***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
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    Input: BACKGROUND A family history of colorectal cancer is recognized as a risk factor for the disease . However , as a result of the retrospective design of prior studies , the strength of this association is uncertain , particularly as it is influenced by characteristics of the person at risk and the affected family members . METHODS We conducted a prospect i ve study of 32,085 men and 87,031 women who had not previously been examined by colonoscopy or sigmoidoscopy and who provided data on first-degree relatives with colorectal cancer , diet , and other risk factors for the disease . During the follow-up period , colorectal cancer was diagnosed in 148 men and 315 women . RESULTS The age-adjusted relative risk of colorectal cancer for men and women with affected first-degree relatives , as compared with those without a family history of the disease , was 1.72 ( 95 percent confidence interval , 1.34 to 2.19 ) . The relative risk among study participants with two or more affected first-degree relatives was 2.75 ( 95 percent confidence interval , 1.34 to 5.63 ) . For participants under the age of 45 years who had one or more affected first-degree relatives , the relative risk was 5.37 ( 95 percent confidence interval , 1.98 to 14.6 ) , and the risk decreased with increasing age ( P for trend , < 0.001 ) . CONCLUSIONS A family history of colorectal cancer is associated with an increased risk of the disease , especially among younger people Abstract Purpose The purpose of the study was to investigate the impact of a family history ( FH ) of colorectal cancer ( CRC ) in first-degree relatives on the outcome of patients with CRC in a veterans ’ hospital in Taiwan . Methods Patients ( N = 3,383 ) with colorectal adenocarcinoma were studied ; pedigrees were collected prospect ively . Associations between FH and clinicopathologic variables were analyzed using linear-by-linear association . Survival was examined with Kaplan – Meier curves and the log-rank test . Results Two hundred ninety-seven patients ( 8.78 % ) had a first-degree relative with CRC . The average age of onset of CRC was 68.3 years in patients without a FH . This was significantly higher than the age of onset in patients with a FH ( 66.4 years — one first-degree relative with CRC ; 48.8 years — two or more first-degree relatives , P < 0.001 ) . Patients with more affected family members had a higher incidence of right-sided tumor ( P = 0.004 ) , metachronous cancer ( P = 0.034 ) , and less-advanced disease ( P = 0.044 ) . The 5-year overall survival was 83 % for patients with two or more first-degree relatives with CRC , 57 % for those with one first-degree relative , and 55 % for those without a FH ( P = 0.001 ) . The 5-year DFS was 91 % for patients with two or more first-degree relatives , 66 % for those with one first-degree relative , and 64 % for those without a FH of CRC ( P = 0.002 ) . In the multivariate analysis , TNM stage played the most independent prognostic factor , followed by FH ( P < 0.001 , hazard ratio = 1.52 ; 95 % confidence interval , 1.24–1.85 ) . Conclusions CRC patients with a family history of CRC had better survival than did those without a family history of CRC Gene frequency data , consisting of six red cell antigen loci , nine electrophoretic systems , and HLA-A and -B are reported for the Utah Mormon population . These are compared statistically to gene frequencies from at U.S. population , 13 European population s , and seven population s from three religious isolates . The Mormon gene frequencies are similar to those of their northern European ancestors . This is explained by the large founding size of the Mormon population and high rates of gene flow . In contrast , the religious isolates ( Amish , Hutterites , and Mennonites ) show marked divergence from their ancestral population s and each other , due to isolation and r and om genetic drift . The HLA loci and electrophoretic loci presented here yield sets of genetic distances that are highly correlated ( r = .734 ) and that both correspond closely to the actual geographic distances among the European population s. The genetic distances based on red cell antigen loci correspond less closely to the geographic distances and exhibit lower correlations with both the HLA and electrophoretic loci ( r = .524 and r = .565 , respectively ) Using a computerized genealogical data base , inbreeding coefficients were calculated for a sample of 435777 Utah Mormons . The population was divided into ten ten‐year birth cohorts ( 1846–1945 ) and 22 geographic subdivisions in order to assess temporal and spatial variation in inbreeding . The average inbreeding coefficient for this population is 0.000 106 . The average within‐groups r and om kinship coefficient is 0.000 312 , reflecting consanguinity avoidance . R and om kinship matrices were formed by estimating the average kinship within each spatial subdivision and between all pairs of subdivisions . These matrices were compared statistically with kinship matrices previously estimated using migration matrices and isonymy data . The isonymy approach consistently overestimates r and om and total inbreeding as well as Wright 's Fst . This can be attributed primarily to the assumption of monophyletic origin of surnames . The migration matrix method underestimates r and om inbreeding and Fst . This is due mainly to the assumption that outside immigrants are derived from a genetically homogeneous population . While the absolute values of the kinship coefficients estimated by each method differ substantially , the patterns of between‐groups kinship coefficients given by each method are highly congruent . Logistic and linear regression analyses of 85 235 marriages demonstrate that consanguinity is significantly dependent upon year of marriage , geographic distance between husb and 's and wife 's birthplaces , and the population size of husb and 's and wife 's birthplaces A family history of colorectal cancer may increase colorectal cancer risk by influencing adenoma growth or enhancing the formation of new lesions . Data of men from the prospect i ve Health Professionals Follow-Up Study who underwent an endoscopy between 1986 and 2004 were used to evaluate whether a family history of colorectal cancer is associated with adenoma multiplicity or advanced adenoma stage ( > or = 1 cm , histology with villous component or carcinoma in situ ) . 21.4 % of the 3,881 adenoma patients and 13.9 % of the 24,959 adenoma-free men had a first-degree relative with colorectal cancer . Thous and four hundred and ninety-six men were classified as having advanced and 1,507 as having nonadvanced adenomas . Six hundred and twenty-two men had multiple and 1,985 had single adenomas in the distal colon and rectum . A family history of colorectal cancer was similarly associated with advanced and nonadvanced adenomas [ multivariable odds ratio ( OR ) ( 95 % confidence interval ) : advanced vs. nonadvanced , 0.98 ( 0.82 - 1.17 ) , advanced vs. adenoma-free : 1.67 ( 1.47 - 1.91 ) , nonadvanced vs. adenoma-free : 1.70 ( 1.49 - 1.94 ) ] , although potential differences according to adenoma location were seen . A family history of colorectal cancer was more strongly associated with multiple distally located adenomas [ odds ratio ( 95 % confidence interval ) : multiple vs. single , 1.35 ( 1.09 - 1.68 ) , multiple vs. no distally located adenomas : 2.02 ( 1.67 - 2.44 ) , single vs. no distally located adenomas : 1.49 ( 1.32 - 1.68 ) ] . The number of adenomas was also positively associated with a family history of colorectal cancer . Our findings suggest that at the population level , heritable factors may be more important in earlier stages of adenoma formation than at stages of adenoma advancement for at least distally located adenomas Predictors of colorectal cancer have been extensively studied with some evidence suggesting that risk factors vary by subsite . Using data from 2 prospect i ve cohort studies , we examined established risk factors to determine whether they were differentially associated with colon and rectal cancer . Our study population included 87,733 women from the Nurses ' Health Study ( NHS ) and 46,632 men from the Health Professionals Follow Up Study ( HPFS ) .  Exposure information was collected via biennial question naires ( dietary variables were collected every 4 years ) . During the follow-up period ( NHS : 1980 to May 31 , 2000 ; HPFS : 1986 to January 31 , 2000 ) , we identified 1,139 cases of colon cancer and 339 cases of rectal cancer . We used pooled logistic regression to estimate multivariate relative risks for the 2 outcomes separately and then used polytomous logistic regression to compare these estimates . In the combined cohort , age , gender , family history of colon or rectal cancer , height , body mass index , physical activity , folate , intake of beef , pork or lamb as a main dish , intake of processed meat and alcohol were significantly associated with colon cancer risk . However , only age and sex were associated with rectal cancer . In a stepwise polytomous logistic regression procedure , family history and physical activity were associated with statistically significant different relative risks of colon and rectal cancer . Our findings support previous suggestions that family history and physical activity are not strong contributors to the etiology of rectal cancer . Future investigations of colon or rectal cancer should take into consideration risk factor differences by subsite The aggregation of colon , endometrial , ovarian , and possibly breast cancers in families has been described as a " cancer family syndrome " ( now called Lynch syndrome II ) . To determine if the familial clustering of these malignancies was more common in women with cancer than without , we analyzed data from the Iowa Women 's Health Study ( IWHS ) , a population -based sample of 41,837 women aged 55 - 69 years .  Self-reported information was collected on history of colon , uterine , ovarian , and breast cancers in female first-degree relatives . A family history of cancer of the breast ( odds ratio [ OR ] = 1.4 ) , colon ( OR = 1.3 ) , and uterus ( OR = 1.3 ) , but not ovary ( OR = 1.2 ) , was significantly more common among women with a personal history of any of these four cancers ( all P < 0.05 ) ; the pattern of the ORs suggested strongly that the clustering tended to be site-specific . Age-adjusted relative risks ( RR ) of incident colon cancer over 5 years of follow-up ( N = 237 ) were calculated with regard to family history . Colon cancer incidence was increased among women with a family history of breast ( RR = 1.3 ) , uterine ( RR = 1.4 ) , colon ( RR = 1.5 ) , and ovarian ( RR = 1.3 ) cancers , although none of the risk estimates achieved statistical significance . RR was , however , significantly related to the number of different cancer sites reported among family members ( Ptrend = 0.008 ) . These data on a representative sample of postmenopausal women suggest that family histories of colon , breast , uterine , and ovarian cancers are associated with an increased risk of cancer at the same site , but provide little support for the hypothesis that Lynch syndrome II is a non-r and om occurrence BACKGROUND Developing effective programs to promote colorectal cancer ( CRC ) screening requires underst and ing of the effect of healthcare system factors on access to screening and adherence to guidelines . METHODS This study assessed the role of insurance status , type of plan , the frequency of preventive health visits , and provider recommendation on utilization of CRC screening tests using a cross-sectional , r and om-digit-dial survey of 1002 Massachusetts residents aged > or = 50 . RESULTS A broad definition of CRC screening status included colonoscopy or barium enema ( screening or diagnostic ) within 10 years , flexible sigmoidoscopy ( FSIG ) within 5 years , and fecal occult blood testing ( FOBT ) in the past year as options ; 51.7 % of subjects aged 50 to 64 and 61.5 % of older subjects were current . The uninsured had the lowest current testing rate . Among insured participants , type of insurance had little impact on CRC testing ; older subjects enrolled in HMOs had marginally higher rates , although not statistically significant . Increased frequency of preventive health visits and ever receiving a physician 's recommendation for FSIG or ever receiving FOBT cards were associated with higher rates of CRC screening among both age groups . CONCLUSIONS Even when broad criteria are used to define current CRC screening status , a substantial proportion of the age-eligible population remains underscreened . Obtaining regular preventive care and receiving a physician 's recommendation for screening appear to be potent facilitators of screening that should be considered in design ing promotional efforts CONTEXT A family history of colorectal cancer in a first-degree relative increases the risk of developing colorectal cancer . However , the influence of family history on cancer recurrence and survival among patients with established disease remains uncertain . OBJECTIVE To examine the association of family history of colorectal cancer with cancer recurrence and survival of patients with colon cancer . DESIGN , SETTING , AND PARTICIPANTS Prospect i ve observational study of 1087 patients with stage III colon cancer enrolled in a r and omized adjuvant chemotherapy trial ( CALGB 89803 ) between 
    Output:
    
The prevalence of family history may be lower than the commonly cited 10 % , and confirms evidence for increasing levels of risk associated with increasing family-history burden .
There is evidence for higher prevalence of adenomas and of multiple adenomas in people with family history of CRC but no evidence for differential adenoma location or adenoma progression by family history .
Limited data regarding the natural history of CRC by family history suggest a differential age or stage at cancer diagnosis and mixed evidence with respect to tumor location .
Adherence to recommended colonoscopy screening  was higher in people with a family history of CRC .