18F-FDG PET/CT for early prediction of response to neoadjuvant chemotherapy in breast cancer

Molecular and functional imaging in cancer-targeted therapy: current applications and future directions

Targeted anticancer drugs block cancer cell growth by interfering with specific signaling pathways vital to carcinogenesis and tumor growth rather than harming all rapidly dividing cells as in cytotoxic chemotherapy. The Response Evaluation Criteria in Solid Tumor (RECIST) system has been used to assess tumor response to therapy via changes in the size of target lesions as measured by calipers, conventional anatomically based imaging modalities such as computed tomography (CT), and magnetic resonance imaging (MRI), and other imaging methods. However, RECIST is sometimes inaccurate in assessing the efficacy of targeted therapy drugs because of the poor correlation between tumor size and treatment-induced tumor necrosis or shrinkage. This approach might also result in delayed identification of response when the therapy does confer a reduction in tumor size. Innovative molecular imaging techniques have rapidly gained importance in the dawning era of targeted therapy as they can visualize, characterize, and quantify biological processes at the cellular, subcellular, or even molecular level rather than at the anatomical level. This review summarizes different targeted cell signaling pathways, various molecular imaging techniques, and developed probes. Moreover, the application of molecular imaging for evaluating treatment response and related clinical outcome is also systematically outlined. In the future, more attention should be paid to promoting the clinical translation of molecular imaging in evaluating the sensitivity to targeted therapy with biocompatible probes. In particular, multimodal imaging technologies incorporating advanced artificial intelligence should be developed to comprehensively and accurately assess cancer-targeted therapy, in addition to RECIST-based methods.

miR-638 Serves as a Biomarker of 5-Fluorouracil Sensitivity to Neoadjuvant Chemotherapy in Breast Cancer

Purpose

Neoadjuvant chemotherapy (NAC) is widely used to treat breast cancer (BC). The prediction and evaluation of chemotherapy responses remains a significant challenge.

Methods

MicroRNAs (miRNAs) play a crucial role in cancer drug resistance. We used a miRNA microarray and identified that miR-638 is downregulated in chemoresistant cases. However, the exact role of miR-638 and the underlying mechanisms of chemoresistance remain unclear. Using real-time quantitative reverse transcription polymerase chain reaction, we found significant downregulation of miR-638 in chemoresistant patients compared with chemosensitive patients. To explore the function of miR-638, we overexpressed and inhibited miR-638 expression in MDA-MB-231 and MCF-7 cells by transfecting them with miR-638 mimics and miR-638 inhibitor, respectively. Cell proliferation and apoptosis were measured using MTS and flow cytometry, respectively. A minimal patient-derived xenograft (MiniPDX™) model was established to evaluate the chemosensitivity to different drugs.

Results

The results showed that cell proliferation decreased and cell apoptosis increased in cells transfected with the miR-638 mimic, and cell proliferation and apoptosis were reversed with transfection of miR-638 inhibitor compared with the control group. Among patients who received 5-fluorouracil (5-FU), miR-638 expression levels were lower in the chemoresistant group than in the chemosensitive group. The MiniPDX™ model showed that MDA-MB-231 cells overexpressing miR-638 were more susceptible to 5-FU treatment in vivo.

Conclusion

We provided evidence of acquired resistance to 5-FU caused by miR-638 deficiency. Alterations in miR-638 may be used with 5-FU chemotherapy during NAC for BC.

Identification of miRNA Signature in Breast Cancer to Predict Neoadjuvant Chemotherapy Response

Background: Chemotherapy failure causes high breast cancer recurrence and poor patient prognosis. Thus, we studied a cohort of novel biomarkers to predict chemotherapeutic response in breast cancer. In this study, miRNA expression profiling was performed on 10 breast cancer punctured specimens sensitive to chemotherapy (MP grade 4, 5) and 10 chemotherapy resistant (MP grade 1). Differentially expressed miRNAs were verified by qRT-PCR in 60 initial samples, 59 validated samples and 71 independent samples. A miRNA signature was generated using a Logistic regression model. A receiver operating characteristic (ROC) test was used to assess specificity and sensitivity of single miRNA and miRNA signature. Target genes regulated by miRNAs and their involved signaling pathways were analyzed using GO enrichment and KEGG software. MiRNAs expression were separately compared with ER, PR, HER2 immunohistochemical staining and different drugs. qRT-PCR showed that the high expression of miR-23a-3p, miR-200c-3p, miR-214-3p and the low expression of miR-451a and miR-638 were closely related to chemoresistance. According to the formula for calculating the drug resistance risk, patients in the high-risk group were more likely to develop chemotherapy resistance than the low-risk group. Bioinformatics analysis showed that 5 miRNAs and target genes are mainly involved in p53, ubiquitin-mediated proteolysis, mTOR, Wnt, cells skeletal protein regulation, cell adhesion and ErbB signaling pathways. miR-451a expression was associated with ER, HER-2 status and anthracyclines. A miRNA signature of chemotherapeutic response may be clinically valuable for improving current chemotherapy regimens of individual treatment for patients with breast cancer.

The role of basal 18F-FDG PET/CT maximum standard uptake value and maximum standard uptake change in predicting pathological response in breast cancer patients receiving neoadjuvant chemotherapy

OBJECTIVE

The aim of this study was to determine the role of 18F-FDG PET/CT in predicting pathological response among patients diagnosed with local or locally advanced breast cancer and receiving neoadjuvant chemotherapy (NAC).

METHODS

Basal SUVmax value were analyzed in 212 patients and 142 of these patients had posttreatment SUVmax value. Overall pathological complete response (pCRC) was defined as no evidence of residual invasive cancer in breast (pCRB) and axilla (pCRA). Basal SUVmax value of the breast (SUVmaxBI) and axilla (SUVmaxAI) and change in SUVmax of the breast (ΔSUVmaxB) and axilla (ΔSUVmaxA) were measured. The optimal cutoff value of SUVmax and ΔSUVmax were determined by receiver operating characteristic curve analysis.

RESULTS

The number of patients with pCRB was 85 (40.1%), pCRA was 76 (42.5%) and pCRC was 70 (33%). In the artificial neural network-based analysis the ΔSUVmaxB (100%) was the most important variable for predicting pCRB. ΔSUVmaxA (100%) was the most important variable in estimation of pCRA. When pCRC was evaluated, the highest relation was found with ΔSUVmaxB. When the ΔSUVmaxB cutoff value for pCRB and pCRC accepted as ≤-87.9%, its sensitivity was 82.3 and 82.4%, and specificity was 72.5% and 65.9%, respectively (P < 0.001 and P < 0.001, respectively). When the ΔSUVmaxA cutoff value for pCRA and pCRC accepted as ≤-86.6%, its sensitivity was 94.3% and 97.6%, and specificity was 31.3% and 28.2%, respectively (P = 0.017 and P = 0.024, respectively).

CONCLUSION

Albeit varies according to the molecular subtypes of the breast cancer during NAC, ΔSUVmax value seems to be the most strong factor associated with pCR.

Accuracy of metabolic volume and total glycolysis among six threshold-based target segmentation algorithms

OBJECTIVE

This study aimed to evaluate the accuracy of six threshold-based segmentation methods with different target-to-background ratios (TBR), images with different voxel sizes and image noise, in measuring metabolic volume (MV) and total glycolysis (TG).

METHODS

A standard body phantom consisting of six spheres (inner diameters of 37, 28, 22, 17, 13, and 10 mm) was filled with ¹⁸F-FDG solution. The background radioactivity level was 2.65 kBq/mL, and the TBRs were 4 and 8. PET data were acquired for 30 min with list mode. PET data for 30 and 3 min were reconstructed with a three-dimensional ordered subset expectation maximization algorithm plus time-of-flight information with images with 2 and 4 mm isotropic voxels. The six methods examined were absolute standardized uptake value (SUV) of 2.5 (SUV_2.5), 41%, 50%, adaptive 41%, and adaptive 50% thresholds of maximum SUV (Th₄₁, Th₅₀, ThA₄₁, and ThA₅₀, respectively); and the contrast-oriented algorithm (Th_COA). Segmented MV and TG were compared with the actual inner volume and expressed as percentages (%MV_seg and %TG_seg, respectively). In addition, the segmented MV was converted to the diameter, and the differences of it from the reference diameter were compared among six methods.

RESULTS

The Th_COA method yielded the most accurate measurements of %MV_seg and %TG_seg; the difference between %MV_seg or %TG_seg and its reference were smaller than 10% in 30-min and 15% in 3-min images, but the segmented contour was almost the same as the reference diameter. Measurements with Th₅₀ and Th_COA were highly accurate for both %MV_seg and %TG_seg in the large spheres, and the adaptive threshold methods, including ThA₄₁, ThA₅₀, and Th_COA, were also highly accurate in the small spheres. The voxel sizes affected the accuracy of %MV_seg and %TG_seg with a TBR of 4 in any threshold-based methods.

CONCLUSIONS

Of the six threshold-based segmentation methods studied, Th_COA was the most accurate method for evaluating MV and TG and had only minor dependence on TBRs and sphere size. The small voxel sizes improved the variation of the accuracy in low TBR.

Examining the evolving utility of 18FDG-PET/CT in breast cancer recurrence

Many studies have demonstrated the utility of ¹⁸fluorodeoxyglucose-positron emission tomography/computed tomography (¹⁸FDG-PET/CT) scan in evaluating breast cancer recurrence in subsets of patients based on age, histological subtype and cancer stage to guide response to conventional chemoradiation guidelines during treatment of metastatic breast cancer disease. This literature review focuses on the breakthrough of ¹⁸FDG-PET/CT imaging within the paradigm of breast cancer oncology centered toward improving risk stratification and prognostication of disease relapse based on cancer molecular phenotypes, tumor markers, early metabolic activity and response to neoadjuvant chemotherapy (NAC). The authors consider the rapid shift toward biomarker based molecular tracers to quantify treatment response and pathologic complete response with more recent imaging modalities such as dedicated breast positron emission tomography (dbPET), and the advantages afforded by this multisystem approach.

Imaging Tumor Proliferation in Breast Cancer: Current Update on Predictive Imaging Biomarkers

Uncontrolled growth is a hallmark of cancer; imaging cell proliferation can provides an early indicator of therapeutic response. This capability is especially well-matched to the emerging cell cycle-specific chemotherapeutics with the goal of identifying patients that benefit from these treatments early in the course of treatment to guide personalized therapy. This article focuses on investigational cell proliferation imaging PET radiotracers to evaluate tumor proliferation in the setting of cell cycle-targeted chemotherapy and endocrine therapy for metastatic breast cancer.

Prognostic factors in breast cancer patients evaluated by positron-emission tomography/computed tomography before neoadjuvant chemotherapy

Neoadjuvant chemotherapy (NAC) is a significant modality in breast cancer therapy. We sought to characterize prognostic factors in patients scheduled for NAC who had a pretreatment positron-emission tomography paired with diagnostic quality contrast-enhanced computed tomography (CT) (positron-emission tomography/CT [PET/CT]). A total of 118 breast cancer patients were analyzed through chart review who underwent pretreatment PET/CT imaging and received NAC from 2008 to 2014. We collected information on molecular markers, PET/CT, pathologic complete response (pCR), survival, and disease status. Pretreatment standard uptake value (SUV) max of the primary breast tumor showed no relationship to pCR; however, there was a statistically significant relationship with relapse-free survival (RFS) using univariate cox regression (P = 0.03, odds ratio (OR) = 1.06 [1.01-1.12]) with comparable findings observed with overall survival (OS). Multivariate analysis revealed SUV max to be significantly correlated with shortened OS (P = 0.022, OR = 1.08 [1.01-1.16]), with a similar trend reported for RFS. By pathological subtype, this correlation was the strongest within hormone receptor (HR+)/human epidermal growth factor receptor 2 (HER2-) tumors. In addition, Kaplan-Meier estimates demonstrated a significant difference between the RFS of triple-negative tumors and HER2 positive tumors (P = 0.001). Interestingly, within this cohort, multivariate Cox regression analysis showed HER2 positivity to be associated with favorable outcome (P = 0.04, HR = 0.22 [0.05-0.94]). These findings demonstrate a significant association between SUV max of HR+/HER2-- tumors and relapse-free and OS. Furthermore, highlighted here is the favorable survival in the once classically aggressive HER2+ breast cancer subgroup.

Role of Fludeoxyglucose in Breast Cancer: Treatment Response

After an overview of the principles of fludeoxyglucose-PET/computed tomography (CT) in breast cancer, its advantages and limits to evaluate treatment response are discussed. The metabolic information is helpful for early assessment of the response to neoadjuvant chemotherapy and could be used to monitor treatment, especially in aggressive breast cancer subtypes. PET/CT is also a powerful method for early assessment of the treatment response in the metastatic setting. It allows evaluation of different sites of metastases in a single examination and detection of a heterogeneous response. However, to use PET/CT to assess responses, methodology for image acquisition and analysis needs standardization.

Optical Mammography in Patients with Breast Cancer Undergoing Neoadjuvant Chemotherapy: Individual Clinical Response Index

RATIONALE AND OBJECTIVES

We present an optical mammography study that aims to develop quantitative measures of pathologic response to neoadjuvant chemotherapy (NAC) in patients with breast cancer. Such quantitative measures are based on the concentrations of oxyhemoglobin ([HbO₂]), deoxyhemoglobin ([Hb]), total hemoglobin ([HbT]), and hemoglobin saturation (SO₂) in breast tissue at the tumor location and at sequential time points during chemotherapy.

MATERIALS AND METHODS

Continuous-wave, spectrally resolved optical mammography was performed in transmission and parallel-plate geometry on 10 patients before treatment initiation and at each NAC administration (mean number of optical mammography sessions: 12, range: 7-18). Data on two patients were discarded for technical reasons. The patients were categorized as responders (R, >50% decrease in tumor size), or nonresponders (NR, <50% decrease in tumor size) based on imaging and histopathology results.

RESULTS

At 50% completion of the NAC regimen (therapy midpoint), R (6/8) demonstrated significant decreases in SO₂ (-27% ± 4%) and [HbT] (-35 ± 4 µM) at the tumor location with respect to baseline values. By contrast, NR (2/8) showed nonsignificant changes in SO₂ and [HbT] at therapy midpoint. We introduce a cumulative response index as a quantitative measure of the individual patient's response to therapy. At therapy midpoint, the SO₂-based cumulative response index had a sensitivity of 100% and a specificity of 100% for the identification of R.

CONCLUSIONS

These results show that optical mammography is a promising tool to assess individual response to NAC at therapy midpoint to guide further decision making for neoadjuvant therapy.

Monitoring tumor response to neoadjuvant chemotherapy using MRI and 18F-FDG PET/CT in breast cancer subtypes

Purpose

To explore guidelines on the use of MRI and PET/CT monitoring primary tumor response to neoadjuvant chemotherapy (NAC), taking breast cancer subtype into account.

Materials and methods

In this prospective cohort study, 188 women were included with stages II and III breast cancer. MRI and ¹⁸F-FDG-PET/CT were acquired before and during NAC. Baseline pathology was assessed from tumor biopsy. Tumors were stratified into HER2-positive, ER-positive/HER2-negative (ER-positive), and ER-negative/PR-negative/HER2-negative (triple-negative) subtypes, and treated according to subtype. Primary endpoint was pathological complete response (pCRmic) defined as no or only small numbers of scattered invasive tumor cells. We evaluated imaging scenarios using MRI only, PET/CT only, and combinations.

Results

pCRmic was found in 35/46 (76.1%) of HER2-positive, 11/87 (12.6%) of ER-positive, and 31/55 (56.4%) of triple-negative tumors. For HER2-positive tumors, MRI yielded the strongest predictor (AUC: 0.735; sensitivity 36.2%), outperforming PET/CT (AUC: 0.543; p = 0.04), and with comparable results to combined imaging (AUC: 0.708; p = 0.213). In ER-positive tumors, the combination of MRI and PET/CT was slightly superior (AUC: 0.818; sensitivity 55.8%) over MRI alone (AUC: 0.742; p = 0.117) and PET/CT alone (AUC: 0.791). However, even though relatively large numbers of ER-positive tumor patients were included, no significant differences were yet found. For triple-negative tumors, MRI (AUC: 0.855; sensitivity 45.4%), PET/CT (AUC: 0.844; p = 0.220) and combined imaging (AUC: 0.868; p = 0.213) yielded comparable results.

Conclusions

For HER2-positive tumors, MRI shows significant advantage over PET/CT. For triple-negative tumors, comparable results were seen for MRI, PET/CT and combined imaging. For ER-positive tumors, combining MRI with PET/CT may result in optimal response monitoring, although not yet significantly.

Value of volume-based metabolic parameters for predicting survival in breast cancer patients treated with neoadjuvant chemotherapy

We evaluated the role of metabolic parameters in the prediction of disease recurrence in operable invasive ductal breast cancer patients treated with neoadjuvant chemotherapy (NAC).We retrospectively evaluated 139 female patients (mean age, 46.5 years; range: 27-72 years) with invasive ductal breast cancer, treated with NAC followed by surgery. All patients underwent F-fluorodeoxyglucose positron emission tomography/computed tomography and magnetic resonance imaging at baseline and after completion of NAC before surgery. The prognostic significance of clinicopathological and imaging parameters for disease-free survival (DFS) was evaluated.Recurrence of cancer was detected in 31 of 139 patients (22.3%; follow-up period: 6-82 months). Baseline maximum standardized uptake value, metabolic tumor volume (MTV), and reduction rate (RR) of MTV after NAC were significant independent prognostic factors for DFS in a multivariate analysis (all P < 0.05). The survival functions differed significantly between low and high histological grades (P < 0.001). DFS of the patients with high baseline MTV (≥5.23 cm) was significantly poorer than that of low MTV patients (P = 0.019). The survival function of the group with low RR of MTV after NAC (≤90.72%) was poorer than the higher RR of the MTV group (P = 0.008).Our findings suggest that breast cancer patients who have a high histological grade, large baseline MTV, or a small RR of MTV after NAC should receive great attention to check for possible recurrence.

Evolution and Developments in Instrumentation for Positron Emission Mammography

Molecular imaging using high-resolution PET instrumentation is now playing a pivotal role in basic and clinical research. The development of optimized detection geometries combined with high-performance detector technologies and compact designs of PET tomographs have become the goal of active research groups in academic and corporate settings. Significant progress has been achieved in the design of commercial PET instrumentation in the last decade allowing a spatial resolution of about 4 to 6 mm to be reached for whole-body imaging, about 2.4 mm for PET cameras dedicated for brain imaging, and submillimeter resolution for female breast, prostate, and small-animal imaging. In particular, significant progress has been made in the design of dedicated positron emission mammography (PEM) units. The initial concept suggested in 1993 consisted of placing 2 planar detectors capable of detecting the 511-keV annihilation photons in a conventional mammography unit. Since that time, many different design paths have been pursued and it will be interesting to see which technologies become the most successful in the future. This paper discusses recent advances in PEM instrumentation and the advantages and challenges of dedicated standalone and dual-modality imaging systems. Future opportunities and the challenges facing the adoption of PEM imaging instrumentation and its role in clinical and research settings are also addressed.

PET/MR in Breast Cancer

Breast cancer is an international public health concern in which an optimal treatment plan requires a precise staging. Both MRI and PET imaging techniques have made significant progress in the last decades with constant improvements that made both modalities clinically relevant in several stages of breast cancer management and follow-up. On one hand, specific breast MRI permits high diagnostic accuracy for local tumor staging, and whole-body MRI can also be of great use in distant staging, eventually accompanied by organ-specific MRI sequences. Moreover, many different MRI sequences can be performed, including functional MRI, letting us foresee important improvements in breast cancer characterization in the future. On the contrary, (18)F-FDG-PET has a high diagnostic performance for the detection of distant metastases, and several other tracers currently under development may profoundly affect breast cancer management in the future with better determination of different types of breast cancers allowing personalized treatments. As a consequence PET/MR is a promising emerging technology, and it is foreseeable that in cases where both PET and MRI data are needed, a hybrid acquisition is justified when available. However, at this stage of deployment of such hybrid scanners in a clinical setting, more data are needed to demonstrate their added value beyond just patient comfort of having to undergo a single examination instead of two, and the higher confidence of diagnostic interpretation of these co-registered images. Optimized imaging protocols are still being developed and are prone to provide more efficient hybrid protocols with a potential improvement in diagnostic accuracy. More convincing studies with larger number of patients as well as cost-effectiveness studies are needed. This article provides insights into the current state-of-the-art of PET/MR in patients with breast cancer and gives an outlook on future developments of both imaging techniques and potential applications in the future.

Utility of FDG-PET/CT in the evaluation of the response of locally advanced breast cancer to neoadjuvant chemotherapy

Neoadjuvant chemotherapy (NAC) is effective in down-staging a primary tumor before surgery, and quick differentiation between responders to NAC and nonresponders is needed. We investigated the utility of [18F]fluorodeoxyglucose positron emission tomography (FDG-PET) and computed tomography (CT) in evaluating the therapeutic effectiveness of NAC. We investigated 25 patients who underwent NAC for stage II and III noninflammatory breast cancer. FDG-PET/CT was undertaken before and after NAC to determine the maximum standardized uptake value (SUVmax) reduction rate. Findings were compared with postoperative histopathologic evaluation of therapeutic response. It was not possible to accurately assess tumor response to NAC using CT. However, using the SUVmax reduction rate, we noted a significant difference (P=0.0420) between patients who were responsive and nonresponsive to NAC. The sensitivity and specificity were as high as 83.3% and 78.9%, respectively. This study demonstrated that FDG-PET/CT can differentiate responders from nonresponders. This improves patient management by avoiding unnecessary chemotherapy.

18F-FDG PET/CT to Predict Response to Neoadjuvant Chemotherapy and Prognosis in Inflammatory Breast Cancer

The aim of this prospective study was to assess the predictive value of (18)F-FDG PET/CT imaging for pathologic response to neoadjuvant chemotherapy (NACT) and outcome in inflammatory breast cancer (IBC) patients.

METHODS

Twenty-three consecutive patients (51 y ± 12.7) with newly diagnosed IBC, assessed by PET/CT at baseline (PET1), after the third course of NACT (PET2), and before surgery (PET3), were included. The patients were divided into 2 groups according to pathologic response as assessed by the Sataloff classification: pathologic complete response for complete responders (stage TA and NA or NB) and non-pathologic complete response for noncomplete responders (not stage A for tumor or not stage NA or NB for lymph nodes). In addition to maximum standardized uptake value (SUVmax) measurements, a global breast metabolic tumor volume (MTV) was delineated using a semiautomatic segmentation method. Changes in SUVmax and MTV between PET1 and PET2 (ΔSUV1-2; ΔMTV1-2) and PET1 and PET3 (ΔSUV1-3; ΔMTV1-3) were measured.

RESULTS

Mean SUVmax on PET1, PET2, and PET3 did not statistically differ between the 2 pathologic response groups. On receiver-operating-characteristic analysis, a 72% cutoff for ΔSUV1-3 provided the best performance to predict residual disease, with sensitivity, specificity, and accuracy of 61%, 80%, and 65%, respectively. On univariate analysis, the 72% cutoff for ΔSUV1-3 was the best predictor of distant metastasis-free survival (P = 0.05). On multivariate analysis, the 72% cutoff for ΔSUV1-3 was an independent predictor of distant metastasis-free survival (P = 0.01).

CONCLUSION

Our results emphasize the good predictive value of change in SUVmax between baseline and before surgery to assess pathologic response and survival in IBC patients undergoing NACT.

Role of positron emission tomography for the monitoring of response to therapy in breast cancer

This review considers the potential utility of positron emission tomography (PET) tracers in the setting of response monitoring in breast cancer, with a special emphasis on glucose metabolic changes assessed with (18)F-fluorodeoxyglucose (FDG). In the neoadjuvant setting of breast cancer, the metabolic response can predict the final complete pathologic response after the first cycles of chemotherapy. Because tumor metabolic behavior highly depends on cancer subtype, studies are ongoing to define the optimal metabolic criteria of tumor response in each subtype. The recent multicentric randomized AVATAXHER trial has suggested, in the human epidermal growth factor 2-positive subtype, a clinical benefit of early tailoring the neoadjuvant treatment in women with poor metabolic response after the first course of treatment. In the bone-dominant metastatic setting, there is increasing clinical evidence that FDG-PET/computed tomography (CT) is the most accurate imaging modality for assessment of the tumor response to treatment when both metabolic information and morphologic information are considered. Nevertheless, there is a need to define standardized metabolic criteria of response, including the heterogeneity of response among metastases, and to evaluate the costs and health outcome of FDG-PET/CT compared with conventional imaging. New non-FDG radiotracers highlighting specific molecular hallmarks of breast cancer cells have recently emerged in preclinical and clinical studies. These biomarkers can take into account the heterogeneity of tumor biology in metastatic lesions. They may provide valuable clinical information for physicians to select and monitor the effectiveness of novel therapeutics targeting the same molecular pathways of breast tumor.

Syntheses and discovery of a novel class of cinnamic hydroxamates as histone deacetylase inhibitors by multimodality molecular imaging in living subjects

Histone deacetylases (HDAC) that regulate gene expression are being explored as cancer therapeutic targets. In this study, we focused on HDAC6 based on its ability to inhibit cancerous Hsp90 chaperone activities by disrupting Hsp90/p23 interactions. To identify novel HDAC6 inhibitors, we used a dual-luciferase reporter system in cell culture and living mice by bioluminescence imaging (BLI). On the basis of existing knowledge, a library of hydrazone compounds was generated for screening by coupling cinnamic hydroxamates with aldehydes and ketones. Potency and selectivity were determined by in vitro HDAC profiling assays, with further evaluation to inhibit Hsp90(α/β)/p23 interactions by BLI. In this manner, we identified compound 1A12 as a dose-dependent inhibitor of Hsp90(α/β)/p23 interactions, UKE-1 myeloid cell proliferation, p21(waf1) upregulation, and acetylated histone H3 levels. 1A12 was efficacious in tumor xenografts expressing Hsp90(α)/p23 reporters relative to carrier control-treated mice as determined by BLI. Small animal (18)F-FDG PET/CT imaging on the same cohort showed that 1A12 also inhibited glucose metabolism relative to control subjects. Ex vivo analyses of tumor lysates showed that 1A12 administration upregulated acetylated-H3 by approximately 3.5-fold. Taken together, our results describe the discovery and initial preclinical validation of a novel selective HDAC inhibitor.

99mTc-sestamibi using a direct conversion molecular breast imaging system to assess tumor response to neoadjuvant chemotherapy in women with locally advanced breast cancer

PURPOSE

The objective of this study was to determine the ability of breast imaging with 99mTc-sestamibi and a direct conversion-molecular breast imaging (MBI) system to predict early response to neoadjuvant chemotherapy (NAC).

METHODS

Patients undergoing NAC for breast cancer were imaged with a direct conversion-MBI system before (baseline), at 3 to 5 weeks after onset, and after completion of NAC. Tumor size and tumor-to-background (T/B) uptake ratio measured from MBI images were compared with extent of residual disease at surgery using the residual cancer burden.

RESULTS

Nineteen patients completed imaging and proceeded to surgical resection after NAC. Mean reduction in T/B ratio from baseline to 3 to 5 weeks for patients classified as RCB-0 (no residual disease), RCB-1 and RCB-2 combined, and RCB-3 (extensive residual disease) was 56% (SD, 0.20), 28% (SD, 0.20), and 4% (SD, 0.15), respectively. The reduction in the RCB-0 group was significantly greater than in RCB-1/2 (P = 0.036) and RCB-3 (P = 0.001) groups. The area under the receiver operator characteristic curve for determining the presence or absence of residual disease was 0.88. Using a threshold of 50% reduction in T/B ratio at 3 to 5 weeks, MBI predicted presence of residual disease at surgery with a diagnostic accuracy of 89.5% (95% confidence interval [CI], 0.64%-0.99%), sensitivity of 92.3% (95% CI, 0.74%-0.99%), and specificity of 83.3% (95% CI, 0.44%-0.99%). The reduction in tumor size at 3 to 5 weeks was not statistically different between RCB groups.

CONCLUSIONS

Changes in T/B ratio on MBI images performed at 3 to 5 weeks following initiation of NAC were accurate at predicting the presence or absence of residual disease at NAC completion.

Utility of MRI and PET/CT after neoadjuvant chemotherapy in breast cancer patients: correlation with pathological response grading system based on tumor cellularity

BACKGROUND

MRI and PET/CT are useful for assessing breast cancer patients after neoadjuvant chemotherapy (NAC).

PURPOSE

To investigate the utility of MRI and PET/CT in the prediction of pathologic response to neoadjuvant chemotherapy using Miller-Payne grading system in patients with breast cancer.

MATERIAL AND METHODS

From January 2008 to December 2010, 59 consecutive patients with pathologically proven breast cancer, who underwent neoadjuvant chemotherapy followed by surgery were retrospectively enrolled. The maximal diameter decrease rate and volume reduction rate by three-dimensional (3D) MRI and standardized uptake value (SUV) reduction rate by PET/CT were calculated and correlated with the Miller-Payne grading system using the Spearman rank correlation test. Patients with Miller-Payne grades 1 or 2 were classified into the non-responder group and patients with grades 3, 4, and 5 were in the responder group. To differentiate between responders and non-responders, receiver-operating characteristic (ROC) analysis was performed.

RESULTS

The volume reduction rate was 64.87 ± 46.95, diameter decrease rate was 48.09 ± 35.02, and SUV decrease rate was 62.10 ± 32.17. Among three parameters, the volume reduction rate was most correlated with histopathologic grades of regression (ρ = 0.755, P < .0001) followed by diameter decrease rate (ρ = 0.660, P < 0.0001), and SUV decrease rate of primary breast mass (ρ = 0.561, P = 0.0002). The area under the ROC curve (Az) value was largest in the volume reduction rate (Az = 0.9), followed by SUV decrease rate (Az = 0.875), and diameter decrease rate (Az = 0.849). The best cut-offs for differentiating responders from non-responders in the ROC curve analysis were a 50% decrease in diameter, 68.9% decrease in volume, and 60.1% decrease in SUV after NAC.

CONCLUSION

Volumetric measurement using 3D MRI combined with conventional diameter measurement may be more accurate to evaluate pathologic response after NAC.

MRI and FDG-PET for assessment of response to neoadjuvant chemotherapy in locally advanced rectal cancer

BACKGROUND

The purpose of this study was to assess the value of magnetic resonance imaging (MRI) and additional (18)F-fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) for tumor response to neoadjuvant chemotherapy (NAC) in patients with locally advanced rectal cancer (LARC).

METHODS

Data on 40 patients with LARC, who were treated with NAC and underwent MRI and FDG-PET/CT before and after NAC, were analyzed retrospectively. Surgery was performed at a median of 6 weeks after NAC and the images were compared with the histological findings. The tumor regression grade 3/4 was classified as a responder.

RESULTS

Sixteen patients were pathological responders. Receiver operating characteristic (ROC) analysis revealed that MRI total volume after NAC (MRI-TV2) and ΔMRI-TV had the highest performance to assess responders (area under the ROC curve [AUC] 0.849 and AUC 0.853, respectively). The reduction rate of the maximum standardized uptake value (ΔSUVmax) was also an informative factor (AUC 0.719). There seems no added value of adding FDG-PET/CT to MRI-TV2 and ΔMRI-TV in assessment of NAC responders judging from changes in AUC (AUC of ΔSUVmax and MRI-TV2 was 0.844, and AUC of ΔSUVmax and ΔMRI-TV was 0.846).

CONCLUSIONS

MRI-TV2 and ΔMRI-TV were the most accurate factors to assess pathological response to NAC. Although ΔSUVmax by itself was also informative, the addition of FDG-PET/CT to MRI did not improve performance. Patients with LARC who were treated by induction chemotherapy should receive an MRI examination before and after NAC to assess treatment response. A more than 70 % volume reduction shown by MRI volumetry may justify the omission of subsequent radiotherapy.

18FDG-PET for Early Prediction of Complete Response to Lapatinib and Capecitabine in HER2-Positive Metastatic Breast Cancer: A Case Report

Targeted therapies against HER2 (trastuzumab, lapatinib) have improved the efficacy of treatment and the outcome of patients with HER2-positive breast cancer. Lapatinib is a tyrosine kinase inhibitor targeting EGFR1 and HER2: it binds the intracellular domain of these receptors and blocks their downstream signaling pathways. In combination with capecitabine, it is the standard of care for patients with trastuzumab-resistant advanced breast cancer. We present the case of a patient exhibiting a complete and prolonged clinical response to second-line treatment with lapatinib and capecitabine after failure of trastuzumab-based therapy. 18FDG-PET allowed the detection of disease remission several months before computed tomography. Molecular imaging with 18FDG seems the most powerful way to measure the pharmacodynamic effects of targeted anticancer drugs. This case report confirms that18FDG-PET plays a key role not only in detecting metastatic disease but also in evaluating the response to HER2-directed therapy.

Positron emission tomography with [(18)F]-3'-deoxy-3'fluorothymidine (FLT) as a predictor of outcome in patients with locally advanced resectable rectal cancer: a pilot study

PURPOSE

This pilot study was performed to evaluate whether tumor uptake of (18)F-labeled 3'-deoxy-3'fluorothymidine (FLT), a proliferative radiotracer, at baseline and early during therapy, is predictive of outcome in locally advanced rectal cancer.

PROCEDURES

Fourteen patients underwent positron emission tomography (PET) with 2-deoxy-2-[(18)F]fluoro-D-glucose (FDG) and FLT before therapy and PET with FLT approximately 2 weeks after initiating neoadjuvant chemoradiotherapy. FLT and FDG uptake were evaluated qualitatively and by maximum standardized uptake value (SUV(max)). Tumor FLT and FDG uptake were correlated with disease-free survival (DFS).

RESULTS

Thirteen patients underwent surgery after therapy, one died before surgery with progressive disease. FDG-PET/computed tomography detected regional lymph node metastases in five and FLT-PET was positive in one. High pretherapy FDG uptake (SUV(max) ≥ 14.3), low during-therapy FLT uptake (SUV(max) < 2.2), and high percentage change in FLT uptake (≥60 %) were predictive of improved DFS (p < 0.05 for all three values).

CONCLUSION

Pretherapy FDG uptake, during-therapy FLT uptake, and percentage change in FLT uptake were equally predictive of DFS.

Predictive value of PET-CT for pathological response in stages II and III breast cancer patients following neoadjuvant chemotherapy with docetaxel

PURPOSE

To prospectively study the value of PET-CT with fluorine-18 fluorodeoxyglucose (FDG) to predict neoadjuvant chemotherapy (NAC) response of locoregional disease of stages II and III breast cancer patients.

MATERIAL AND METHODS

A written informed consent and approval were obtained from the Ethics Committee. PET-CT accuracy in the prediction of pathologic complete response (pCR) after NAC was studied in primary tumors and lymph node metastasis in 43 women (mean age: 50 years: range: 27-71 years) with histologically proven breast cancer between December 2009 and January 2011. PET-CT was performed at baseline and after NAC. SUV(max) percentage changes (ΔSUV(max)) were compared with pathology findings at surgery. Receiver-operator characteristic (ROC) analysis was used to discriminate between locoregional pCR and non-pCR. In patients not achieving pCR, it was investigated if ΔSUV(max) could accurately identify the residual cancer burden (RCB) classes: RCB-I (minimal residual disease (MRD)), RCB-II (moderate RD), and RCB-III (extensive RD).

RESULTS

pCR was obtained in 11 patients (25.6%). Residual disease was found in 32 patients (74.4%): 16 (37.2%) RCB-I, 15 (35.6%) RCB-II and 2 (4.7%) RCB-III. Sensitivity, specificity, and accuracy to predict pCR were 90.9%, 90.6%, and 90.7%, respectively. Specificity was 94.1% in the identification of a subset of patients who had either pCR or MRD.

CONCLUSION

Accuracy of ΔSUV(max) in the locoregional disease of stages II and III breast cancer patients after NAC is high for the identification of pCR cases. Its specificity is potentially sufficient to identify a subgroup of patients who could be managed with conservative surgery.

Fluorine-18 fluorodeoxyglucose positron emission tomography-computed tomography in monitoring the response of breast cancer to neoadjuvant chemotherapy: a meta-analysis

INTRODUCTION

To evaluate the diagnostic performance of fluorine-18 fluorodeoxyglucose positron emission tomography (FDG-PET) in monitoring the response of breast cancers to neoadjuvant chemotherapy.

METHODS

Articles published in medical and oncologic journals between January 2000 and June 2012 were identified by systematic MEDLINE, Cochrane Database for Systematic Reviews, and EMBASE, and by manual searches of the references listed in original and review articles. Quality of the included studies was assessed by using the quality assessment of diagnosis accuracy studies score tool. Meta-DiSc statistical software was used to calculate the summary sensitivity and specificity, positive predictive and negative predictive values, and the summary receiver operating characteristics curve (SROC).

RESULTS

Fifteen studies with 745 patients were included in the study after meeting the inclusion criteria. The pooled sensitivity and specificity of FDG-PET or PET/CT were 80.5% (95% CI, 75.9%-84.5%) and 78.8% (95% CI, 74.1%-83.0%), respectively, and the positive predictive and negative predictive values were 79.8% and 79.5%, respectively. After 1 and 2 courses of chemotherapy, the pooled sensitivity and false-positive rate were 78.2% (95% CI, 73.8%-82.5%) and 11.2%, respectively; and 82.4% (95% CI, 77.4%-86.1%) and 19.3%, respectively.

CONCLUSIONS

Analysis of the findings suggests that FDG-PET has moderately high sensitivity and specificity in early detection of responders from nonresponders, and can be applied in the evaluation of breast cancer response to neoadjuvant chemotherapy in patients with breast cancer.

Diagnostic and prognostic application of positron emission tomography in breast imaging: emerging uses and the role of PET in monitoring treatment response

Positron emission tomography (PET) is an imaging modality that using radiotracers, permits real-time dynamic monitoring of biologic processes such as cell metabolic behavior and proliferation, and has proven useful as a research tool for understanding tumor biology. While it does not have a well-defined role in breast cancer for the purposes of screening, diagnosis, or prognosis, emerging PET technologies and uses could expand the applications of PET in breast cancer. Positron emission mammography may provide an alternative adjunct imaging modality for the screening and diagnosis of high-risk patients unable to tolerate MRI. The development of radiotracers with the ability to measure hormonal activity could provide a non-invasive way to assess hormone receptor status and functionality. Finally, the role of PET technologies in monitoring early treatment response may prove particularly useful to research involving new therapeutic interventions.

Performance of FDG PET/CT in the clinical management of breast cancer

In this analysis, the role of metabolic imaging with fluorine 18 fluorodeoxyglucose (FDG) in breast cancer is reviewed. The analysis was limited to recent works by using state-of-the-art positron emission tomography (PET)/computed tomography (CT) technology. The strengths and limitations of FDG PET/CT are examined in various clinical settings, and the following questions are answered: Is FDG PET/CT useful to differentiate malignant from benign breast lesions? Can FDG PET/CT replace sentinel node biopsy for axillary staging? What is the role of FDG PET/CT in initial staging of inflammatory or locally advanced breast cancer? What is the role of FDG PET/CT in initial staging of clinical stage IIA and IIB and primary operable stage IIIA breast cancer? How does FDG PET/CT compare with conventional techniques in the restaging of cancer in patients who are suspected of having disease recurrence? What is the role of FDG PET/CT in the assessment of early response to neoadjuvant therapy and of response to therapy for metastatic disease? Some recommendations for clinical practice are given.

The role of FDG-PET-CT in the evaluation of primary systemic therapy in breast cancer: links between metabolic and pathological remission

Introduction: FDG-PET-CT is highly sensitive in detection of viable tumour tissue, giving an importance for that in oncological diagnostics. Aim: The authors analysed retrospectively the relationship between metabolic response and changes in Ki-67, a proliferation marker. Methods: Staging FDG-PET-CT scans (before and after therapy) SUVs (Standardized Uptake Value), and morphological changes in the primary tumour and axillary lymph node region were evaluated in 30 patients with breast cancer. Calculated ΔSUV were compared with Ki-67 proliferation marker (measured in biopsies and surgical specimens). Results: The decrease of SUV and size were significant in the primary tumour and the axillary lymph node region. Decrease of Ki-67 was significant. Significant correlation was found between Ki-67 and SUV before therapy, initial Ki-67 and ΔSUV, and ΔKi-67 and ΔSUV. Conclusions: The metabolic changes were more sensitive in the measurement of the therapeutic response than morphological remission, and they correlated well with the pathological response, in not standardized clinical conditions even. Orv. Hetil., 2012, 153, 1958–1964.

Usefulness of Combined Metabolic-Volumetric Indices of (18)F-FDG PET/CT for the Early Prediction of Neoadjuvant Chemotherapy Outcomes in Breast Cancer

PURPOSE

The purpose of this study was to investigate the usefulness of metabolic-volumetric indices of (18)F- fluorodeoxy-D-glucose ((18)F-FDG) positron emission tomography/computed tomography (PET/CT) for the evaluation of neoadjuvant chemotherapy outcomes in breast cancer.

METHODS

Twenty-four patients with locally advanced breast cancer were enrolled in the study. They underwent baseline (18)F-FDG PET/CT scan and received four or six cycles of neoadjuvant chemotherapy, interim (18)F-FDG PET/CT was done after second cycle of chemotherapy. Maximum standardized uptake value (SUVmax), metabolic tumor volume (MTV), and total lesion glycolysis (TLG) of the primary lesions were calculated. Reduction rates of these parameters were obtained between baseline and interim (18)F-FDG PET/CT. Chemotherapy outcomes were assessed using tumor size reduction rate and histological grading system (Miller and Payne system). Reduction rates of SUVmax, MTV, and TLG correlated with chemotherapy outcomes.

RESULTS

MTV and TLG reduction rates showed significant correlation with tumor size reduction rate (R = 0.68, P = 0.0004; R = 0.62, P = 0.002, respectively). However, SUVmax reduction rate showed no significant correlation. MTV and TLG reduction rates were significantly higher in responders than nonresponders, as determined by Miller and Payne system (P < 0.0007, P < 0.002). However, SUVmax reduction rate showed no significant difference. On ROC analysis, the area under the MTV and TLG curves was 0.886, and that of SUVmax was 0.743. Sensitivity, specificity, positive predictive value, and negative predictive value to predict histopathologic response were the same for MTV and TLG, and the values were 100 %, 85.7 %, 83.3 %, and 100 %, respectively (at the reduction rate of 93.2 % for MTV, and 95.8 % for TLG).

CONCLUSION

Changes of metabolic-volumetric indices successfully reflected the neoadjuvant chemotherapy outcomes. MTV and TLG could be robust indices in discriminating pathologic responder as SUVmax, after neoadjuvant chemotherapy.

18F-FDG PET/CT and PET for evaluation of pathological response to neoadjuvant chemotherapy in breast cancer: a meta-analysis

BACKGROUND

Neoadjuvant chemotherapy is increasingly the treatment for patients with inoperable breast cancer. Considering the side-effects of chemotherapy, there is a need for early evaluating response to neoadjuvant chemotherapy.

PURPOSE

To determinate the diagnostic performance of 18F-fluorodeoxyglucose position emission tomography/computed tomography (FDG PET/CT) and FDG PET for evaluating response to neoadjuvant chemotherapy in patients with breast cancer.

MATERIAL AND METHODS

"PubMed" (MEDLINE included) database, EMBASE, and Cochrane Database of Systematic Reviews were searched for relevant articles. We assessed the methodological quality of included study with Quality Assessment of Diagnosis Accuracy Studies (QUADAS) score tool, and used "Meta-DiSc" statistic software to obtain pooled estimates of sensitivity, specificity, diagnostic odds ratio (DOR), and summary receiver-operating characteristic (SROC) curve.

RESULTS

Seventeen studies (a total of 781 subjects) met the inclusion criteria. The pooled sensitivity was 0.840 (95% confidence interval [CI] 0.796-0.878). The pooled specificity was 0.713 (95% CI 0.667-0.756). For FDG PET/CT (10 studies included), the pooled sensitivity was 0.847 (95% CI 0.793-0.892), the pooled specificity was 0.661 (95% CI 0.598-0.720). The pooled likelihood ratio (LR+), negative likelihood ratio (LR-), and diagnostic odds ratio (DOR) were 2.835 (95% CI 1.640-4.900), 0.221 (95% CI 0.160-0.305), and 17.628 (95% CI 7.431-41.818). The area under the SROC curve (AUC) was 0.8934. For FDG PET (7 studies included), the pooled sensitivity and specificity were 0.826 (95% CI 0.741-0.892) and 0.789 (95% CI 0.719-0.849). The pooled LR + , LR-, and DOR were 3.601 (95% CI 2.601-4.986), 0.242 (95% CI 0.157-0.374), and 13.641 (95% CI 7.433-25.030). The AUC was 0.8764.

CONCLUSION

Our results indicate that FDG PET/CT and PET have reasonable sensitivity in evaluating response to neoadjuvant chemotherapy in breast cancer; however, the specificity is relative low. The combination of other imaging methods with FDG PET/CT or PET is recommended.

FDG-PET/CT for the early prediction of histopathological complete response to neoadjuvant chemotherapy in breast cancer patients: initial results

BACKGROUND

Up to about one-quarter of patients treated with neoadjuvant chemotherapy do not adequately respond to the given treatment. By a differentiation between responders and non-responders ineffective toxic therapies can be prevented.

PURPOSE

To retrospectively test if FDG-PET/CT is able to early differentiate between breast cancer lesions with pathological complete response (pCR) and lesions without pathological complete response (npCR) after two cycles of neoadjuvant chemotherapy (NACT).

MATERIAL AND METHODS

In this retrospective study 26 breast cancer patients (mean age, 46.9 years ± 9.9 years) underwent a pre-therapeutic FDG-PET/CT scan and a subsequent FDG-PET/CT after the second cycle of NACT. Histopathology of resected specimen served as the reference standard. Maximum standardized uptake values (SUVmax) of cancer lesions before and after the second cycle of NACT were measured. Two evaluation algorithms were used: (a) pCR: Sinn Score 3 and 4, npCR: Sinn Score 0-2; (b) pCR: Sinn Score 4, npCR: Sinn Score 0-3. The absolute and relative decline of the SUVmax (ΔSUVmax, ΔSUVmax(%))was calculated. Differences of the SUVmax as well as of the SUVmax decline between pCR lesions and npCR lesions were tested for statistical significance P < 0.05. To identify the optimal cut-off value of ΔSUVmax(%) to differentiate between pCR lesions and npCR lesions a receiver-operating curve (ROC) analysis was performed.

RESULTS

Using evaluation algorithm A the ΔSUVmax was 13.5 (pCR group) and 3.9 (npCR group) (P = 0.006); the ΔSUVmax(%) was 79% and 47%, respectively (P = 0.001). On ROC analysis an optimal cut-off ΔSUVmax(%) of 66% was found. Using evaluation algorithm B the ΔSUVmax was 17.5 (pCR group) and 4.9 (npCR group) (P = 0.013); the ΔSUVmax(%) was 89% and 51%, respectively (P = 0.003). On ROC analysis an optimal cut-off ΔSUVmax(%) of 88% was found.

CONCLUSION

FDG-PET/CT may be able to early differentiate between pCR and npCR of primary breast cancer lesions after two cycles of NACT.

3D tumour spheroids as a model to assess the suitability of [18F]FDG-PET as an early indicator of response to PI3K inhibition

BACKGROUND

[18F] Fluorodeoxyglucose Positron Emission Tomography ([18F]FDG-PET) is widely used to monitor response to therapy in the clinic and has, more recently, been proposed as an early marker of long term response. This relies on the assumption that a change in glucose consumption parallels a reduction in viability and long term growth potential. However, cells may utilise substrates other than glucose and as many therapeutics interfere with glucose metabolism directly, it is entirely plausible that a positive [18F]FDG-PET response may be unrelated to long term growth. Furthermore, changes in metabolism and proliferation may take place on different temporal scales, thus restricting the time window in which [18F]FDG-PET is predictive. The PI3K oncogenic signalling pathway is a master regulator of multiple cellular processes including glucose metabolism, proliferation and cell survival. Inhibition of PI3K has been shown to reduce [18F]FDG uptake in several tumour types but the relative influence of this pathway on glucose metabolism and proliferation is not fully established.

AIM

We proposed to (i) assess the suitability of [18F]FDG as a tracer for measuring response to PI3K inhibition and (ii) determine the optimum imaging schedule, in vitro. We used multicellular tumour spheroids, an excellent 3D in vitro model of avascular tumours, to investigate the effects of the PI3K inhibitors, NVP-BKM120 and NVP-BEZ235, on [18F]FDG uptake and its relation to 3D growth.

METHODS

Spheroids were prepared from two cell lines with a constitutively active PI3K/Akt pathway, EMT6 (highly proliferative mouse mammary) and FaDu (moderately proliferate human nasopharyngeal). Treatment consisted of a 24h exposure to either inhibitor, and growth was monitored over the following 7 days. To mimic potential imaging regimens with [18F]FDG-PET, average [18F]FDG uptake per viable cell was measured (a) directly following the 24h exposure, (b) following an additional 24h recovery period, or (c) following a 48 h exposure.

RESULTS

Growth was restricted significantly (p<0.0001) in a dose-dependent fashion in spheroids from both cell lines treated with either inhibitor. In the highly proliferative cell line EMT6, [18F]FDG uptake was significantly reduced at all concentrations of inhibitor. For the moderately proliferative cell line FaDu, [18F]FDG was affected in a dose-dependent fashion, but to lesser degree. To assess the predictivity of [18F]FDG uptake for long term growth restriction, Pearson correlation coefficients were calculated for each imaging regimen. These indicated that the optimal imaging schedules differed between cell lines.

CONCLUSION

This study suggests that [18F]FDG may be a suitable marker of response to PI3K inhibition in the cell lines that we have studied. Our data support the hypothesis that imaging schedules should be optimised on a tumour type-specific basis.

Neoadjuvant chemotherapy in breast cancer: prediction of pathologic response with PET/CT and dynamic contrast-enhanced MR imaging--prospective assessment

PURPOSE

To clarify whether fluorine 18 ((18)F) fluorodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography (CT) and dynamic contrast-enhanced (DCE) magnetic resonance (MR) imaging performed after two cycles of neoadjuvant chemotherapy (NAC) can be used to predict pathologic response in breast cancer.

MATERIALS AND METHODS

Institutional human research committee approval and written informed consent were obtained. Accuracy after two cycles of NAC for predicting pathologic complete response (pCR) was examined in 142 women (mean age, 57 years: range, 43-72 years) with histologically proved breast cancer between December 2005 and February 2009. Quantitative PET/CT and DCE MR imaging were performed at baseline and after two cycles of NAC. Parameters of PET/CT and of blood flow and microvascular permeability at DCE MR were compared with pathologic response. Patients were also evaluated after NAC by using Response Evaluation Criteria in Solid Tumors (RECIST) 1.1 based on DCE MR measurements and European Organization for Research and Treatment of Cancer (EORTC) criteria and PET Response Criteria in Solid Tumors (PERCIST) 1.0 based on PET/CT measurements. Multiple logistic regression analyses were performed to examine continuous variables at PET/CT and DCE MR to predict pCR, and diagnostic accuracies were compared with the McNemar test.

RESULTS

Significant decrease from baseline of all parameters at PET/CT and DCE MR was observed after NAC. Therapeutic response was obtained in 24 patients (17%) with pCR and 118 (83%) without pCR. Sensitivity, specificity, and accuracy to predict pCR were 45.5%, 85.5%, and 82.4%, respectively, with RECIST and 70.4%, 95.7%, and 90.8%, respectively, with EORTC and PERCIST. Multiple logistic regression revealed three significant independent predictors of pCR: percentage maximum standardized uptake value (%SUV(max)) (odds ratio [OR], 1.22; 95% confidence interval [CI]: 1.11, 1.34; P < .0001), percentage rate constant (%k(ep)) (OR, 1.07; CI: 1.03, 1.12; P = .002), and percentage area under the time-intensity curve over 90 seconds (%AUC(90)) (OR, 1.04; CI: 1.01, 1.07; P = .048). When diagnostic accuracies are compared, PET/CT is superior to DCE MR for the prediction of pCR (%SUV(max) [90.1%] vs %κ(ep) [83.8%] or %AUC(90) [76.8%]; P < .05).

CONCLUSION

The sensitivities of %SUV(max) (66.7%), %k(ep) (51.7%), and %AUC(90) (50.0%) at (18)F-FDG PET/CT and DCE MR after two cycles of NAC are not acceptable, but the specificities (96.4%, 92.0%, and 95.2%, respectively) are high for stratification of pCR cases in breast cancer.

Defining the role of PET-CT in staging early breast cancer

INTRODUCTION

Currently, there is a lack of data on the role of combined positron emission tomography-computed tomography (PET-CT) in the staging of early invasive primary breast cancer. We therefore evaluated the role of (18)F-fluorodeoxyglucose ((18)F-FDG)-PET-CT in this patient population.

METHODS

We prospectively recruited 70 consecutive patients (69 women, one man; mean age, 61.9 ± 8.1 years) with early primary breast cancer for staging with (18)F-FDG-PET-CT. All PET-CT images were interpreted by two readers (independently of each other). A third reader adjudicated any discrepancies. All readers had ≥5 years of specific experience. Ethics board approval and informed consent were obtained.

RESULTS

The mean clinical follow-up was 22.7 ± 12.6 months. The primary tumor was identified with PET-CT in 64 of 70 patients. Of the unidentified lesions, surgical pathology revealed two intraductal carcinomas, one invasive tubular carcinoma, and three invasive lobular carcinomas. Undiagnosed multifocal breast disease was shown in seven of 70 patients. PET-CT identified avid axillary lymph nodes in 19 of 70 patients, compared with 24 of 70 confirmed during surgery. There were four patients who were axillary node positive on PET but had no axillary disease at surgery. Five patients were reported with avid metastases. Two of those patients were treated for metastatic disease (nodal, lung, and liver in one and bone metastases in the other) following further imaging and clinical assessment. In the other three patients, lesions (lung, n = 1; pleural, n = 1; paratrachael node, n = 1) were subsequently diagnosed as benign lesions.

CONCLUSION

Integrated (18)F-FDG-PET-CT may have a role in staging patients presenting with early breast cancer.

Positron emission tomography and neoadjuvant therapy of breast cancer

The increasing use of neoadjuvant therapy for breast cancer has led to the development of early surrogate markers of response. Positron emission tomography (PET) allows noninvasive study of fundamental biologic processes in the tumor; furthermore, PET provides various markers to assess tumor response early in the course of therapy. Numerous studies have shown that changes in tumor glucose metabolism during therapy are significantly correlated with final response and patient outcome. Moreover, new PET tracers that are currently being developed or under evaluation, providing specific information on tumor characteristics or receptor expression, will assist the development of new targeted anticancer agents.