***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 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: Background Exercise is a modifiable factor that is inversely related to risk for breast cancer .  To determine if physical activity has a preventative effect on development of premalignant breast lesions , we examined the association between exercise and the incidence of proliferative benign breast disease . Methods In 1997 , the Nurses ’ Health Study II cohort reported levels of physical activity during adolescence and adulthood using a vali date d recall instrument . We followed 40,318 participants free from benign breast disease ( BBD ) or cancer prospect ively for four years and confirmed 232 proliferative benign breast lesions by central ized pathology review . Cox proportional hazards models estimated the age-adjusted and multivariable-adjusted relative risks for physical activity and proliferative benign breast disease . Results We observed a significant inverse association for walking and incidence of BBD , risk was reduced by 9 % per hour of walking ( 95 % CI 0 % to 17 % ) , ( p trend = 0.05 ) . Despite a small number of cases , risk of columnar cell lesions also suggested an inverse association with strenuous activity ( RR for 4 or more hours of strenuous activity per week = 0.62 ; 0.31–1.22 compared to < 1 h per week ) . Conclusions This study suggests that exercise may be inversely associated with the risk of developing proliferative benign breast disease , one of the earliest steps in the development of breast cancer BACKGROUND The risk of invasive breast cancer associated with benign breast disease ( BBD ) other than atypical hyperplasia and in situ breast cancer , especially with nonproliferative diagnosis , has not been explored extensively . This report evaluates the risk of breast cancer associated with this lower-category BBD ( LC-BBD ) . METHODS 11 307 women without prior history of atypical hyperplasia or in situ breast cancer at r and omization ( 1992 - 1997 ) were identified from the cohort of the National Surgical Adjuvant Breast and Bowel Project 's Breast Cancer Prevention Trial . Pathologic findings from breast biopsy reports through August 2002 were review ed , and Cox proportional hazards models were used to determine the relative risks ( RRs ) of breast cancer with 95 % confidence intervals ( CIs ) . The relative risks of breast cancer for LC-BBD were adjusted for treatment and for breast cancer risk as determined by the modified Gail model . RESULTS Of the 11 307 women , 1376 had LC-BBD , of whom 47 developed breast cancer , and of the 9931 women without LC-BBD , 291 developed breast cancer .  The RR of breast cancer for women with LC-BBD relative to women without LC-BBD was 1.60 ( 95 % CI = 1.17 to 2.19 ) . Among women 50 years of age and older , the RR of breast cancer for those with LC-BBD was 1.95 ( 95 % CI = 1.29 to 2.93 ) . After adjustment for treatment and breast cancer risk , the RR of breast cancer for women with LC-BBD was 1.41 ( 95 % CI = 1.03 to 1.94 ) . CONCLUSIONS Women with LC-BBD had a statistically significant increased risk of breast cancer . The elevation of breast cancer risk was especially evident in women 50 years of age and older . Furthermore , this risk was independent of that associated with key epidemiologic breast cancer risk factors Specific histologic types of benign breast disease ( BBD ) may increase  breast cancer  risk . The authors analyzed data from a population ‐based , case‐control study of women aged 20 to 54 with newly diagnosed breast cancer and control subjects r and omly selected from the general population . A panel of pathologists classified the histologic findings of biopsy slides for 433 women with breast cancer and 261 control subjects , all of whom had a history of biopsy for BBD , as to the presence of epithelial hyperplasia , atypia , and other histologic features . When compared with women who had never had a breast biopsy , women with BBD without hyperplasia had an odds ratio of 1.5 ( 95 % confidence limits [ CL ] 1.3 to 1.9 ) , women with hyperplasia without atypia had an odds ratio of 1.8 ( CL = 1.3 , 2.4 ) , and women with hyperplasia and atypia had an odds ratio of 2.6 ( CL = 1.6 , 4.1 ) . Fibroadenoma was an independent risk factor for breast cancer ( odds ratio = 1.7 ; CL = 1.1 , 2.5 ) . These findings suggest that women with BBD with epithelial hyperplasia either with or without atypia and women with fibroadenoma should be monitored carefully because of their elevated risk for breast cancer . Cancer 1992 ; 69:1408‐1414 Objective We examined the association between adolescent fiber intake and proliferative BBD , a marker of increased breast cancer risk , in the Nurses ’ Health Study II . Methods Among 29,480 women who completed a high school diet question naire in 1998 , 682 proliferative BBD cases were identified and confirmed by central ized pathology review between 1991 and 2001 . Multivariate-adjusted Cox proportional hazards regression was used to estimate hazard ratios ( HRs ) and 95 % confidence intervals ( CIs ) . Results Women in the highest quintile of adolescent fiber intake had a 25 % lower risk of proliferative BBD ( multivariate HR ( 95 % CI ) : 0.75 ( 0.59 , 0.96 ) , p-trend = 0.01 ) than women in the lowest quintile . High school intake of nuts was also related to significantly reduced BBD risk . Women consuming ≥2 servings of nuts/week had a 36 % lower risk ( multivariate HR ( 95 % CI ) : 0.64 ( 0.48 , 0.85 ) , p-trend < 0.01 ) than women consuming < 1 serving/month . Results were essentially the same when the analysis was restricted to prospect i ve cases ( n = 142 ) diagnosed after return of the high school diet question naire . Conclusions These findings support the hypothesis that dietary intake of fiber and nuts during adolescence influences subsequent risk of breast disease and may suggest a viable means for breast cancer prevention OBJECTIVE : To investigate prospect ively , using alcoholic beverage consumption data collected in real time , the association between adolescent drinking and risk of  biopsy-confirmed benign breast disease ( BBD ) in young women . PARTICIPANTS AND METHODS : The Growing Up Today Study is a prospect i ve cohort study of US girls , aged 9 to 15 years at baseline , with annual question naires from 1996 through 2001 , followed by question naires in 2003 , 2005 , and 2007 . On the 2003 survey , the participants ( then aged 16–23 years ) provided information about their alcoholic beverage consumption in the previous year . On the 2005 and 2007 surveys , a total of 6899 women ( aged 18–27 years ) reported whether a health care provider had ever diagnosed them with BBD ( n = 147 cases ) and whether it was confirmed by biopsy ( n = 67 cases ) ; 6752 women reported never being diagnosed with BBD . RESULTS : Adjusted for age and BMI , quantity of alcohol consumed was associated with increased risk of biopsy-confirmed BBD ( odds ratio : 1.50 per drink per day [ 95 % confidence interval : 1.19–1.90 ] ) . Girls who typically drank 6 or 7 days/week were at higher risk ( odds ratio : 5.50 [ 95 % confidence interval : 1.23–24.53 ] ) compared with those who never drank or who drank less than once per week . CONCLUSIONS : Higher amounts consumed , and more frequent consumption , of alcoholic beverages in adolescence may increase the occurrence of BBD in young women . Advising teenagers to avoid alcoholic beverages , along with smoking and sun exposure , may reduce cancer incidence in adulthood Background Data from the Shanghai Breast Cancer Study were analyzed to evaluate the relationship between benign breast disease ( BBD ) and breast cancer among Chinese women with a self-report of physician-diagnosed BBD . Methods Study participants consisted of 3,452 breast cancer cases and 3,474 population controls recruited by the Shanghai Breast Cancer Study .  In-person interviews were conducted to collect information on demographics and suspected risk factors for breast cancer , including a detailed history of BBD . Unconditional logistic regression was used to derive adjusted odds ratios ( ORadj ) and 95 % confidence intervals ( CI ) for the association between self-reported BBD and breast cancer . Results Women with breast cancer were significantly more likely to have a self-reported history of BBD including lobular proliferation ( ORadj = 1.6 ; 95 % CI 1.4–1.8 ) , fibroadenoma ( ORadj = 1.9 ; 95 % CI 1.6–2.3 ) , and other BBD ( ORadj = 1.6 ; 95 % CI 1.3–2.1 ) . Breast cancer risk was lower for surgically treated fibroadenoma as compared to non-surgically treated and higher for other BBDs that were surgically treated versus non-surgically treated . Conclusions Our results suggest that personal history of BBD is associated with an increased risk of future breast cancer among women in China . Surgical intervention for fibroadenoma may reduce the risk In adult women with retrospective data , childhood adiposity , pubertal growth and development were associated with benign breast disease ( BBD ) and /or breast cancer . The authors prospect ively evaluated these childhood/adolescent characteristics and BBD risk 
    Output:
    
This meta- analysis demonstrates that proliferative benign breast disease with or without atypia is associated with a significant increase in risk of developing breast cancer .