***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: CONTEXT The effects of continuous combined hormone therapy on gynecologic cancers have not been investigated previously in a r and omized trial setting . OBJECTIVE To determine the possible associations of estrogen plus progestin on gynecologic cancers and related diagnostic procedures . DESIGN , SETTING , AND PARTICIPANTS R and omized , double-blind , placebo-controlled trial of 16 608 postmenopausal women , who had not had a hysterectomy at baseline and who had been recruited from 40 US clinical centers between September 1993 and October 1998 ( average follow-up , 5.6 years ) . INTERVENTION One tablet per day containing 0.625 mg of conjugated equine estrogens plus 2.5 mg of medroxyprogesterone acetate ( n = 8506 ) or placebo ( n = 8102 ) . MAIN OUTCOME MEASURE Incident invasive cancer of the ovary and endometrium . RESULTS In 5.6 years of follow-up , there were 32 cases of invasive ovarian cancer , 58 cases of endometrial cancer , 1 case of nonendometrial uterine cancer , 13 cases of cervical cancer , and 7 cases of other gynecologic cancers . The hazard ratio ( HR ) for invasive ovarian cancer in women assigned to estrogen plus progestin compared with placebo was 1.58 ( 95 % confidence interval [ CI ] , 0.77 - 3.24 ) . The HR for endometrial cancer was 0.81 ( 95 % CI , 0.48 - 1.36 ) . No appreciable differences were found in the distributions of tumor histology , stage , or grade for either cancer site . The incidence of other gynecologic cancers was low and did not differ by r and omization assignment . More women taking estrogen plus progestin required endometrial biopsies ( 33 % vs 6 % ; P<.001 ) . CONCLUSIONS This r and omized trial suggests that continuous combined estrogen plus progestin therapy may increase the risk of ovarian cancer while producing endometrial cancer rates similar to placebo . The increased burden of endometrial biopsies required to assess vaginal bleeding further limits the acceptability of this regimen . These data provide additional support for caution in the use of continuous combined hormones OBJECTIVE The purpose of this study was to assess the duration of sonographically detected changes in the endometrium of women with a history of tamoxifen use . METHODS Patients with breast cancer who had a history of tamoxifen use and documented pelvic sonographic studies were identified by means of clinic data bases in both the Section of Gynecological Oncology and the Section of Obstetrical and Gynecological Ultrasound , University of Chicago , between January 1 , 1996 , and March 30 , 2004 . Of the 99 patients who met study criteria , 34 had discontinued tamoxifen use before the sonographic evaluation . Each patient 's age , gravity and parity , weight , ethnicity , duration and dose of drug use , interval from drug discontinuation until sonographic evaluation , and uterine pathologic findings were review ed . Endometrial thickness as assessed by pelvic sonography was examined in relation to duration of tamoxifen use and time from discontinuation of the drug . Statistical analysis was performed with linear regression and mixed effect linear regression models . RESULTS Endometrial thickness increased with increasing duration of tamoxifen use at a rate of 0.75 mm/y . The mean endometrial thickness after approximately 5 years of tamoxifen use was 12 mm ( range , 6 - 21 mm ) . After discontinuation of tamoxifen , endometrial thickness decreased by 1.27 mm/y . CONCLUSIONS Endometrial thickness as measured by pelvic ultrasound examination increases with the duration of tamoxifen use . After discontinuation of the drug , the measured thickness decreases but at a very slow rate PURPOSE : To investigate the effect of switching from adjuvant tamoxifen to anastrozole ( Arimidex ) treatment in postmenopausal women with endocrine-responsive breast cancer and histologically proven tamoxifen-induced benign endometrial pathology . EXPERIMENTAL DESIGN : Two hundred twenty-six postmenopausal women who had received adjuvant tamoxifen 20 mg/d ( > or = 12 months , < or = 48 months ) and developed abnormal vaginal bleeding and /or an asymptomatic endometrial thickness > 10 mm [ measured by transvaginal ultrasound ( TVUS ) ] were subjected to hysteroscopy and dilation and curettage ( D&C ) . Thereafter , 171 patients were r and omized in a phase III study to continue tamoxifen treatment ( n = 88 ) or switch to anastrozole 1 mg/d ( n = 83 ) . Patients were monitored for < or = 42 months using TVUS at 6-monthly intervals . RESULTS : At study entry , there were no significant differences in vaginal bleeding , endometrial thickness , and histologic findings between the two treatment groups . Throughout the treatment period , there was no significant difference in recurrent vaginal bleeding between groups [ anastrozole , 4 of 83 ( 4.8 % ) ; tamoxifen , 9 of 88 ( 10.2 % ) ; P = 0.18 ] . Six months after r and omization , the mean endometrial thickness for patients who switched to anastrozole was significantly reduced compared with those who continued tamoxifen treatment ( P < 0.0001 ) . Significantly fewer anastrozole patients required a repeat hysteroscopy and D&C compared with those on tamoxifen [ 4 of 83 ( 4.8 % ) and 29 of 88 ( 33.0 % ) , respectively ; P < 0.0001 ] . Repeat hysteroscopy and D&C revealed endometrial atrophy in all 4 cases in the anastrozole group and 14 polyps , 8 hyperplasias , and 7 atrophies in the tamoxifen group . CONCLUSIONS : Switching from tamoxifen to anastrozole treatment significantly reduced the need for a second hysteroscopy and D&C due to recurrent vaginal bleeding or thickening of the endometrium in postmenopausal breast cancer patients with tamoxifen-induced endometrial abnormalities BACKGROUND Transvaginal ultrasonography is a noninvasive procedure that may be used to detect endometrial disease . However , its usefulness in screening for asymptomatic disease in postmenopausal women before or during treatment with estrogen or estrogen-progesterone replacement is not known . METHODS We compared the sensitivity and specificity of transvaginal ultrasonography and endometrial biopsy  for the detection of  endometrial disease  in 448 postmenopausal women who received estrogen alone , cyclic or continuous estrogen-progesterone , or placebo for three years . RESULTS Concurrent ultrasonographic and biopsy results were available for 577 examinations in the 448 women , 99 percent of whom were undergoing routine annual follow-up .  Endometrial thickness was less than 5 mm in 45 percent of the examinations , 5 to 10 mm in 41 percent , more than 10 mm in 12 percent , and not measured in 2 percent , and it was higher in the women receiving estrogen alone than in the other groups . Biopsy detected 11 cases of serious disease : 1 case of adenocarcinoma , 2 cases of atypical simple hyperplasia , and 8 cases of complex hyperplasia . Biopsy also detected simple hyperplasia in 20 cases . At a threshold value of 5 mm for endometrial thickness , transvaginal ultrasonography had a positive predictive value of 9 percent for detecting any abnormality , with 90 percent sensitivity , 48 percent specificity , and a negative predictive value of 99 percent . With this threshold , a biopsy would be indicated in more than half the women , only 4 percent of whom had serious disease . CONCLUSIONS Transvaginal ultrasonography has a poor positive predictive value but a high negative predictive value for detecting serious endometrial disease in asymptomatic postmenopausal women The aim of this study was to assess endometrial thickness using transvaginal sonography in a representative sample of postmenopausal women and to evaluate whether the technique can be used for screening of endometrial cancer . A r and om sample ( n = 1000 ) of the total population of women aged 45 - 80 years resident in the city of Göteborg in 1993 was invited to attend for transvaginal sonography .  The only exclusion criterion was hysterectomy . Transvaginal sonography was performed in 827 women . An endometrium of < or = 4 mm was not investigated further . Women with an endometrium of 5 - 7 mm and non-measurable cases were re-assessed 1 year later , and women with an endometrial thickness of > or = 8 mm were investigated directly with hysteroscopy and /or dilatation and curettage .  A total of 559 women were postmenopausal and 183 were taking some form of hormonal substitution ( 33 % ) . One case of endometrial cancer ( endometrial thickness 19 mm ) , 23 cases of polyps without atypia ( endometrial thickness 8 - 18 mm ) and no cases of endometrial hyperplasia were diagnosed . Endometrial thicknesses were as follows ( mean + /- SEM ; respectively grouped as < or = 4 mm , 5 - 7 mm and > or = 8 mm ) : total population of postmenopausal women ( 3.4 + /- 0.1 mm , 82 % , 13 % and 6 % ) ; postmenopausal women without estrogens ( 3.0 + /- 0.1 mm , 90 % , 7 % and 3 % ) ; postmenopausal women on medium-potency estrogens + gestagen ( 5.1 + /- 0.3 mm , 49 % , 40 % and 11 % ) and women with low-potency estrogens only ( 3.6 + /- 0.3 mm , 85 % , 6 % and 9 % ) . The prevalence of endometrial cancer was 0.2 % and for benign polyps 3.2 % in this representative sample of postmenopausal women . Our results do not support generalized endometrial screening with transvaginal sonography OBJECTIVE In clinical setting s , transvaginal ultrasound has been used to evaluate abnormal vaginal bleeding . Because the endometrium responds to estrogens , endometrial thickness may constitute a biomarker of estrogen status in postmenopausal women . This study aim ed to vali date the transvaginal ultrasonographic measurement of  endometrial thickness  as an estrogen biomarker in asymptomatic , postmenopausal women by demonstrating an association between endometrial thickness and risk factors known to be associated with estrogen exposure . METHOD Endometrial thickness was measured in 1,271 women ages 55 to 74 years who underwent transvaginal ultrasound screening as part of the Prostate , Lung , Colorectal and Ovarian Cancer Screening Trial . A question naire , completed before screening , provided risk factor information , including reproductive and hormone use histories . RESULTS Endometrial thickness measurements ranged from 1 to 32 mm ( median 3.0 mm ) . The frequencies of thicker endometrium ( > or = 3.0 mm ) , according to body mass index ( BMI ) quartile , were 55.2 % , 66.1 % , 69.7 % , and 76.7 % ( P < 0.0001 ) . The frequencies of thicker endometrium were 57.8 % , 58.3 % , and 82.6 % among never users , ex-users , and current users of hormone replacement therapy ( HRT ) , respectively ( P < 0.0001 ) . Other factors associated with thicker endometrium included age , marital status , history of uterine fibroids , years since menopause , and history of hypertension . Statistically significant associations were not seen in analyses limited to current HRT users ( n = 461 ) . In multiple variable analysis ( R2 = 0.08 ) , current HRT use ( P < 0.0001 ) and higher BMI ( P < 0.0001 ) were independently associated with thicker endometrium . CONCLUSION In postmenopausal women , factors reflecting exogenous ( current HRT use ) and endogenous ( BMI ) estrogen exposure were associated with increased endometrial thickness as measured during screening transvaginal ultrasound . Practical limitations related to screening transvaginal ultrasound include measurement variability , lack of information regarding type or dose of HRT , and problems of differentiating true endometrial thickening from unrecognized endometrial polyps or fluid accumulations . Constrained by these limitations , these results partially vali date a transvaginal ultrasound measurement of endometrial thickness as a potential biomarker related to estrogen status Few data are available regarding endometrial histologic features in asymptomatic perimenopausal and postmenopausal women . This study encompasses  endometrial biopsy specimens obtained from 801 such women before enrollment in a multicenter study of estrogen-progestin replacement .  One endometrial cancer was found ( 0.13 % ) ; four additional biopsy specimens showed atypia ( total 0.63 % ) . The endometrium was atrophic in 373 ( 46.9 % ) , proliferative in 133 ( 16.7 % ) , secretory in 54 ( 6.8 % ) , and hyperplastic in 41 ( 5.2 % ) . Insu 
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BENEFITS , HARMS , AND COSTS It is anticipated that the adoption of these recommendations would save postmenopausal women unnecessary anxiety , pain , and risk of procedural complication .
It is also expected to decrease the cost to the health system by eliminating unnecessary interventions