity and sedentary life styles and is associated with increased morbidity and mortality from all causes of cancer, including cancer of the breast, colon and prostate. The interrelationships of energy intake and energy retention, to energy expenditure and physical fitness need further investigation from the physiologic, metabolic, endocrine and genetic aspects of cancer development, since obesity, energy expenditure and cancer have a familial predisposition. The effects of exercise on estrogen and prostaglandin metabolism and their relationship to cancer development require further investigation. Although the exact amount and intensity of exercise that confers benefit is not known, physical activity and physical fitness are inversely associated with all-cause mortality, including cancer. These findings have important public health implications, because about one-third of persons in industrialized societies are quite sedentary, and the prevalence of low physical fitness is quite high. The balance between total energy intake and expenditure may be more important in cancer development than the intake of any given dietary component or energy source. Exercise increases prostacyclin and decreases the aggregation of platelets and possibly decreases the platelet derived growth factors (PDGF). One could speculate that exercise may in turn decrease the probability of developing colon cancer in those who are predisposed to it, since the SIS oncogene is in fact a variant of PDGF.