***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 and aims : Specialised intestinal metaplasia and its dysplastic transformation , which precedes cancer in Barrett ’s oesophagus can not be differentiated in st and ard gastroscopy . The aim of this study was to investigate whether laser induced protoporphyrin IX fluorescence permits the detection of specialised intestinal metaplasia and dysplasia during endoscopy and to take biopsy specimens in a guided rather than r and om manner . Methods : In 53 patients with Barrett ’s oesophagus  5-aminolaevulinic acid was sprayed on the mucosa . Approximately 60 to 120 minutes later , biopsy specimens were taken based on point-like measurements of delayed fluorescence intensity ratios of protoporphyrin IX in vivo . Two independent pathologists examined the 596 biopsy specimens taken , 168 of which were selected to be investigated by a third pathologist . Among these specimens only those ( n=141 ) with a consensus diagnosis by at least two pathologists and p53 expression as additional marker were included in the analysis . Results : The median of normalised fluorescence intensity ( ratio of delayed PpIX fluorescence intensity to immediate autofluorescence intensity ) in non-dysplastic specialised intestinal metaplasia ( 0.51 , 68 % CI 0.09 to 1.92 ) and low grade dysplasia ( 1.89 , 68 % CI 0.55 to 3.92 ) differed significantly ( p<0.005 ) . Dysplasia was detected at a rate 2.8-fold higher compared with screening endoscopy despite taking fewer specimens . In addition , three early cancers were detected for the first time . Moreover , this method permitted differentiation of specialised intestinal metaplasia from junctional or gastric-fundic type epithelium ( p<0.013 ) . Conclusions : For the first time it was possible to differentiate low grade dysplasia from non-dysplastic Barrett ’s mucosa during endoscopy based on delayed laser induced fluorescence endoscopy of PpIX . Furthermore , the method helps to detect specialised intestinal metaplasia in short Barrett ’s oesophagus BACKGROUND AND AIMS Photodynamic therapy ( PDT ) is a treatment in which cell damage is achieved by the action of light on a photosensitising agent . We have assessed the potential use of PDT in the ablation of Barrett 's oesophagus . METHODS Thirty six patients with dysplastic Barrett 's oesophagus receiving acid suppression medication with omeprazole were r and omised to receive oral 5-aminolaevulinic acid ( ALA ) 30 mg/kg or placebo , followed four hours later by laser endoscopy . Follow up endoscopy was performed at one , six , 12 , and 24 months . RESULTS Of 18 patients in the ALA group , a response was seen in 16 ( median decrease in area in the treated region 30 % ; range 0–60 % ) . In the placebo group , a decrease in area of 10 % was observed in two patients with no change in 16 ( median 0 % ; range 0–10 % ; treatment vplacebo , p<0.001 ) . No dysplasia was seen in the columnar epithelium within the treatment area of any patient in the PDT group . However , in the placebo group , persistent low grade dysplasia was found in 12 patients ( p<0.001 ) . There were no short or long term major side effects . The effects of treatment were maintained for up to 24 months . CONCLUSIONS This is the first r and omised controlled trial of PDT for Barrett 's oesophagus . It demonstrates that ALA induced PDT can provide safe and effective ablation of low grade dysplastic epithelium Barrett 's oesophagus is a major risk factor for developing oesophageal adenocarcinoma . Ablation by argon plasma coagulation ( APC ) and photodynamic therapy ( PDT ) is currently under investigation for the removal of metaplastic and dysplastic Barrett 's oesophagus . This study examined the effect of ablative therapy on Barrett 's oesophagus at cell-cycle and genetic levels . The premalignant potential of residual or recurring Barrett 's oesophagus was assessed by p53 immunohistochemistry , Ki67-related proliferative capacity , and DNA ploidy status ( ie an abnormal chromosome 1 number ) as measured by interphase in situ hybridization . Twenty-nine patients with Barrett 's oesophagus ( 23 male and 6 female , mean age 58 years , mean length of Barrett 's oesophagus 4 cm ) were treated with APC or PDT .  Intestinal metaplasia without dysplasia was present in 16 patients , low- grade dysplasia in five , and high- grade dysplasia in eight patients . Biopsy sample s were obtained at regular intervals ( mean follow-up 20 months , range 6 - 36 months ) . One month after the first ablation , Barrett 's oesophagus was no longer identified , either endoscopically or histologically , in nine patients ( 32 % ) . At this time point , significant down-grading was achieved for abnormal chromosome 1 numbers ( p = 0.020 ) and Ki67-defined proliferation ( p = 0.002 ) . Patients with residual Barrett 's oesophagus were additionally treated with APC , result ing in the elimination of Barrett 's oesophagus in 76 % of all patients . However , at the last follow-up endoscopy , metaplasia without dysplasia was still present in five patients , and low- and high- grade dysplasia were each present in one patient . An abnormal chromosome 1 number and p53 protein overexpression were detected only in the high- grade dysplastic lesion , but increased proliferation was still present in the majority of these persisting cases . Although endoscopic removal of Barrett 's oesophagus by ablative therapies is possible in the majority of patients , histologically complete elimination can not be achieved in all cases . Persistent Barrett 's oesophagus may still harbour molecular aberrations and must therefore be considered still to be at risk of progression to adenocarcinoma INTRODUCTION Acid suppression therapy and surgical antireflux procedures have not consistently led to regression of Barrett 's epithelium . We reasoned that laser photocoagulation in combination with powerful acid suppression might destroy the metaplastic columnar epithelium and allow the area to be replaced by normal squamous mucosa . PATIENTS AND METHODS Eight patients with endoscopic and histologically proven Barrett 's oesophagus were recruited into the study . Four patients were r and omized to receive omeprazole 40 mg daily and four patients received the same medical therapy plus repeated laser photocoagulation administered at 4 - 6 weekly intervals . Endoscopies were performed on entry and at 6 months . The extent of Barrett 's epithelium was assessed and mapped on to a grid system and histological changes were assessed in blinded manner by a single histopathologist . One new quadrant of Barrett 's segment was irradiated per treatment . RESULTS Laser therapy was well tolerated and no complications occurred . After 6 months , the extent of Barrett 's epithelium was unchanged in both groups . There was no appearance of squamous isl and s either endoscopically or microscopically in areas treated with laser . CONCLUSION Nd-YAG laser is ineffective in ablating Barrett 's epithelium Background : Many modalities have been used to ablate Barrett ’s oesophagus ( BO ) . However , long term results and comparative effectiveness are unknown . Aims : Our aim was to compare the long term efficacy of achieving complete reversal ( endoscopic and histological ) between multipolar electrocoagulation ( MPEC ) and argon plasma coagulation ( APC ) in BO patients and assess factors influencing successful ablation . Methods : Patients with BO , 2–6 cm long , underwent 24 hour pH testing on proton pump inhibitor ( PPI ) therapy . Patients were then r and omised by BO length to undergo ablation with MPEC or APC every 4–8 weeks until endoscopic reversal or maximal of six treatment sessions . Results : Thirty five BO patients have been followed for at least two years following endoscopic ablation , 16 treated with MPEC and 19 with APC . There was complete reversal of BO in 24 patients ( 69 % ) ; 75 % with MPEC and 63 % with APC ( p = 0.49 ) . There was no difference in the number of sessions required in the two groups . There was no difference in age , pH results , BO length , PPI dose , or hiatal hernia size between patients with and without complete reversal . One patient developed an oesophageal stricture but there were no major complications such as bleeding or perforation . Conclusions : In BO patients treated with  MPEC or APC in combination with acid suppression , at long term follow up , complete reversal of BO can be maintained in approximately 70 % of patients , irrespective of the technique . There are no predictors associated with achieving complete reversal of BO . Continued surveillance is still indicated in the post ablative setting . As yet , these techniques are not ready for clinical application ( other than for high grade dysplasia or early oesophageal adenocarcinoma ) and can not be offered outside the research arena BACKGROUND Selective inhibition of cyclooxygenase-2 ( COX-2 ) may be associated with an increased risk of thrombotic events , but only limited long-term data have been available for analysis . We report on the cardiovascular outcomes associated with the use of the selective COX-2 inhibitor rofecoxib in a long-term , multicenter , r and omized , placebo-controlled , double-blind trial design ed to determine the effect of three years of treatment with rofecoxib on the risk of recurrent neoplastic polyps of the large bowel in patients with a history of colorectal adenomas . METHODS A total of 2586 patients with a history of colorectal adenomas underwent r and omization : 1287 were assigned to receive 25 mg of rofecoxib daily , and 1299 to receive placebo . All investigator-reported serious adverse events that represented potential thrombotic cardiovascular events were adjudicated in a blinded fashion by an external committee . RESULTS A total of 46 patients in the rofecoxib group had a confirmed thrombotic event during 3059 patient-years of follow-up ( 1.50 events per 100 patient-years ) , as compared with 26 patients in the placebo group during 3327 patient-years of follow-up ( 0.78 event per 100 patient-years ) ; the corresponding relative risk was 1.92 ( 95 percent confidence interval , 1.19 to 3.11 ; P=0.008 ) . The increased relative risk became apparent after 18 months of treatment ; during the first 18 months , the event rates were similar in the two groups . The results primarily reflect a greater number of myocardial infa rct ions and ischemic cerebrovascular events in the rofecoxib group . There was earlier separation ( at approximately five months ) between groups in the incidence of nonadjudicated investigator-reported congestive heart failure , pulmonary edema , or cardiac failure ( hazard ratio for the comparison of the rofecoxib group with the placebo group , 4.61 ; 95 percent confidence interval , 1.50 to 18.83 ) . Overall and cardiovascular mortality was similar in the two groups . CONCLUSIONS Among patients with a history of colorectal adenomas , the use of rofecoxib was associated with an increased cardiovascular risk Background : Barrett 's esopagus ( BE ) is considered a risk factor for the development of esophageal carcinoma . Recently , partial restoration of squamous mucosa after ablation of BE with endoscopic techniques has been described . Methods : From November 1996 to November 1999 , 23 patients with histologically proven BE have been treated by endoscopic argon plasma coagulation ( APC ) following suppression of gastro-esophageal reflux by laparoscopic fundoplication .  Histological follow-up after completed ablation ranged from 16 to 45 months ( mean , 31.9 months ) . Results : Histologically , complete squamous reepithelialization was observed in 20/23 patients , whereas a regrowth of a mixed squamous and gastric type mucosa was observed in 1 patient . Small isl and s of intestinal metaplasia were observed under the neosquamous epithelium in two patients ( 9 % ) during follow-up . Conclusion : The success rate of APC ablation following laparoscopic antireflux surgery in our series may be as high as 91 % . Nevertheless , small isl and s of intestinal metaplasia under the new squamous epithelium may persist in some patients . In these circumstances , the authors recommend that endoscopic ablation of BE should be confined to controlled clinical trials The guidelines for the diagnosis , surveillance and therapy of Barrett ’s esophagus were originally published by the American College of Gastroenterology in 1998 and up date d in 2002 . These and other guidelines undergo periodic review . Significant advances have occurred in the area of Barrett ’s esophagus over the past four years leading to another revision of the prior guidelines . These advances include the potential use 
    Output:
    
Medical and surgical interventions to reduce symptoms and sequelae of gastro-oesophageal reflux disease ( GORD ) did not induce significant eradication of Barrett 's oesophagus or dysplasia .
Endoscopic therapies ( photodynamic therapy ( PDT with aminolevulinic acid or porfimer sodium ) , argon plasma coagulation ( APC ) and radiofrequency ablation ( RFA ) ) all induced regression of Barrett 's oesophagus and dysplasia .
The variation in photodynamic therapy eradication rates for dysplasia was dependent on the drug , source and dose of light .
Ablative therapies have an increasing role in the management of dysplasia within Barrett 's and current data would favour the use of radiofrequency ablation compared with photodynamic therapy .
Radiofrequency ablation has been shown to yield significantly fewer complications than photodynamic therapy and is very efficacious at eradicating both dysplasia and Barrett 's itself .