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Assessment of response to neoadjuvant radiochemotherapy with F-18 FLT and F-18 FDG PET/CT in patients with rectal cancer.

ABSTRACT: The comparison of 2-deoxy-2-[18F]fluoro-D-glucose (F-18 FDG) and 3'-deoxy-3'-[18F]fluorothymidine (F-18 FLT) imaging in patients with rectal cancer before and after neoadjuvant radiochemotherapy (RCT) in relation to histopathology and immunohistochemistry obtained from surgery.20 consecutive patients (15 m, 5 f), mean age of 65 ± 10 years were included into this prospective study with a mean follow-up of 4.1 ± 0.8 years.Among histopathological responders (n = 8 out of 20), posttreatment F-18 FLT and F-18 FDG scans were negative in 75 % (n = 6) and 38 % (n = 3), respectively. The mean response index (RI) was 61.0 % ± 14.0 % for F-18 FLT and 58.7 % ± 14.6 % for F-18 FDG imaging. Peritumoral lymphocytic infiltration (CD3 positive cells) was significantly related to posttreatment SUVmax in F-18 FDG but not F-18 FLT studies.A significant decrease of SUVmax in F-18 FDG and F-18 FLT studies could be seen after RCT. Negative posttreatment F-18 FLT studies identified more histopathological responders.

SUBMITTER: Rendl G

PROVIDER: S-EPMC4661213 | biostudies-literature | 2015 Apr

REPOSITORIES: biostudies-literature

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Assessment of response to neoadjuvant radiochemotherapy with F-18 FLT and F-18 FDG PET/CT in patients with rectal cancer.

Rendl Gundula G Rettenbacher Lukas L Holzmannhofer Johannes J Datz Lidwina L Hauser-Kronberger Cornelia C Fastner Gerd G Öfner Dietmar D Sedlmayer Felix F Pirich Christian C

Annals of nuclear medicine 20141211 3

<h4>Objective</h4>The comparison of 2-deoxy-2-[18F]fluoro-D-glucose (F-18 FDG) and 3'-deoxy-3'-[18F]fluorothymidine (F-18 FLT) imaging in patients with rectal cancer before and after neoadjuvant radiochemotherapy (RCT) in relation to histopathology and immunohistochemistry obtained from surgery.<h4>Methods</h4>20 consecutive patients (15 m, 5 f), mean age of 65 ± 10 years were included into this prospective study with a mean follow-up of 4.1 ± 0.8 years.<h4>Results</h4>Among histopathological re ...[more]

PMID: 25503812

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Project description:There is an unmet need for predictive biomarkers of the clinical benefit of antiangiogenic drugs. The aim of the present study was to prospectively evaluate the value of 18F-FDG PET/CT performed during and after preoperative chemoradiotherapy with bevacizumab for the prediction of complete pathologic tumor regression and survival in patients with MRI-defined high-risk locally advanced rectal cancer. Methods: Sixty-one patients treated in a nonrandomized phase II study (BRANCH) with concomitant or sequential (4 d before chemoradiotherapy) administration of bevacizumab with preoperative chemoradiotherapy were included. 18F-FDG PET/CT was performed at baseline, 11 d after the beginning of chemoradiotherapy (early), and before surgery (late). Metabolic changes were compared with pathologic complete tumor regression (TRG1) versus incomplete tumor regression (TRG2-TRG5), progression-free survival, cancer-specific survival, and overall survival. Receiver-operating-characteristic curves were calculated for those 18F-FDG PET/CT parameters that significantly correlated with TRG1. Results: Early total-lesion glycolysis and its percentage change compared with baseline (ΔTLG-early) could discriminate TRG1 from TRG2-TRG5. Only receiver-operating-characteristic analysis of ΔTLG-early showed an area under the curve greater than 0.7 (0.76), with an optimal cutoff at 59.5% (80% sensitivity, 71.4% specificity), for identifying TRG1. Late metabolic assessment could not discriminate between the 2 groups. After a median follow-up of 98 mo (range, 77-132 mo), metabolic responders (ΔTLG-early ≥ 59.5%) demonstrated a significantly higher 10-y progression-free survival (89.3% vs. 63.6%, P = 0.02) and cancer-specific survival (92.9% vs. 72.6%, P = 0.04) than incomplete metabolic responders. Conclusion: Our results suggest that early metabolic response can act as a surrogate marker of the benefit of antiangiogenic therapy. The findings provide further support for the use of early 18F-FDG PET/CT evaluation to predict pathologic response and survival in the preoperative treatment of patients with locally advanced rectal cancer. ΔTLG-early showed the best accuracy in predicting tumor regression and may be particularly useful in guiding treatment-modifying decisions during preoperative chemoradiotherapy based on expected response.

Project description:Diagnosing relapse after radiotherapy for lung cancer is challenging. The specificity of both CT and 18F-FDG PET/CT is low because of radiation-induced changes. 3'-deoxy-3'-18F-fluorothymidine (18F-FLT) PET has previously demonstrated higher specificity for malignancy than 18F-FDG PET. We investigated the value of 18F-FLT PET/CT for diagnosing relapse in irradiated lung cancer. Methods: Patients suspected of relapse of lung cancer after definitive radiotherapy (conventional fractionated radiotherapy [cRT] or stereotactic body radiotherapy [SBRT]) were included. Sensitivity and specificity were analyzed both within the irradiated high-dose volume (HDV) and on a patient basis. Marginal differences and interobserver agreement were assessed. Results: Sixty-three patients who had received radiotherapy in 70 HDVs (34 cRT; 36 SBRT) were included. The specificity of 18F-FLT PET/CT was higher than that of 18F-FDG PET/CT (HDV, 96% [95% CI, 87-100] vs. 71% [95% CI, 57-83] [P = 0.0039]; patient-based, 90% [95% CI, 73-98] vs. 55% [95% CI, 36-74] [P = 0.0020]). The difference in specificity between 18F-FLT PET/CT and 18F-FDG PET/CT was higher after cRT than after SBRT. The sensitivity of 18F-FLT PET/CT was lower than that of 18F-FDG PET/CT (HDV, 69% [95% CI, 41-89] vs. 94% [95% CI, 70-100] [P = 0.1250]; patient-based, 70% [95% CI, 51-84] vs. 94% [95% CI, 80-99] [P = 0.0078]). Adding 18F-FLT PET/CT when 18F-FDG PET/CT was positive or inconclusive improved the diagnostic value compared with 18F-FDG PET/CT alone. In cRT HDVs, the probability of malignancy increased from 67% for 18F-FDG PET/CT alone to 100% when both tracers were positive. Conclusion: 18F-FLT PET/CT adds diagnostic value to 18F-FDG PET/CT in patients with suspected relapse. The diagnostic impact of 18F-FLT PET/CT was highest after cRT. We suggest adding 18F-FLT PET/CT when 18F-FDG PET/CT is inconclusive or positive within the previously irradiated volume to improve diagnostic value in patients for whom histologic confirmation is not easily obtained.

Dataset Information

Assessment of response to neoadjuvant radiochemotherapy with F-18 FLT and F-18 FDG PET/CT in patients with rectal cancer.

Publications

Assessment of response to neoadjuvant radiochemotherapy with F-18 FLT and F-18 FDG PET/CT in patients with rectal cancer.

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