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Follow up results of a prospective study to evaluate the impact of FDG-PET on CT-based radiotherapy treatment planning for oesophageal cancer.

ABSTRACT: Background:This prospective study aims to determine the impact of PET/CT on radiotherapy planning and outcomes in patients with oesophageal cancer. Methods:All patients underwent PET/CT scanning in the radiotherapy treatment position, and received treatment planned using the PET/CT dataset. GTV was defined separately on PET/CT (GTV-PET) and CT (GTV-CT) datasets. A corresponding PTV was generated for each patient. Volumetric and spatial analysis quantified the proportion of FDG-avid disease not included in CT-based volumes. Clinical data was collected to determine locoregional control and overall survival rates. Results:13 (24.1%) of 57 accrued patients had metastatic disease detected on PET. Median follow up was 4 years. FDG-avid disease would have been excluded from GTV-CT in 29 of 38 patients (76%). In 5 patients, FDG-avid disease would have been completely excluded from the PTV-CT. GTV-CT underestimated the cranial and caudal extent of FDG-avid tumour in 14 (36%) and 10 (26%) patients. 4-Year overall survival and locoregional failure free survival were 37% and 65%. Conclusions:PET/CT altered the delineation of tumour volumes when compared to CT alone, and should be considered standard for treatment planning. Although clinical outcomes were not improved with PET/CT planning, it did allow the use of smaller radiotherapy volumes.

SUBMITTER: Ng SP

PROVIDER: S-EPMC5893524 | biostudies-literature | 2017 Feb

REPOSITORIES: biostudies-literature

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Follow up results of a prospective study to evaluate the impact of FDG-PET on CT-based radiotherapy treatment planning for oesophageal cancer.

Ng Sweet Ping SP Tan Jennifer J Osbourne Glen G Williams Luke L Bressel Mathias A B MAB Hicks Rodney J RJ Lau Eddie W F EWF Chu Julie J Ngan Samuel Y K SYK Leong Trevor T

Clinical and translational radiation oncology 20170201

<h4>Background</h4>This prospective study aims to determine the impact of PET/CT on radiotherapy planning and outcomes in patients with oesophageal cancer.<h4>Methods</h4>All patients underwent PET/CT scanning in the radiotherapy treatment position, and received treatment planned using the PET/CT dataset. GTV was defined separately on PET/CT (GTV-PET) and CT (GTV-CT) datasets. A corresponding PTV was generated for each patient. Volumetric and spatial analysis quantified the proportion of FDG-avi ...[more]

PMID: 29658005

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Project description:This prospective single-institution study examined the impact of positron emission tomography (PET) with the use of 2-[(18)F] fluoro-2-deoxyglucose and computed tomography (CT) scan radiation treatment planning (TP) on target volume definition in lymphoma.118 patients underwent PET/CT TP during June 2007 to May 2009. Gross tumor volume (GTV) was contoured on CT-only and PET/CT studies by radiation oncologists (ROs) and nuclear medicine physicians (NMPs) for 95 patients with positive PET scans. Treatment plans and dose-volume histograms were generated for CT-only and PET/CT for 95 evaluable sites. Paired t test statistics and Pearson correlation coefficients were used for analysis.70 (74%) patients had non-Hodgkin lymphoma, 10 (11%) had Hodgkin lymphoma, 12 (10%) had plasma-cell neoplasm, and 3 (3%) had other hematologic malignancies. Forty-three (45%) presented with relapsed/refractory disease. Forty-five (47%) received no prior chemotherapy. The addition of PET increased GTV as defined by ROs in 38 patients (median, 27%; range, 5%-70%) and decreased GTV in 41 (median, 39.5%; range, 5%-80%). The addition of PET increased GTV as defined by NMPs in 27 patients (median, 26.5%; range, 5%-95%) and decreased GTV in 52 (median, 70%; range, 5%-99%). The intraobserver correlation between CT-GTV and PET-GTV was higher for ROs than for NMPs (0.94, P<.01 vs 0.89, P<.01). On the basis of Bland-Altman plots, the PET-GTVs defined by ROs were larger than those defined by NMPs. On evaluation of clinical TPs, only 4 (4%) patients had inadequate target coverage (D95 <95%) of the PET-GTV defined by NMPs.Significant differences between the RO and NMP volumes were identified when PET was coregistered to CT for radiation planning. Despite this, the PET-GTV defined by ROs and NMPs received acceptable prescription dose in nearly all patients. However, given the potential for a marginal miss, consultation with an experienced PET reader is highly encouraged when PET/CT volumes are delineated, particularly for questionable lesions and to assure complete and accurate target volume coverage.

Project description:BACKGROUND:To identify whether early metabolic responses as determined using 18F-fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET/CT) during radiotherapy (RT) predict outcomes in patients with esophageal cancer. METHODS:Twenty-one patients with esophageal cancer who received pre-treatment 18F-FDG PET/CT (PET1) and inter-fractional 18F-FDG PET/CT (PET2) after 11 fractions of RT (median 23.1?Gy, 2.1?Gy per fraction) were retrospectively reviewed. The region of interest for each calculation was delineated using "PET Edge". We calculated PET parameters including maximum and mean standardized uptake values (SUVmax and SUVmean, respectively), metabolic tumor volume (MTV), and total lesion glycolysis (TLG). The relative changes (%) were calculated using the logarithmically transformed parameter values for the PET1 and PET2 scans. Multivariate analysis of locoregional recurrence and distant failures were performed using Cox regression analysis. After identifying statistically significant PET parameters for discriminating responders from non-responders, receiver operating characteristics curve analyses were used to assess the potentials of the studied PET parameters. RESULTS:After a median follow-up of 13?months, the 1-year overall and progression-free survival rates were 79.0% and 34.4%, respectively. Four patients developed locoregional recurrences (LRRs) and 8 had distant metastases (DMs). The 1-year overall LRR-free rate was 76.9% while the DM-free rate was 60.6%. The relative changes in MTV (?MTV) were significantly associated with LRR (p =?0.03). Conversely, the relative changes in SUVmean (?SUVmean) were associated with the risk of DM (p =?0.02). An ?MTV threshold of 1.14 yielded a sensitivity of 60%, specificity of 94%, and an accuracy of 86% for predicting an LRR. Additionally, a ?SUVmean threshold of a 35% decrease yielded a sensitivity of 67%, specificity of 83%, and accuracy of 76% for the prediction DM. TRIAL REGISTRATION:Retrospectively registered. CONCLUSIONS:Changes in tumor metabolism during RT could be used to predict treatment responses, recurrences, and prognoses in patients with esophageal cancer.

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Dataset Information

Follow up results of a prospective study to evaluate the impact of FDG-PET on CT-based radiotherapy treatment planning for oesophageal cancer.

Publications

Follow up results of a prospective study to evaluate the impact of FDG-PET on CT-based radiotherapy treatment planning for oesophageal cancer.

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