***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 Fast and accurate staging is essential for choosing treatment for non-small-cell lung cancer ( NSCLC ) . The purpose of this r and omized study was to evaluate the clinical effect of combined positron-emission tomography and computed tomography ( PET-CT ) on preoperative staging of NSCLC . METHODS We r and omly assigned patients who were referred for preoperative staging of NSCLC to either conventional staging plus PET-CT or conventional staging alone .  Patients were followed until death or for at least 12 months . The primary end point was the number of futile thoracotomies , defined as any one of the following : a thoracotomy with the finding of pathologically confirmed mediastinal lymph-node involvement ( stage IIIA [ N2 ] ) , stage IIIB or stage IV disease , or a benign lung lesion ; an exploratory thoracotomy ; or a thoracotomy in a patient who had recurrent disease or death from any cause within 1 year after r and omization . RESULTS From January 2002 through February 2007 , we r and omly assigned 98 patients to the PET-CT group and 91 to the conventional-staging group . Mediastinoscopy was performed in 94 % of the patients . After PET-CT , 38 patients were classified as having inoperable NSCLC , and after conventional staging , 18 patients were classified thus . Sixty patients in the PET-CT group and 73 in the  conventional-staging group underwent thoracotomy ( P=0.004 ) . Among these thoracotomies , 21 in the PET-CT group and 38 in the conventional-staging group were futile ( P=0.05 ) . The number of justified thoracotomies and survival were similar in the two groups . CONCLUSIONS The use of PET-CT for preoperative staging of NSCLC reduced both the total number of thoracotomies and the number of futile thoracotomies but did not affect overall mortality . ( Clinical Trials.gov number , NCT00867412 . Risk-adapted lymphoma treatment requires early and accurate assessment of prognosis . This investigation prospect ively assessed the value of positron emission tomography with 2-[18F]fluoro-2-deoxy-D-glucose ( FDG-PET ) after two cycles of chemotherapy for prediction of progression-free survival ( PFS ) and overall survival ( OS ) in Hodgkin lymphoma ( HL ) . Seventy-seven consecutive , newly diagnosed patients underwent FDG-PET  at staging , after two and four cycles of chemotherapy , and after completion of chemotherapy . Median follow-up was 23 months . After two cycles of chemotherapy , 61 patients had negative FDG-PET scans and 16 patients had positive scans . Eleven of 16 FDG-PET-positive patients progressed and 2 died . Three of 61 FDG-PET-negative patients progressed ; all were alive at latest follow-up . Survival analyses showed strong associations between early FDG-PET after two cycles and PFS ( P < .001 ) and OS ( P < .01 ) . For prediction of PFS , interim FDG-PET was as accurate after two cycles as later during treatment and superior to computerized tomography ( CT ) at all times . In regression analyses , early interim FDG-PET was stronger than established prognostic factors . Other significant prognostic factors were stage and extranodal disease . Early interim FDG-PET is a strong and independent predictor of PFS in HL . A positive early interim FDG-PET is highly predictive of progression in patients with advanced-stage or extranodal disease UNLABELLED Recent advances in the technology of helical multidetector CT allow precise evaluations of nodule hemodynamics . In addition , the efficacy of tissue characterization has improved , and now sensitivity and specificity of > 90 % are achieved . Moreover , the efficacy of PET for the tissue characterization of solitary pulmonary nodules ( SPNs ) has also become of importance . The purpose of this study was to compare the diagnostic accuracy of helical dynamic ( HD ) CT ( HDCT ) and integrated PET/CT for pulmonary nodule characterization . METHODS One hundred nineteen patients with an SPN underwent both  HDCT ( unenhanced scans , followed by series of images at 30 , 60 , 90 , 120 s and at 5 and 15 min after intravenous injection of contrast medium ) and integrated PET/CT . On HDCT , a nodule was regarded as malignant with a net enhancement of > or = 25 Hounsfield units ( HU ) and a washout of 5 - 31 HU . On integrated PET/CT , nodules were considered malignant with a > or = 3.5 maximum st and ardized uptake value and an 18F-FDG uptake greater than that of mediastinal structures . The sensitivity , specificity , and accuracy of the 2 modalities for malignancy were compared using the McNemar test . RESULTS There were 79 malignant and 40 benign nodules . The sensitivity , specificity , and accuracy for malignancy on HDCT were 81 % ( 64/79 nodules ) , 93 % ( 37/40 ) , and 85 % ( 101/119 ) , respectively , whereas those on integrated PET/CT were 96 % ( 76/79 ) , 88 % ( 35/40 ) , and 93 % ( 111/119 ) , respectively ( P = 0.008 , 0.727 , and 0.011 , respectively ) . All malignant nodules were interpreted correctly on either HDCT or PET/CT . CONCLUSION Integrated PET/CT is more sensitive and accurate than HDCT for the malignant nodule characterization ; therefore , PET/CT may be performed as the first-line evaluation tool for SPN characterization . Because HDCT has high specificity and acceptable sensitivity and accuracy , it may be a reasonable alternative for nodule characterization when PET/CT is unavailable Positron emission tomography ( PET ) performed during cancer therapy ( treatment monitoring ) has shown promise for predicting treatment outcome . However , when used for this purpose , PET generally is not considered st and ard care . Under the Medicare ‘ coverage with evidence development ’ policy , PET ( and integrated PET/computed tomography ) became a covered service for treatment monitoring if prospect i ve registry data were collected Interim 2‐[18F]Fluoro‐2‐deoxy‐D‐glucose Positron Emission Tomography performed after two chemotherapy cycles ( PET‐2 ) is the most reliable predictor of treatment outcome in ABVD‐treated Hodgkin Lymphoma ( HL ) patients . We retrospectively analysed the treatment outcome of a therapeutic strategy based on PET‐2 results : positive patients switched to BEACOPP , while negative patients continued with ABVD .  Between January 2006 and December 2007 , 219 newly diagnosed HL patients admitted to nine centres were enrolled ; 54 patients , unfit to receive this treatment were excluded from the analysis .  PET‐2 scans were review ed by a central panel of nuclear medicine experts , according to the Deauville score ( Meignan , 2009 ) . After a median follow up of 34 months ( 12–52 ) the 2‐year failure free survival ( FFS ) and overall survival for the entire cohort of 165 patients were 88 % and 98 % ; the FFS was 65 % for PET‐2 positive and 92 % for PET‐2 negative patients . For 154 patients in which treatment was correctly given according to  PET‐2  review , the 2‐year FFS was 91 % : 62 % for PET‐2 positive and 95 % for PET‐2 negative patients . Conclusions : this strategy , with BEACOPP intensification only in PET‐2 positive patients , showed better results than ABVD‐treated historic controls , sparing BEACOPP toxicity to the majority of patients ( Clinical Trials.gov Identifier NCT00877747 ) BACKGROUND AND OBJECTIVES In order to receive the most appropriate therapy , patients with Hodgkin 's lymphoma ( HL ) must be accurately stratified into different prognostic staging groups . Computed tomography ( CT ) plays a pivotal role in the conventional staging . The aim of the present study was to investigate the value of positron emission tomography using 2-[18F]fluoro-2-deoxy-D-glucose ( FDG-PET ) and combined FDG-PET/CT for the staging of HL patients , and the impact on the choice of treatment . DESIGN AND METHODS Ninety-nine consecutive , prospect ively included patients had FDG-PET and CT in their staging work-up . Sixty-one of the 99 patients had combined FDG-PET/CT .  A st and ard of reference for each nodal region and organ was determined using all available information including scan results , histology and a minimum of one year 's clinical follow-up data . The lack of a satisfactory diagnostic gold st and ard limits the reliability of accuracy calculations . RESULTS FDG-PET would have upstaged 19 % of patients and downstaged 5 % of patients , leading to a different treatment in 9 % of patients . For FDG-PET/CT , the corresponding figures are 17 % , 5 % , and 7 % . In nodal regions , the sensitivity of FDG-PET and FDG-PET/CT seemed higher than that of CT ( 92 % and 92 % vs. 83 % ) . FDG-PET identified more false positive nodal sites than did CT and FDG-PET/CT ( 1.6 % vs 0.7 % and 0.5 % ) . FDG-PET and FDG-PET/CT were highly sensitive for evaluating organs ( 86 % and 73 % ) while CT detected 37 % of involved organs . INTERPRETATION AND CONCLUSIONS FDG-PET and FDG-PET/CT have a substantial potential impact on staging and choice of treatment and the methods tend to upstage rather than downstage patients .  FDG-PET and FDG-PET/CT seem to have a higher diagnostic accuracy than CT in the staging of HL . However , care should be taken so patients with an excellent prognosis and at risk of over-treatment do not receive more intensive treatment because of these staging methods PURPOSE Under Medicare 's Coverage with Evidence Development policy , positron emission tomography (PET)/computed tomography ( CT ) and PET became covered services for previously noncovered cancer indications if prospect i ve registry data were collected . The National Oncologic PET Registry ( NOPR ) was developed to meet these coverage requirements and to assess how PET affects care decisions . METHODS The NOPR collected question naire data from referring physicians on intended patient management before and after PET . After 1 year , the cohort included data from 22,975 studies ( 83.7 % PET/CT ) from 1,178 centers . The numbers of scans performed for diagnosis of suspected cancer ( or unknown primary cancer ) , initial cancer staging , restaging , and suspected cancer recurrence were approximately equal . Prostatic , pancreatic and ovarian cancers represented approximately 30 % of cases . RESULTS If PET data were not available , the most common pre-PET plan would have been other imaging . In these patients , the post-PET strategies changed to watching in 37 % and treatment in 48 % . In patients with planned biopsy before PET  , biopsy was avoided in approximately 70 % . If the pre-PET strategy was treatment , the post-PET strategy involved a major change in type in 8.7 % and goal in 5.6 % . When intended management was classified as either treatment or nontreatment , the post-PET plan was three-fold more likely to lead to treatment than nontreatment ( 28.3 % v 8.2 % ; odds ratio = 3.4 ; 95 % CI , 3.2 to 3.6 ) . Overall , physicians changed their intended management in 36.5 % ( 95 % CI , 35.9 to 37.2 ) of cases after PET . CONCLUSION This large , prospect i ve , nationally representative registry of elderly cancer patients found that physicians often change their intended management on the basis of PET scan results across the full spectrum of its potential uses BACKGROUND Metastatic head and neck squamous cell carcinoma with an unknown primary is an uncommon but important problem . PET/CT , as an adjunct to diagnosis , is potentially useful but has never been studied in a prospect i ve , single-blinded clinical trial . METHODS In all , 20 subjects with cervical metastases from an unknown head and neck primary were enrolled in a prospect i ve clinical trial . A st and ard protocol was used in both clinic and operating room ( OR ) . Study surgeons were blinded to the PET/CT result upon completion of the st and ard work-up . RESULTS PET/CT increased the detection of a primary site from 25 % to 55 % ( 5 vs 11 subjects ) . This difference was statistically and clinical ly significant ( p = .03 , McNemar 's test ) . There was 1 false negative PET/CT scan .  CONCLUSIONS An unknown primary should be diagnosed only after a complete head and neck examination , flexible endoscopy , and CT or MRI . PET/CT performed prior to panendoscopy will increase the diagnostic yield in the unknown head and neck primary population , leading to more targeted , and less morbid , treatment PURPOSE In lymphoma , [(18)F]fluorodeoxyglucose positron emission tomography ( FDG-PET ) is routinely used for initial staging , early evaluation of treatment response , and identification of disease relapse . However , there are no prospect i ve studies investig 
    Output:
    
The evidence suggested usefulness of  PET/CT  in lung , lymphoma , melanoma , head and neck , and colorectal cancers , whereas evidence was sparse in gynaecological cancers .
Conclusion Evidence -based usefulness was reported in five of six selected cancers ; evidence was sparse in the sixth , gynaecological cancers .
Actual use of PET/CT agreed well with recommendations