Ensuring the right PET scan for the right patient

Bone Metastases Are Measurable: The Role of Whole-Body MRI and Positron Emission Tomography

Metastatic tumor deposits in bone marrow elicit differential bone responses that vary with the type of malignancy. This results in either sclerotic, lytic, or mixed bone lesions, which can change in morphology due to treatment effects and/or secondary bone remodeling. Hence, morphological imaging is regarded unsuitable for response assessment of bone metastases and in the current Response Evaluation Criteria In Solid Tumors 1.1 (RECIST1.1) guideline bone metastases are deemed unmeasurable. Nevertheless, the advent of functional and molecular imaging modalities such as whole-body magnetic resonance imaging (WB-MRI) and positron emission tomography (PET) has improved the ability for follow-up of bone metastases, regardless of their morphology. Both these modalities not only have improved sensitivity for visual detection of bone lesions, but also allow for objective measurements of bone lesion characteristics. WB-MRI provides a global assessment of skeletal metastases and for a one-step "all-organ" approach of metastatic disease. Novel MRI techniques include diffusion-weighted imaging (DWI) targeting highly cellular lesions, dynamic contrast-enhanced MRI (DCE-MRI) for quantitative assessment of bone lesion vascularization, and multiparametric MRI (mpMRI) combining anatomical and functional sequences. Recommendations for a homogenization of MRI image acquisitions and generalizable response criteria have been developed. For PET, many metabolic and molecular radiotracers are available, some targeting tumor characteristics not confined to cancer type (e.g. 18F-FDG) while other targeted radiotracers target specific molecular characteristics, such as prostate specific membrane antigen (PSMA) ligands for prostate cancer. Supporting data on quantitative PET analysis regarding repeatability, reproducibility, and harmonization of PET/CT system performance is available. Bone metastases detected on PET and MRI can be quantitatively assessed using validated methodologies, both on a whole-body and individual lesion basis. Both have the advantage of covering not only bone lesions but visceral and nodal lesions as well. Hybrid imaging, combining PET with MRI, may provide complementary parameters on the morphologic, functional, metabolic and molecular level of bone metastases in one examination. For clinical implementation of measuring bone metastases in response assessment using WB-MRI and PET, current RECIST1.1 guidelines need to be adapted. This review summarizes available data and insights into imaging of bone metastases using MRI and PET.

Prognostic value of primary tumor SUVmax on pre-treatment 18F-FDG PET/CT imaging in patients with stage iii non-small cell lung cancer

OBJECTIVES

Concomitant chemoradiotherapy (CCRT) is widely used in the treatment of patients with stage iii non-small cell lung carcinoma (NSCLC). The early identification of patients with poor prognosis is the premise of personalized treatment for patients. The aim of the study was to evaluate the prognostic value of clinical parameters and primary tumor SUVmax on pre-treatment 18F-FDG PET/CT in patients with stage iii NSCLC.

MATERIAL AND METHODS

Clinical records of 79 stage iii-NSCLC patients with pre-treatment 18F-FDG PET/CT imaging, treated with definitive CCRT were retrospectively reviewed. The clinical endpoints in terms of progression-free survival (PFS) and overall survival (OS) were correlated with the median pre-treatment primary tumor SUVmax. Furthermore, other factors influencing patient outcome were analyzed.

RESULTS

The median age of patients was 58 years (range, 45-71) with 72 (91%) males. Squamous cell carcinoma (73%) was the most common histologic type. Performance status was very good (ECOG 0) in 64.5% of patients. Sixty (79%) patients had died at the time of this analysis. Median OS and PFS were 22.5 and 12.0 months, respectively. Patients were dichotomized according to pre-treatment primary tumor SUVmax≤15.0 vs.>15.0. There was no statistically significant difference for OS and PFS in both arms. Multivariate analysis showed that pre-treatment SUVmax was not a significant predictor of OS (HR 1.099, P=0.726) and PFS (HR 1.022, P=0.941).

CONCLUSIONS

SUVmax with threshold value of 15.0 on the primary tumor before treatment had no prognostic value in our patient group with stage iii NSCLC treated with definitive CCRT.

18F-fluorodeoxyglucose positron emission tomography for predicting tumor response to radiochemotherapy in nasopharyngeal carcinoma

PURPOSE

The aim of this study was to evaluate the value of (18)F-fluorodeoxyglucose (FDG) positron emission tomography (PET) in predicting tumor response to radiochemotherapy in nasopharyngeal carcinoma (NPC).

MATERIALS AND METHODS

From July 2012 to March 2014, 46 NPC patients who had undergone PET scanning before receiving definitive intensity-modulated radiotherapy (IMRT) treatment in our hospital were enrolled. Factors potentially affecting tumor response to treatment were studied by multiple logistic regression analysis.

RESULTS

After radiochemotherapy, 32 patients had a clinical complete response (CR), making the CR rate 69.6%. Multiple logistic regression analysis demonstrated that the maximal standard uptake value (SUV max) of the primary tumor was the only factor related to tumor response (p = 0.001), and that the logistic model had a high positive predictive value (90.6%). The area under the receiver operating characteristic (ROC) curve was 0.809, with a best cutoff threshold at 10.05. Patients with SUV max ≤ 10 had a higher CR rate than those with SUV max > 10 (p < 0.001).

CONCLUSION

The SUV max of the primary tumor before treatment is an independent predictor of tumor response in NPC.

18F-FDG PET or PET-CT to evaluate prognosis for head and neck cancer: a meta-analysis

PURPOSE

The purpose of this meta-analysis was to evaluate the prognostic value of standard uptake value (SUV) from serial Fluorine-18-fluorodeoxyglucose positron emission tomography/computed tomography ((18)F-FDG PET/CT) in patients with head and neck cancer.

METHODS

We searched for articles limited to head and neck cancer, dealt with the impact of SUV on survival and published in English. The endpoints were disease-free survival (DFS), overall survival (OS), and local control (LC). Two reviewers extracted data independently.

RESULTS

Thirty-five studies were identified; of which, 26 studies involving 1,415 patients met the inclusion criteria. Pooled survival data suggested better DFS, OS, and LC in patients with low SUV of pre-treatment, and the odds ratio (OR) was 0.23, 0.24, and 0.27, respectively. Patients having tumors with low SUV of post-treatment also had significantly better DFS (OR = 0.17) and OS (OR = 0.28) than those with high SUV.

CONCLUSIONS

The present meta-analysis showed that (18)F-FDG uptake, as measured by the SUV before treatment and metabolic response after treatment, are valuable for predicting long-term survival in head and neck cancer. High (18)F-FDG uptake may be useful for identifying patients requiring more aggressive treatment.

A systematic review of PET and PET/CT in oncology: a way to personalize cancer treatment in a cost-effective manner?

BACKGROUND

A number of diagnostic tests are required for the detection and management of cancer. Most imaging modalities such as computerized tomography (CT) are anatomical. However, positron emission tomography (PET) is a functional diagnostic imaging technique using compounds labelled with positron-emitting radioisotopes to measure cell metabolism. It has been a useful tool in studying soft tissues such as the brain, cardiovascular system, and cancer. The aim of this systematic review is to critically summarize the health economic evidence of oncologic PET in the literature.

METHODS

Eight electronic databases were searched from 2005 until February 2010 to identify economic evaluation studies not included in previous Health Technology Assessment (HTA) reports. Only full health economic evaluations in English, French, or German were considered for inclusion. Economic evaluations were appraised using published quality criteria for assessing the quality of decision-analytic models. Given the variety of methods used in the health economic evaluations, the economic evidence has been summarized in qualitative form.

RESULTS

From this new search, 14 publications were identified that met the inclusion criteria. All publications were decision-analytic models and evaluated PET using Fluorodeoxyglucose F18 (FDG-PET). Eight publications were cost-effectiveness analyses; six were cost-utility analyses. The studies were from Australia, Belgium, Canada, France, Italy, Taiwan, Japan, the Netherlands, the United Kingdom, and the United States. In the base case analyses of these studies, cost-effectiveness results ranged from dominated to dominant. The methodology of the economic evaluations was of varying quality. Cost-effectiveness was primarily influenced by the cost of PET, the specificity of PET, and the risk of malignancy.

CONCLUSIONS

Owing to improved care and less exposure to ineffective treatments, personalized medicine using PET may be cost-effective. However, the strongest evidence for the cost-effectiveness of PET is still in the staging of non-small cell lung cancer. Management decisions relating to the assessment of treatment response or radiotherapy treatment planning require further research to show the impact of PET on patient management and its cost-effectiveness. Because of the potential for increased patient throughput and the possible greater accuracy, the cost-effectiveness of PET/CT may be superior to that of PET. Only four studies of the cost-effectiveness of PET/CT were found in this review, and this is clearly an area for future research.

[What is the role of FDG-PET in thoracic oncology in 2010?]

18F-Fluorodeoxyglucose-Positron Emission Tomography (FGD-PET) has been considered to have a major impact on the management of lung malignancies since the beginning of this century. Its value has been demonstrated by many publications, meta-analysis and European/American/Japanese recommendations. PET combined with computed tomography has provided useful information regarding the diagnosis and staging of lung cancer and allows for the delivery of adaptive radiotherapy. In its more common uses, PET has been shown to be cost-effective. With the widespread use of new radiotracers, PET will play an increasing role in the evaluation of response to treatment.