Evaluation of response to neoadjuvant chemotherapy for esophageal cancer: PET response criteria in solid tumors versus response evaluation criteria in solid tumors

PET response criteria for solid tumors predict survival at three months after intra-arterial resin-based 90Yttrium radioembolization therapy for unresectable intrahepatic cholangiocarcinoma

PURPOSE

PET Response Criteria for Solid Tumors (PERCIST) were assessed and correlated with survival analysis after resin-based 90Yttrium (90Y) radioembolization therapy for intrahepatic cholangiocarcinoma (ICC).

PATIENTS AND METHODS

Target and overall PERCIST and Response Criteria for Solid Tumors (RECIST) treatment responses were assessed in consecutive patients treated with Y radioembolization for ICC refractory to standard chemotherapy. Significant measurable tumor was defined as 1 cm or greater in diameter and SUVpeak of 2.5 or greater in targeted and nontargeted lesions. The PERCIST defines complete response as resolution of 18F-FDG uptake within measurable lesions, and partial response as 30% reduction in 18F-FDG peak standardized uptake value in measurable lesions. Objective response included partial response and complete response. Survival analysis by Kaplan-Meier and log-rank proportional models was performed using SPSS software version 20.0 (IBM, Armonk, NY), and significance was set at P < 0.05.

RESULTS

Median overall survival (OS) of 9 consecutive patients (56% women; mean age, 58 years) from 90Y therapy was 21.7 months. At 3 months, PERCIST objective response rate of target lesions was 77.7%, and target objective response on PERCIST correlated significantly to prolonged OS (P = 0.022). Overall objective PERCIST response at 3 months had significant correlation with OS (P = 0.011). Probability of death was significantly higher in overall nonresponders by PERCIST (hazard ratio, 12.3). No objective response was seen with RECIST.

CONCLUSIONS

In patients with unresectable ICC refractory to standard chemotherapy, PERCIST at 3 months for assessment of imaging response after 90Y radioembolization therapy predict OS.

State-Of-The-Art and Recent Advances in Quantification for Therapeutic Follow-Up in Oncology Using PET

¹⁸F-fluoro-2-deoxyglucose (¹⁸F-FDG) positron emission tomography (PET) is an important tool in oncology. Its use has greatly progressed from initial diagnosis to staging and patient monitoring. The information derived from ¹⁸F-FDG-PET allowed the development of a wide range of PET quantitative analysis techniques ranging from simple semi-quantitative methods like the standardized uptake value (SUV) to “high order metrics” that require a segmentation step and additional image processing. In this review, these methods are discussed, focusing particularly on the available methodologies that can be used in clinical trials as well as their current applications in international consensus for PET interpretation in lymphoma and solid tumors.

State-of-the-art molecular imaging in esophageal cancer management: implications for diagnosis, prognosis, and treatment

Molecular imaging techniques are increasingly being used in addition to standard imaging methods such as endoscopic ultrasound (EUS) and computed tomography (CT) for many cancers including those of the esophagus. In this review, we will discuss the utility of the most widely used molecular imaging technique, (18)F-fluorodeoxyglucose ((18)F-FDG) positron emission tomography (PET). (18)F-FDG PET has a variety of potential applications ranging from improving staging accuracy at the time of initial diagnosis to assisting in radiation target volume delineation. Furthermore, (18)F-FDG PET can be used to evaluate treatment response after completion of neoadjuvant therapy or potentially during neoadjuvant therapy. Finally, we will also discuss other novel molecular imaging techniques that have potential to further improve cancer care.

Nonsurgical giant cell tumour of the tendon sheath or of the diffuse type: are MRI or 18F-FDG PET/CT able to provide an accurate prediction of long-term outcome?

PURPOSE

To investigate whether MRI (RECIST 1.1, WHO criteria and the volumetric approach) or (18)F-FDG PET/CT (PERCIST 1.0) are able to predict long-term outcome in nonsurgical patients with giant cell tumour of the tendon sheath or of the diffuse type (GCT-TS/DT).

METHODS

Fifteen "nonsurgical" patients with a histological diagnosis of GCT-TS/DT were divided into two groups: symptomatic patients receiving targeted therapy and asymptomatic untreated patients. All 15 patients were evaluated by MRI of whom 10 were treated, and a subgroup of 7 patients were evaluated by PET/CT of whom 4 were treated. Early evolution was assessed according to MRI and PET/CT scans at baseline and during follow-up. Cohen's kappa coefficient was used to evaluate the degree of agreement between PERCIST 1.0, RECIST 1.1, WHO criteria, volumetric approaches and the reference standard (long-term outcome, delay 505 ± 457 days). The response rate in symptomatic patients with GCT-TS/DT receiving targeted therapy was also assessed in a larger population that included additional patients obtained from a review of the literature.

RESULTS

The kappa coefficients for agreement between RECIST/WHO/volumetric criteria and outcome (15 patients) were respectively: 0.35 (p = 0.06), 0.26 (p = 0.17) and 0.26 (p = 0.17). In the PET/CT subgroup (7 patients), PERCIST was in perfect agreement with the late symptomatic evolution (kappa = 1, p < 0.05). In the treated symptomatic group including the additional patients from the literature the response rates to targeted therapies according to late symptomatic assessment, and PERCIST and RECIST criteria were: 65 % (22/34), 77 % (10/13) and 26 % (10/39).

CONCLUSION

(18)F-FDG PET/CT with PERCIST is a promising approach to the prediction of the long-term outcome in GCT-TS/DT and may avoid unnecessary treatments, toxicity and costs. On MRI, WHO and volumetric approaches are not more effective than RECIST using the current thresholds.

Quantitative multimodality imaging in cancer research and therapy

Advances in hardware and software have enabled the realization of clinically feasible, quantitative multimodality imaging of tissue pathophysiology. Earlier efforts relating to multimodality imaging of cancer have focused on the integration of anatomical and functional characteristics, such as PET-CT and single-photon emission CT (SPECT-CT), whereas more-recent advances and applications have involved the integration of multiple quantitative, functional measurements (for example, multiple PET tracers, varied MRI contrast mechanisms, and PET-MRI), thereby providing a more-comprehensive characterization of the tumour phenotype. The enormous amount of complementary quantitative data generated by such studies is beginning to offer unique insights into opportunities to optimize care for individual patients. Although important technical optimization and improved biological interpretation of multimodality imaging findings are needed, this approach can already be applied informatively in clinical trials of cancer therapeutics using existing tools. These concepts are discussed herein.

A semi-automated technique determining the liver standardized uptake value reference for tumor delineation in FDG PET-CT

BACKGROUND

18F-fluorodeoxyglucose (FDG) positron emission tomography (PET)-computed tomography (CT) has been an essential modality in oncology. We propose a semi-automated algorithm to objectively determine liver standardized uptake value (SUV), which is used as a threshold for tumor delineation.

METHODS

A large spherical volume of interest (VOI) was placed manually to roughly enclose the right lobe (RL) of the liver. For each voxel in this VOI, a coefficient of variation of voxel values (CVv) was calculated for neighboring voxels within a radius of d/2. The voxel with the minimum CVv was then selected, where a 30-mm spherical VOI was placed at that voxel in accordance with PERCIST criteria. Two nuclear medicine physicians independently defined 30-mm VOIs manually on 124 studies in 62 patients to generate the standard values, against which the results from the new method were compared.

RESULTS

The semi-automated method was successful in determining the liver SUV that was consistent between the two physicians in all the studies (d = 80 mm). The liver SUV threshold (mean +3 SD within 30-mm VOI) determined by the new semi-automated method (3.12±0.61) was not statistically different from those determined by the manual method (Physician-1: 3.14±0.58, Physician-2: 3.15±0.58). The semi-automated method produced tumor volumes that were not statistically different from those by experts' manual operation. Furthermore, the volume change in the two sequential studies had no statistical difference between semi-automated and manual methods.

CONCLUSIONS

Our semi-automated method could define the liver SUV robustly as the threshold value used for tumor volume measurements according to PERCIST. The method could avoid possible subjective bias of manual liver VOI placement and is thus expected to improve clinical performance of volume-based parameters for prediction of cancer treatment response.

PET/CT evaluation of response to chemotherapy in non-small cell lung cancer: PET response criteria in solid tumors (PERCIST) versus response evaluation criteria in solid tumors (RECIST)

BACKGROUND

(18)F-FDG PET/CT is increasingly used in evaluation of treatment response for patients with non-small cell lung cancer (NSCLC). There is a need for an accurate criterion to evaluate the effect and predict the prognosis. The aim of this study is to evaluate therapeutic response in NSCLC with comparing PET response criteria in solid tumors (PERCIST) to response evaluation criteria in solid tumors (RECIST) criteria on PET/CT.

METHODS

Forty-four NSCLC patients who received chemotherapy but no surgery were studied. Chemotherapeutic responses were evaluated using (18)F-FDG PET and CT according to the RECIST and PERCIST methodologies. PET/CT scans were obtained before chemotherapy and after 2 or 4-6 cycles' chemotherapy. The percentage changes of tumor longest diameters and standardized uptake value (SUV) (corrected for lean body mass, SUL) before and after treatment were compared using paired t-test. The response was categorized into 4 levels according to RECIST and PERCIST: CR (CMR) =1, PR (PMR) =2, SD (SMD) =3, PD (PMD) =4. Pearson chi-square test was used to compare the proportion of four levels in RECIST and PERCIST. Finally the relationship between progression-free survival (PFS) and clinicopathologic parameters (such as TNM staging, percentage changes in diameters and SUL, RECIST and PERCIST results etc.) were evaluated using univariate and multivariate Cox proportional hazards regression method.

RESULTS

The difference of percentage changes between diameters and SUL was not significant using paired t-test (t=-1.69, P=0.098). However the difference was statistically significant in the 40 cases without increasing SUL (t=-3.31, P=0.002). The difference of evaluation results between RECIST and PERCIST was not significant by chi-square test (χ(2)=5.008, P=0.171). If RECIST evaluation excluded the new lesions which could not be found or identified on CT images the difference between RECIST and PERCIST was significant (χ(2)=11.759, P=0.007). Reduction rate of SULpeak (%), RECIST and PERCIST results were significant factors in univariate Cox analysis. But Multivariate Cox proportional hazards regression analysis demonstrated that only PERCIST was a significant factor for predicting DFS [hazard ratio (HR), 3.20; 95% (CI), 1.85-5.54; P<0.001].

CONCLUSIONS

PERCIST and RECIST criteria have good consistency and PERCIST (or PET) is more sensitive in detecting complete remission (CR) and progression. PERCIST might be the significant predictor of outcomes. The combination of PERCIST and RECIST would provide clinicians more accurate information of therapeutic response in earlier stage of treatment.

Repeatability of metabolically active tumor volume measurements with FDG PET/CT in advanced gastrointestinal malignancies: a multicenter study

PURPOSE

To evaluate the feasibility and repeatability of various metabolically active tumor volume ( MATV metabolically active tumor volume ) quantification methods in fluorine 18 fluorodeoxyglucose ( FDG fluorine 18 fluorodeoxyglucose ) positron emission tomography (PET)/computed tomography (CT) in a multicenter setting and propose the optimal MATV metabolically active tumor volume method together with the minimal threshold for future response evaluation studies.

MATERIALS AND METHODS

The study was approved by the institutional review board of all four participating centers, and patients provided written informed consent. Thirty-four patients with advanced gastrointestinal malignancies underwent two FDG fluorine 18 fluorodeoxyglucose PET/CT examinations within 1 week. MATV metabolically active tumor volume s were defined semiautomatically with 27 variations of tumor delineation methods with different reference values. Feasibility was determined as the percentage of successful tumor segmentations per MATV metabolically active tumor volume method. Repeatability was determined with intraclass correlation coefficients, Bland-Altman plots, and limits of agreement ( LOA limit of agreement s) of the percentage difference between the test and repeat test measurements. In addition, LOA limit of agreement variability per center was investigated.

RESULTS

In total, 136 lesions were identified. Feasibility of tumor segmentation ranged from 54% to 100% (74-136 of 136 lesions); repeatability was evaluated for 19 MATV metabolically active tumor volume methods with feasibility of greater than 95%. The median MATV metabolically active tumor volume derived with 50% threshold of mean standardized uptake value ( SUV standardized uptake value ) of a sphere of 12-mm diameter with highest local intensity ( SUVhp mean SUV of a sphere of 12-mm diameter with highest local intensity ), which may not include the voxel with highest SUV standardized uptake value corrected for local background, was 5.7 and 6.1 mL for test and retest scans, respectively, with a relative LOA limit of agreement of 36.1%. Comparable repeatability was found between centers. A difference in uptake time between scan 1 and 2 of 15 minutes or longer had a minor negative influence on repeatability.

CONCLUSION

MATV metabolically active tumor volume measured with 50% of SUVhp mean SUV of a sphere of 12-mm diameter with highest local intensity corrected for local background is recommended in multicenter FDG fluorine 18 fluorodeoxyglucose PET/CT studies on the basis of a high feasibility (96%) and repeatability ( LOA limit of agreement of 36.1%).

The intensity of radiotherapy-elicited immune response is associated with esophageal cancer clearance

Radiation therapy is one of the standard therapeutic modalities for esophageal cancer, achieving its main antitumor efficacy through DNA damage. However, accumulating evidence shows that radiotherapy can substantially alter the tumor microenvironment, particularly with respect to its effects on immune cells. We hypothesized that the immune response elicited by radiotherapy may be as important as the radiation itself for successful treatment. More specifically, immunomodulatory cytokines may enhance the effectiveness of radiotherapy. To investigate this hypothesis, we measured changes in the serum interferon-gamma (IFN-γ) and interleukin-2 (IL-2) concentrations during radiotherapy and compared these modifications with outcomes. We found that serum concentrations of IL-2 and IFN-γ were positively associated with local response to radiotherapy in esophageal cancer. More generally, the intensity of the radiotherapy-elicited immune response was positively associated with local response to radiotherapy in esophageal cancer. Changes in serum IL-2 and IFN-γ concentrations were further associated with increased risks of acute hematologic toxicity and acute organ toxicity of the esophagus, lung, and skin. These results suggest that deciphering the mechanisms of radiotherapy-elicited immune response may help in the development of therapeutic interventions that would enhance the efficacy of radiotherapy and convert some ineffective responses to effective responses.

Is FDG -PET-CT a valuable tool in prediction of persistent disease in head and neck cancer

OBJECTIVES

To evaluate accuracy of FDG-PET CT in prediction of persistent disease in head and neck cancer cases and to determine prognostic value of metabolic tumor response.

MATERIALS AND METHODS

Between 2009 and 2011, 46 patients with squamous cell carcinoma of head and neck receiving PET-CT were treated with definitive radiotherapy, with or without chemotherapy. There were 29 nasopharyngeal, 11 hypopharyngeal, 3 oropharyngeal and 3 laryngeal cancer patients, with a median age of 50.5 years (range 16-84), 32 males and 14 females. All patients were evaluated with PET-CT median 3-5 months (2.4-9.4) after completion of radiotherapy.

RESULTS

After a median 20 months of follow up, complete metabolic response was observed in 63% of patients. Suspicious residual uptake was present in 10.9% and residual metabolic uptake in 26.0% of patients. The overall sensitivity, specificity, positive predictive value and negative predictive value of FDG-PET-CT for detection of residual disease was 91% and 81%, 64% and 96% respectively. Two year LRC was 95% in complete responders while it was 34% in non-complete responders.

CONCLUSIONS

FDG PET CT is a valuable tool for assessment of treatment response, especially in patients at high risk of local recurrence, and also as an indicator of prognosis. Definitely more precise criteria are required for assessment of response, there being no clear cut uptake value indicating residual disease. Futhermore, repair processes of normal tissue may consume glucose which appear as increased uptake in control FDG PET CT.

SKI-II reverses the chemoresistance of SGC7901/DDP gastric cancer cells

Cisplatin is frequently used in treating gastric cancers; however, acquired resistance to the drug often reduces the efficacy of therapy. The present study analyzed the efficacy of the combination of 4-[4-(4-chloro-phenyl)-thiazol-2-ylamino]-phenol (SKI-II) and cisplatin [cis-diamminedichloroplatinum (II); DDP] on the gastric cancer SGC7901/DDP cell line. The results revealed that SKI-II and DDP had a clear synergistic effect. Glutathione (GSH) and glutathione S-transferase (GST) levels decreased significantly subsequent to the cells being treated with the combination of DDP and SKI-II compared with the cells that were treated with DDP or SKI-II alone. Phosphorylated extracellular-signal-regulated kinase (p-ERK) and phosphorylated c-Jun N-terminal kinase (p-JNK) expression levels also decreased following treatment with SKI-II. The results suggested that SKI-II is able to reverse the drug resistance in human gastric carcinoma cells and enhance the antitumor effect of DDP through the ras/mitogen-activated protein kinase (MAPK) proliferation pathway.

Differentiated thyroid cancer: a new perspective with radiolabeled somatostatin analogues for imaging and treatment of patients

BACKGROUND

The expression of somatostatin receptors (SSTR) in thyroid cells may offer the possibility to identify metastatic lesions and to select patients for peptide receptor radionuclide therapy (PRRT). We investigated (68)Ga-DOTATOC positron emission tomography/computed tomography (PET/CT) to select patients with progressive differentiated thyroid cancer (DTC) for PRRT as well as treatment response and toxicity in treated patients.

METHODS

We enrolled 41 patients with progressive radioiodine-negative DTC (24 women and 17 men; mean age=54.3 years, median=59 years, range=19-78 years). In all patients, [(18)F]FDG-PET/CT was performed to determine recurrent disease with enhanced glucose metabolism, and (68)Ga-DOTATOC PET/CT was used to identify SSTR expression. Dosimetric evaluation was performed with (111)In-DOTATOC scintigraphy. Eleven patients were treated with PRRT receiving a fractionated injection of 1.5-3.7 GBq (90)Y-DOTATOC/administration. Serial (68)Ga-DOTATOC PET/CT scans were performed in all treated patients to evaluate treatment response. Parameters provided by (68)Ga-DOTATOC PET/CT were analyzed as potential therapeutic predictors to differentiate responding from nonresponding. In all treated patients, adverse events and toxicity were recorded.

RESULTS

(68)Ga-DOTATOC PET/CT were positive in 24/41 of radioiodine-negative DTC patients. Based on the high expression of SSTR detected by (68)Ga-DOTATOC PET/CT, 13 patients were suitable for PRRT. Two out of 13 patients were not treated due to the lack of fulfillment of other study inclusion criteria. PRRT induced disease control in 7/11 patients (two partial response and five stabilization) with a duration of response of 3.5-11.5 months. Objective response was associated with symptoms relief. Functional volume (FV) over time obtained by PET/CT was the only parameter demonstrating a significant difference between lesions responding and nonresponding to PRRT (p=0.001). Main PRRT adverse events were nausea, asthenia, and transient hematologic toxicity. One patient experienced permanent renal toxicity.

CONCLUSIONS

In our series, SSTR imaging provided positive results in more than half of the cases with radioiodine-negative DTC, and about one third of patients were eligible for PRRT. (68)Ga-DOTATOC PET/CT seems a reliable tool both for patient selection and evaluation of treatment response. In our experience, FV determination over time seems to represent a reliable parameter to determine tumor response to PRRT, although further investigations are needed to better define its role.

(18)F-FDG-PET/CT in assessing response to neoadjuvant chemoradiotherapy for potentially resectable locally advanced esophageal cancer

PURPOSE

To correlate metabolic response to neoadjuvant chemoradiotherapy (NACR) on FDG-PET/CT using PERCIST-based criteria to pathologic and clinical response, and survival in patients with locally advanced esophageal cancer (LAEC).

MATERIALS AND METHODS

Forty-five patients with LAEC underwent PET/CT at baseline and after NACR. Tumors were evaluated using PERCIST (PET response criteria in solid tumors)-based criteria including SUL, SUL tumor/liver ratio, % change in SUL. These parameters were compared to pathology regression grade (PRG), clinical response (including residual or new disease beyond the surgical specimen), and overall survival.

RESULTS

On surgical pathology, there was complete or near-complete regression of tumor in 51.1 %, partial response in 42.2 %, and lack regression in 4.4 %. One patient (2.2 %) had progression of disease on imaging and did not undergo surgical resection. None of the baseline PET parameters had significant correlation to pathology regression grade or clinical response. On follow-up, a positive correlation was found between post-therapy SUL ratio, %∆ SUL and %∆ SUL ratio and clinical response (p = 0.025, 0.035, 0.030, respectively). A weak correlation was found between post-therapy SUL ratio to PRG (p = 0.049). A strong correlation was found between the metabolic response score and PRG (p = 0.002) as well as between metabolic response and clinical response (p < 0.001).

CONCLUSION

PERCIST-based metabolic response assessment to NACR in LAEC may correlate with clinical outcome and survival.

Determinants of response to neoadjuvant chemotherapy for esophageal cancer using 18F-fluorodeoxiglucose positron emission tomography (18F-FDG-PET)

BACKGROUND

(18)F-FDG-PET is potentially useful for evaluating response to neoadjuvant therapy for esophageal cancer. However, the optimal (18)F-FDG-PET parameter for evaluating the response to therapy and survival has not been established. This study aimed to select the best of the two parameters of fluorodeoxyglucose ((18)F-FDG)-positron emission tomography (PET): decreased ratio of maximal standardized uptake (SUVmax-DR) or absolute value of posttreatment SUVmax (post-SUVmax), in predicting response and survival of patients with esophageal cancer who underwent neoadjuvant chemotherapy.

METHODS

The study subjects were 211 consecutive patients with esophageal cancer who received neoadjuvant chemotherapy followed by surgery. (18)F-FDG-PET was performed before and 2-3 weeks after completion of neoadjuvant chemotherapy in assessment with pretreatment SUVmax (pre-SUVmax), post-SUVmax and SUVmax-DR.

RESULTS

The mean SUVmax decreased during neoadjuvant chemotherapy from 11.4 to 5.8, and the mean SUVmax-DR was 49.4%. Both post-SUVmax and SUVmax-DR correlated significantly with pathological response, although neither post-SUVmax nor SUVmax-DR could distinguish pathological complete response from pathological good response. The 5-year survival rate was significantly higher in patients with SUVmax-DR of >50% than those with <50% (56.5 vs. 39.6 %, p = 0.0137), and also significantly higher in patients with post-SUVmax of <3.5 than those with >3.5 (62.2 vs. 35.1%, p < 0.0001). Multivariate analysis identified post-SUVmax value, but not SUVmax-DR, as an independent prognostic factor in patients who underwent neoadjuvant chemotherapy.

CONCLUSIONS

Post-SUVmax is more useful for predicting survival of patients with esophageal cancer who undergo neoadjuvant therapy followed by surgery, although both SUVmax-DR and post-SUVmax equally correlate with pathological response.

Early PET/CT scan is more effective than RECIST in predicting outcome of patients with liver metastases from colorectal cancer treated with preoperative chemotherapy plus bevacizumab

Markers predictive of treatment effect might be useful to improve the treatment of patients with metastatic solid tumors. Particularly, early changes in tumor metabolism measured by PET/CT with (18)F-FDG could predict the efficacy of treatment better than standard dimensional Response Evaluation Criteria In Solid Tumors (RECIST) response.

METHODS

We performed PET/CT evaluation before and after 1 cycle of treatment in patients with resectable liver metastases from colorectal cancer, within a phase 2 trial of preoperative FOLFIRI plus bevacizumab. For each lesion, the maximum standardized uptake value (SUV) and the total lesion glycolysis (TLG) were determined. On the basis of previous studies, a ≤ -50% change from baseline was used as a threshold for significant metabolic response for maximum SUV and, exploratively, for TLG. Standard RECIST response was assessed with CT after 3 mo of treatment. Pathologic response was assessed in patients undergoing resection. The association between metabolic and CT/RECIST and pathologic response was tested with the McNemar test; the ability to predict progression-free survival (PFS) and overall survival (OS) was tested with the Log-rank test and a multivariable Cox model.

RESULTS

Thirty-three patients were analyzed. After treatment, there was a notable decrease of all the parameters measured by PET/CT. Early metabolic PET/CT response (either SUV- or TLG-based) had a stronger, independent and statistically significant predictive value for PFS and OS than both CT/RECIST and pathologic response at multivariate analysis, although with different degrees of statistical significance. The predictive value of CT/RECIST response was not significant at multivariate analysis.

CONCLUSION

PET/CT response was significantly predictive of long-term outcomes during preoperative treatment of patients with liver metastases from colorectal cancer, and its predictive ability was higher than that of CT/RECIST response after 3 mo of treatment. Such findings need to be confirmed by larger prospective trials.

Tumor quantification in clinical positron emission tomography

Positron emission tomography (PET) is used extensively in clinical oncology for tumor detection, staging and therapy response assessment. Quantitative measurements of tumor uptake, usually in the form of standardized uptake values (SUVs), have enhanced or replaced qualitative interpretation. In this paper we review the current status of tumor quantification methods and their applications to clinical oncology. Factors that impede quantitative assessment and limit its accuracy and reproducibility are summarized, with special emphasis on SUV analysis. We describe current efforts to improve the accuracy of tumor uptake measurements, characterize overall metabolic tumor burden and heterogeneity of tumor uptake, and account for the effects of image noise. We also summarize recent developments in PET instrumentation and image reconstruction and their impact on tumor quantification. Finally, we offer our assessment of the current development needs in PET tumor quantification, including practical techniques for fully quantitative, pharmacokinetic measurements.

Relevance of [18F]fluorodeoxyglucose positron emission tomography-positive lymph nodes after neoadjuvant chemotherapy for squamous cell oesophageal cancer

Background

Several studies have examined the clinical significance of metabolic response in primary tumours by [18F]fluorodeoxyglucose positron emission tomography (18F-FDG-PET) in patients with oesophageal cancer who undergo neoadjuvant therapy. The relevance of the metabolic response in lymph nodes is unclear.

Methods

Consecutive patients with oesophageal cancer who underwent neoadjuvant chemotherapy followed by surgery were studied. 18F-FDG-PET was performed before and 2–3 weeks after completion of neoadjuvant chemotherapy, assessing FDG uptake in primary tumours and lymph nodes considered to be metastatic.

Results

Before therapy, 156 (73·9 per cent) of 211 patients had PET-positive nodes, of whom 89 (57.1 per cent) had no evidence of metabolic activity in these lymph nodes following chemotherapy. There was a significant relationship between post-treatment lymph node status assessed by FDG-PET and numbers of pathologically confirmed metastatic lymph nodes. Patients with post-treatment PET-positive nodes had shorter survival than those without (5-year survival rate 25 versus 62·6 per cent; P &lt; 0·001). There was no difference in survival between patients with PET-positive nodes before but not after therapy and patients who had PET-negative nodes throughout (5-year survival rate 59 versus 71 per cent respectively; P = 0·207). Multivariable analysis identified post-treatment nodal status assessed by FDG-PET and tumour depth as independent prognostic factors.

Conclusion

Identification of PET-positive lymph nodes after completion of chemotherapy is a predictor of poor prognosis of patients with oesophageal cancer scheduled for surgery. FDG-PET lymph node status after neoadjuvant chemotherapy is more important than that before chemotherapy.

Evaluating the role of fluorodeoxyglucose positron emission tomography-computed tomography in multi-disciplinary team recommendations for oesophago-gastric cancer

BACKGROUND

National guidelines recommend that fluorodeoxyglucose positron emission tomography-computed tomography (PET-CT) is performed in all patients being considered for radical treatment of oesophageal or oesophago-gastric cancer without computerised tomography scan (CTS) evidence of metastasis. Guidance also mandates that all patients with cancer have treatment decisions made within the context of a multi-disciplinary team (MDT) meeting. Little is known, however, about the influence of PET-CT on decision making within MDTs. The aim of this study was to assess the role of PET-CT in oesophago-gastric cancer on MDT decision making.

METHODS

A retrospective analysis of a prospectively held database of all patients with biopsy-proven oesophageal or oesophago-gastric cancer discussed by a specialist MDT was interrogated. Patients selected for radical treatment without CTS evidence of M1 disease were identified. The influence of PET-CT on MDT decision making was examined by establishing whether the PET-CT confirmed CTS findings of M0 disease (and did not change the patient staging pathway) or whether the PET-CT changed the pathway by showing unsuspected M1 disease, refuting CTS suspicious metastases, or identifying another lesion (needing further investigation).

RESULTS

In 102 MDT meetings, 418 patients were discussed, of whom 240 were initially considered for radical treatment and 238 undergoing PET-CT. The PET-CT confirmed CTS findings for 147 (61.8%) and changed MDT recommendations in 91 patients (38.2%) by (i) identifying M1 disease (n=43), (ii) refuting CTS suspicions of M1 disease (n=25), and (iii) identifying new lesions required for investigations (n=23).

CONCLUSION

The addition of PET-CT to standard staging for oesophageal cancer led to changes in MDT recommendations in 93 (38.2%) patients, improving patient selection for radical treatment. The validity of the proposed methods for evaluating PET-CT on MDT decision making requires more work in other centres and teams.

Overview of positron emission tomography, hybrid positron emission tomography instrumentation, and positron emission tomography quantification

Positron emission tomography (PET) is a powerful quantitative molecular imaging technique that is complementary to structural imaging techniques for purposes of disease detection and characterization. This review article provides a brief overview of PET, hybrid PET instrumentation, and PET quantification.