Prognostic Value of FDG-PET in patients with oropharyngeal carcinoma treated with concurrent chemoradiotherapy

Volumetric parameters derived from FLT-PET performed at completion of treatment predict efficacy of Carbon-ion Radiotherapy in patients with locally recurrent Nasopharyngeal Carcinoma

The purpose of this study was to investigate the role of 3'-deoxy-3'-[¹⁸F]fluorothymidine (FLT)-PET for predicting the outcome of patients with locally recurrent nasopharyngeal carcinoma (LR-NPC) treated by carbon-ion radiotherapy (CIRT). Patients received FLT-PET/CT scan one-week prior to or after completion of CIRT were enrolled in the study. All patients were from prospective trials or treated using a standardized protocol. Time-dependent receiver operator characteristics (ROC) were used to determine the optimal cutoff values for FLT-PET parameters. Univariable and multivariable analyses of local progression-free survival (LPFS) were performed using Cox regression, to examine the prognostic value of FLT-PET parameters, including SUV_max, metabolic tumor volume (MTV) and total lesion thymidine (TLT). A total of 41 patients were enrolled. Elevated MTV and TLT were significantly associated with worse LPFS, in both univariable and multivariable analyses. ROC analysis revealed that both an MTV value higher than 8.6 and a TLT value higher than 14.9 were predictive of increased risk of developing local recurrence, the adjusted HRs were 5.59 (p=0.009) and 7.76 (p=0.002), respectively. In conclusion, FLT-PET was found to be a promising prognostic tool for LR-NPC patients and might play a role in the treatment guidance.

Assessing Novel Drugs and Radiation Technology in the Chemoradiation of Oropharyngeal Cancer

Integrating immunotherapy, proton therapy and biological dose escalation into the definitive chemoradiation of oropharyngeal cancer poses several challenges. Reliable and reproducible data must be obtained in a timely fashion. However, despite recent international radiotherapy contouring guidelines, controversy persists as to the applicability of such guidelines to all cases. Similarly, a lack of consensus exists concerning both the definition of the organ at risk for oral mucositis and the most appropriate endpoint to measure for this critical toxicity. Finally, the correlation between early markers of efficacy such as complete response on PET CT following treatment and subsequent survival needs elucidation for biological subsets of oropharyngeal cancer.

Investigation of radiomic signatures for local recurrence using primary tumor texture analysis in oropharyngeal head and neck cancer patients

Radiomics is one such "big data" approach that applies advanced image refining/data characterization algorithms to generate imaging features that can quantitatively classify tumor phenotypes in a non-invasive manner. We hypothesize that certain textural features of oropharyngeal cancer (OPC) primary tumors will have statistically significant correlations to patient outcomes such as local control. Patients from an IRB-approved database dispositioned to (chemo)radiotherapy for locally advanced OPC were included in this retrospective series. Pretreatment contrast CT scans were extracted and radiomics-based analysis of gross tumor volume of the primary disease (GTVp) were performed using imaging biomarker explorer (IBEX) software that runs in Matlab platform. Data set was randomly divided into a training dataset and test and tuning holdback dataset. Machine learning methods were applied to yield a radiomic signature consisting of features with minimal overlap and maximum prognostic significance. The radiomic signature was adapted to discriminate patients, in concordance with other key clinical prognosticators. 465 patients were available for analysis. A signature composed of 2 radiomic features from pre-therapy imaging was derived, based on the Intensity Direct and Neighbor Intensity Difference methods. Analysis of resultant groupings showed robust discrimination of recurrence probability and Kaplan-Meier-estimated local control rate (LCR) differences between "favorable" and "unfavorable" clusters were noted.

Post-treatment 18F-FDG-PET/CT versus contrast-enhanced CT in patients with oropharyngeal squamous cell carcinoma: comparative effectiveness study

OBJECTIVE

To compare the accuracy of same-day therapy-assessment PET/computed tomography (PET/CT) and conventional contrast-enhanced computed tomography (CECT) in patients with oropharyngeal squamous cell carcinoma (OPSCC).

METHODS

A total of 110 (95 men and 15 women; mean age 59 years) patients with biopsy-proven OPSCC were evaluated with same-day PET/CT and CECT pair scans as part of follow-up therapy assessment. Scans were performed within 6 months after the completion of primary treatment (median time: 3.1 months; range: 0.5-6 months). PET/CT and CECT scans were reviewed retrospectively for residual primary site disease, and right and left cervical lymph node involvement. Histopathology or 6 month clinical/imaging follow-up were used as the gold standard. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy were calculated for the primary site and cervical nodal disease.

RESULTS

Of 110 OPSCC patients, 90.9% were human papilloma virus positive, 80.8% were stage 4, and 76.4% received chemoradiation as the primary treatment. The sensitivity, specificity, PPV, NPV, and accuracy of PET/CT and CECT were similar in the evaluation of the primary cancer site (PET/CT: 75.0, 91.5, 25.0, 99.0, and 90.9, respectively, versus CECT: 75.0, 90.6, 23.1, 99.0, and 90.0, respectively). In evaluating cervical lymph node involvement, PET/CT appeared to have higher accuracy (96.8 vs. 81.7%), specificity (97.7 vs. 81.7%), and PPV (45.8 vs. 16.5%), comparable NPV (99.4% for both), and lower sensitivity (65 vs. 75%) compared with same-day CECT.

CONCLUSION

Same-day PET/CT and CECT scans had comparable accuracy in the evaluation of primary tumor sites after completion of therapy in patients with OPSCC. PET/CT showed higher accuracy in the evaluation of cervical lymph node involvement.

Improving imaging diagnosis of persistent nodal metastases after definitive therapy for oropharyngeal carcinoma: specific signs for CT and best performance of combined criteria

BACKGROUND AND PURPOSE

Criteria for detection of persistent nodal metastases in treated oropharyngeal tumors are sensitive but nonspecific, leading to unnecessary nodal dissections. Developing specific imaging criteria for persistent nodal metastases could improve diagnosis while decreasing patient morbidity.

MATERIALS AND METHODS

Patients with oropharyngeal squamous cell carcinoma with nodal metastases treated by definitive radiation therapy and subsequent nodal dissection were retrospectively evaluated. One hundred thirty-eight patients had pre- and posttherapy contrast-enhanced CTs evaluated by radiologists blinded to the status of pathologically proved hemineck persistent nodal metastases. Composite scoring criteria for CT, combined from individual parameters, were compared with radiologists' opinions, previous multiparameter criteria, and outcome data.

RESULTS

New low-attenuation areas and a lack of size change (<20% cross sectional area) were both highly specific for persistent nodal metastases (99%; P = .0004). Extranodal disease on pretherapy imaging was moderately specific (86%; P = .001). The CSC correctly placed 29 patients in a low-risk category compared with 14 by previously reported criteria and radiologist reports. With good second-rater reliability, the CSC cutoff values stratified patients at highest risk of persistent nodal metastases, thereby improving specificity while maintaining sensitivity.

CONCLUSIONS

Comparing pre- and posttherapy examinations improves specificity by discriminating focal findings and size change compared with a single time point. The CSC can categorize the risk of persistent nodal metastases more accurately than previous CT methods. This finding has the potential to improve resource use and reduce surgical morbidity.

Diagnostic performance of post-treatment FDG PET or FDG PET/CT imaging in head and neck cancer: a systematic review and meta-analysis

PURPOSE

Our objective was to conduct a systematic review and meta-analysis of studies assessing the diagnostic performance of (18)F-fluorodeoxyglucose positron emission tomography (FDG PET) with or without computed tomography (CT) in post-treatment response assessment and/or surveillance imaging of head and neck squamous cell carcinoma (HNSCC).

METHODS

A systematic search of the indexed medical literature was done using appropriate keywords to identify relevant studies. Metrics of diagnostic test accuracy, viz. sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) were extracted from individual studies and combined using a random effects model to yield weighted mean pooled estimates with 95% confidence intervals (95% CI). The impact of timing of post-treatment scan, study quality and advancements in PET technology was explored through meta-regression.

RESULTS

A total of 51 studies involving 2,335 patients were included in the meta-analysis. The weighted mean (95% CI) pooled sensitivity, specificity, PPV and NPV of post-treatment FDG PET(CT) for the primary site was 79.9% (73.7-85.2%), 87.5% (85.2-89.5%), 58.6% (52.6-64.5%) and 95.1% (93.5-96.5%), respectively. Similar estimates for the neck were 72.7% (66.6-78.2%), 87.6% (85.7-89.3%), 52.1% (46.6-57.6%) and 94.5% (93.1-95.7%), respectively. Scans done ≥ 12 weeks after completion of definitive therapy had moderately higher diagnostic accuracy on meta-regression analysis using time as a covariate.

CONCLUSION

The overall diagnostic performance of post-treatment FDG PET(CT) for response assessment and surveillance imaging of HNSCC is good, but its PPV is somewhat suboptimal. Its NPV remains exceptionally high and a negative post-treatment scan is highly suggestive of absence of viable disease that can guide therapeutic decision-making. Timing of post-treatment imaging has a significant, though moderate impact on diagnostic accuracy.

PET for Therapeutic Response Monitoring in Oncology

After diagnosis and staging of cancer, the most important process in modern oncology is assessment of therapeutic response. Timely identification of patients with poor response may allow introduction of alternative therapies, sparing patients the toxicity of ineffective treatments, reducing health care cost, and potentially delivering better outcomes. Metabolic imaging using PET is increasingly recognized as providing earlier and more robust assessment than conventional imaging. There are now ample clinical data indicating that PET metabolic response should be strongly considered for inclusion in evaluation of clinical response in individual high-risk malignancies to both direct the care of individual patients and to guide application of new therapies in particular cancer populations.