Assessment of tumor response to chemoradiotherapy and predicting prognosis in patients with head and neck squamous cell carcinoma by PERCIST

Criterios PERCIST, Hopkins y parámetros metabólicos de la PET/TC como factores pronósticos en el cáncer escamoso de cabeza y cuello

AIM

To assess the clinical utility of PERCIST and Hopkins criteria and changes in [¹⁸F]FDG PET/CT quantitative parameters as prognostic factors for progression-free survival (PFS) and cancer-specific survival (CSS) in patients with head and neck squamous cell carcinoma treated by chemoradiotherapy.

MATERIAL AND METHODS

Forty patients (34 men) diagnosed with head and neck squamous cell carcinoma were retrospectively assessed over an interval of 8 years. PERCIST and Hopkins criteria were used to assess response to treatment. Variations in the metabolic parameters maximum SUV (ΔSUVmax), metabolic tumor volume (ΔMTV) and total lesion glycolysis (ΔTLG) between pre- and post-treatment PET/CT studies were also determined. The Cox regression model, ROC curves and the Kaplan-Meier method were used for the analysis of prognostic factors and survival curves.

RESULTS

The mean follow-up was 39.4 months, with 24 progressions and 22 deaths. Both PERCIST and Hopkins criteria and the three metabolic parameters were predictive factors in the univariate analysis and only ΔSUVmax was in the multivariate analysis. Survival analysis showed statistically significant differences in PFS and CSS curves for the five parameters considered.

CONCLUSION

Application of PERCIST and Hopkins criteria as well as ΔSUVmax, ΔMTV and ΔTLG from PET/CT studies proved to be prognostic factors for survival in patients in our setting for treating head and neck cancer. The results may help to personalize treatment.

Imaging for Response Assessment in Cancer Clinical Trials

The use of biomarkers is integral to the routine management of cancer patients, including diagnosis of disease, clinical staging and response to therapeutic intervention. Advanced imaging metrics with computed tomography (CT), magnetic resonance imaging (MRI), and positron emission tomography (PET) are used to assess response during new drug development and in cancer research for predictive metrics of response. Key components and challenges to identifying an appropriate imaging biomarker are selection of integral vs integrated biomarkers, choosing an appropriate endpoint and modality, and standardization of the imaging biomarkers for cooperative and multicenter trials. Imaging biomarkers lean on the original proposed quantified metrics derived from imaging such as tumor size or longest dimension, with the most commonly implemented metrics in clinical trials coming from the Response Evaluation Criteria in Solid Tumors (RECIST) criteria, and then adapted versions such as immune-RECIST (iRECIST) and Positron Emission Tomography Response Criteria in Solid Tumors (PERCIST) for immunotherapy response and PET imaging, respectively. There have been many widely adopted biomarkers in clinical trials derived from MRI including metrics that describe cellularity and vascularity from diffusion-weighted (DW)-MRI apparent diffusion coefficient (ADC) and Dynamic Susceptibility Contrast (DSC) or dynamic contrast enhanced (DCE)-MRI (Ktrans, relative cerebral blood volume (rCBV)), respectively. Furthermore, Fluorodexoyglucose (FDG), fluorothymidine (FLT), and fluoromisonidazole (FMISO)-PET imaging, which describe molecular markers of glucose metabolism, proliferation and hypoxia have been implemented into various cancer types to assess therapeutic response to a wide variety of targeted- and chemotherapies. Recently, there have been many functional and molecular novel imaging biomarkers that are being developed that are rapidly being integrated into clinical trials (with anticipation of being implemented into clinical workflow in the future), such as artificial intelligence (AI) and machine learning computational strategies, antibody and peptide specific molecular imaging, and advanced diffusion MRI. These include prostate-specific membrane antigen (PSMA) and trastuzumab-PET, vascular tumor burden extracted from contrast-enhanced CT, diffusion kurtosis imaging, and CD8 or Granzyme B PET imaging. Further excitement surrounds theranostic procedures such as the combination of 68Ga/111In- and 177Lu-DOTATATE to use integral biomarkers to direct care and personalize therapy. However, there are many challenges in the implementation of imaging biomarkers that remains, including understand the accuracy, repeatability and reproducibility of both acquisition and analysis of these imaging biomarkers. Despite the challenges associated with the biological and technical validation of novel imaging biomarkers, a distinct roadmap has been created that is being implemented into many clinical trials to advance the development and implementation to create specific and sensitive novel imaging biomarkers of therapeutic response to continue to transform medical oncology.

Quality Assessment in FDG-PET/CT Imaging of Head-and-Neck Cancer: One Home Run Is Better Than Two Doubles

2-deoxy-2-[¹⁸F]fluoro-D-glucose (FDG) positron emission tomography (PET)/computed tomography (CT) is indicated in head-and-neck cancer for the initial workup when clinically indicated (e. g., large tumors, clinically positive neck, cervical adenopathy from an unknown primary, etc.), for the assessment of treatment response 12 weeks after completion of (chemo)radiotherapy, and during follow-up when there is suspicion of relapse. The successful implementation of FDG-PET/CT in routine clinical practice requires an in-depth understanding of the recent advances in physics and engineering that have significantly improved the imaging capabilities of PET/CT scanners (e.g., digital silicon photomultipliers, point-spread function modeling, and time-of-flight, and Bayesian penalized likelihood reconstruction). Moreover, a coordinated harmonization effort from professional societies (e.g., EANM) and international bodies (e.g., IAEA) has resulted in the creation of quality assurance frameworks (e.g., QUANUM, EARL, GMP) and guidelines that collectively cover the entire spectrum from tracer production, hardware calibration, patient preparation, and scan acquisition, to image interpretation (e.g., PERCIST, Hopkins criteria). The ultimate goal is to standardize the PET/CT technique and to guarantee accurate and reproducible imaging results for every patient. This review summarizes the recent technical breakthroughs in PET/CT scan design and describes the existing quality assessment frameworks with a focus on applications in head-and-neck cancer. Strict adherence to these harmonization efforts will enable leveraging the full potential of PET/CT and translate the proven benefits of this technique into tangible improvements in outcome for patients with head-and-neck cancer in routine clinical care.

FDG-PET/CT improves detection of residual disease and reduces the need for examination under anaesthesia in oropharyngeal cancer patients treated with (chemo-)radiation

PURPOSE

Early detection of residual disease (RD) after (chemo)radiation for oropharyngeal (OPC) is crucial. Surveillance of neck nodes with FDG-PET/CT has been studied extensively, whereas its value for local RD remains less clear. We aim to evaluate the diagnostic value of post-treatment FDG-PET/CT in detecting local RD and the outcome of patients with local RD.

METHODS

A cohort (n = 352) of consecutively treated OPC patients at our institute between 2010 and 2017 was evaluated. Patients that underwent FDG-PET/CT at 3 months post-treatment (n = 94) were classified as having complete (CMR) or partial metabolic response (PMR). PMR was defined as visually detectable metabolic activity above the background of surrounding normal tissues. Primary endpoint was diagnostic accuracy in detecting local RD.

RESULTS

Local RD was seen in 19/352 patients (5%), all of them were HPV negative. The FDG-PET/CT had a sensitivity of 100% (8/8), specificity 85% (73/86), PPV 38% (8/21), NPV 100% (73/73), and accuracy 86%. Patients with local RD had significantly worse OS at 2 years, compared to those without (10 versus 88%, P < 0.001). In multivariable analysis, local RD remained a significant predictive factor for death with a hazard ratio of 11.9 (95% CI 5.8-24.3). The number of patients that underwent PET/CT increased over time (P < 0.001), whereas the number of patients that underwent EUA declined (P = 0.072).

CONCLUSION

FDG-PET/CT has excellent performance for the detection of RD, with the sensitivity and negative predictive value approaching 100%. Due to these excellent results is examination under anaesthesia today in the vast majority of the PET-negative cases not necessary anymore.