Prediction of Response to Preoperative Chemotherapy in Gastric Carcinoma by Metabolic Imaging: Results of a Prospective Trial

Positron emission tomography as an imaging biomarker

Positron emission tomography (PET) allows noninvasive, quantitative studies of various biologic processes in the tumor tissue. By using PET, investigators can study the pharmacokinetics of anticancer drugs, identify various therapeutic targets and monitor the inhibition of these targets during therapy. Furthermore, PET provides various markers to assess tumor response early in the course of therapy. A significant number of studies have now shown that changes in tumor glucose utilization during the first weeks of chemotherapy are significantly correlated with patient outcome. These data suggest that PET may be used as a sensitive test to assess the activity of new cytotoxic agents in phase II studies. Furthermore, early identification of nonresponding tumors provides the opportunity to adjust treatment regimens according to the individual chemosensitivity of the tumor tissue. However, further prospective and randomized validation of PET is still required before PET controlled chemotherapy can be used in clinical practice.

High fluorodeoxyglucose uptake on positron emission tomography in patients with advanced non-small cell lung cancer on platinum-based combination chemotherapy

PURPOSE

To evaluate response and survival for platinum-based combination chemotherapy in chemonaive patients with non-small cell lung cancer (NSCLC) according to pretreatment standardized uptake values (SUV) by fluorodeoxyglucose positron emission tomography.

EXPERIMENTAL DESIGN

Patients with advanced NSCLC who had not previously received chemotherapy were eligible. Response rates and survivals were analyzed according to maximal SUVs [low (7.5), where 7.5 was the median value] before the first cycle of chemotherapy.

RESULTS

Eighty-five consecutive patients were included in the retrospective study. Patients with high SUV tumors exhibited significantly higher response rates (34.1% for low SUVs versus 61.0% for high SUVs; P = 0.013). Other factors, including sex, age, histology, performance status, number of involved organs, regimens used, and disease stage, did not affect response. However, high SUVs were related with a shorter response duration (279 days for low SUVs versus 141 days for high SUVs; P = 0.003) and time to progression (282 days for low SUVs versus 169 days for high SUVs; P = 0.015). Overall survival was unaffected by maximal SUVs (623 days for low SUVs versus 464 days for high SUVs; P = 0.431).

CONCLUSIONS

Patients having NSCLC with high maximal SUVs showed a better response to platinum-based combination chemotherapy but had a shorter time to progression. Tumor glucose metabolism, as determined by SUVs on fluorodeoxyglucose positron emission tomography, was found to discriminate NSCLC subsets with different clinical and biological features.

Clinical molecular imaging with positron emission tomography

Molecular imaging allows for the in vivo evaluation of targeted molecules and biological processes in man. Positron emission tomography (PET) is a highly sensitive and quantitative molecular imaging modality, whose utility in clinical and experimental medicine is increasing by the day. In this article, the principles of PET and its currently accepted applications in oncology, such as cancer staging, treatment response assessment and as a prognostic marker are reviewed. Further, the evolving role of PET in areas of oncology such as radiotherapy treatment planning, anti-cancer drug development and the evaluation of patho-physiological processes which drive a cell into neoplastic activity is discussed.

Monitoring chemotherapy and radiotherapy of solid tumors

PET imaging with the glucose analog fluorodeoxyglucose (FDG-PET) has been evaluated in numerous studies to monitor tumor response in patients undergoing chemo- and radiotherapy. The clinical value of FDG-PET for differentiation of residual or recurrent viable tumor and therapy-induced fibrosis or scar tissue has been documented for various solid tumors. Furthermore, there are now several reports suggesting that quantitative assessment of therapy-induced changes in tumor FDG uptake may allow prediction of tumor response and patient outcome very early in the course of therapy. In nonresponding patients, treatment may be adjusted according to the individual chemo- and radiosensitivity of the tumor tissue. Since the number of alternative treatments for solid tumors (e.g., second-line chemotherapy agents, protein kinase, or angiogenesis inhibitors) is continuously increasing, early prediction of tumor response to chemotherapy and radiotherapy by FDG-PET has enormous potential to "personalize" treatment and to reduce the side-effects and costs of ineffective therapy.

Adenocarcinomas of Esophagogastric Junction: Multi–Detector Row CT to Evaluate Early Response to Neoadjuvant Chemotherapy

PURPOSE

To prospectively evaluate multi-detector row computed tomography (CT) in the assessment of early response during neoadjuvant chemotherapy for adenocarcinoma of the esophagogastric junction (AEG).

MATERIALS AND METHODS

The study protocol was approved by the local ethics committee. Written informed consent was obtained from all patients. Thirty-one patients with an AEG (stage T3 N0/1 M0 or T4 N0/1 M0) were examined with multi-detector row CT before and 2 weeks after the initiation of chemotherapy. There were seven women and 24 men with a mean age of 62 years +/- 8.1 (standard deviation). The maximal transverse tumor diameter was measured and tumor volumetry was performed by three independent readers. The resulting changes were correlated with the histopathologic grade of regression in 21 patients. The differentiation of responders from nonresponders was assessed with receiver operating characteristic analysis in these 21 patients. Interobserver variability was determined in all 31 patients with the Spearman rank correlation. Survival without disease progression was estimated in all patients according to the Kaplan-Meier method. Statistical comparisons between different groups of patients were performed with the log-rank test.

RESULTS

The interobserver variability for the diameter measurements (R = 0.13-0.20) was higher than that for the volumetric measurements (R = 0.70-0.82). The correlation of histopathologic grades of regression with changes in diameter was not statistically significant for the three readers, whereas the correlation of volume changes with histopathologic grades of regression was statistically significant for two of the three readers (P = .01, .05, and .08). Results of receiver operating characteristic analysis revealed an optimal cutoff level for tumor volumetry at a reduction of volume of 14.8%, which resulted in a sensitivity of 100% (six of six patients) and a specificity of 53% (eight of 15 patients). Although the probability of progression was higher in the nonresponder group than in the responder group (61% vs 40%, respectively), the differences were not statistically significant.

CONCLUSION

Tumor volumetry based on multi-detector row CT can help predict early response to treatment 2 weeks after the initiation of neoadjuvant chemotherapy in patients with AEG; however, the classic approach of tumor diameter measurement failed to show significant correlation with histopathologic tumor regression.

Use of positron emission tomography to target prostate cancer gene therapy by oncolytic herpes simplex virus

Herpes simplex virus (HSV) oncolytic gene therapy is a promising treatment modality against cancer. We have demonstrated that androgen-induced cellular changes enhance oncolytic viral replication and improve efficacy in the treatment of androgen-dependent prostate cancer cell line. Imaging of changes in 2-deoxy-2-[F-18]fluoro-D-glucose (FDG) uptake by positron emission tomography (PET) is a sensitive method of detecting altered cellular metabolism involved in cancer therapy. We therefore hypothesized that FDG-PET can predict tumor response to oncolytic HSV therapy. In this study, androgen increased cell kill (74%) in vitro and enhanced viral yield (2.4-fold) in vivo following HSV therapy. This enhanced efficacy was predicted by high FDG accumulation in intact animals compared to low FDG uptake following orchiectomy (p = 0.002). This proof-of-concept study provides the mechanistic basis for selecting patients for targeted oncolytic viral therapy by means of a noninvasive molecular imaging method in the treatment of prostate cancer.

Selection of patients with gastric adenocarcinoma for laparoscopic staging

BACKGROUND

To refine selection criteria for laparoscopic staging of gastric adenocarcinoma, preoperatively available clinical and radiologic factors that may predict the risk of M1 disease were investigated.

METHODS

During 1993-2002, laparoscopy was performed if patients had minimal symptoms and there was no definite M1 disease at computed tomography (CT) scanning. High-quality, spiral, CT scans were reviewed in detail for 65 recent patients.

RESULTS

Laparoscopy was conducted for 657 patients and M1 was detected in 31%. M1 was significantly more prevalent with tumor location at the gastroesophageal junction (GEJ; M1 in 42%) or whole stomach (66%), poor differentiation (36%) or age < or = 70 years (34%). On spiral CT scan, lymphadenopathy > or = 1 cm (49%) or T3/T4 tumors (63%) were associated with significantly higher prevalence of M1. On multivariate analyses, only tumor location (GEJ or whole stomach) and lymphadenopathy were independently significant and M1 was not detected in any patient with neither risk factor.

CONCLUSIONS

With spiral CT staging, laparoscopy may be avoided if the primary tumor is not at the GEJ or whole stomach and there is no lymphadenopathy.

CT and PET in stomach cancer: preoperative staging and monitoring of response to therapy

Stomach cancer is one of the leading causes of cancer mortality worldwide. Complete resection of a gastric tumor and adjacent lymph nodes represents the only potentially curative intervention. Computed tomography (CT) has remained the modality of choice for the preoperative staging of gastric cancer and for follow-up. A recently developed advanced CT technique that makes use of thin sections, optimal contrast material enhancement, and multiplanar reformation allows more accurate staging. However, CT may be limited in the identification of nonenlarged lymph node metastasis, peritoneal dissemination, and small hematogenous metastasis. Positron emission tomography (PET) with 2-[fluorine-18]fluoro-2-deoxy-d-glucose (FDG) has been recognized as a useful diagnostic technique in clinical oncology. FDG PET allows scanning of a larger volume than is possible with CT. Although FDG PET is not an appropriate first-line diagnostic procedure in the detection of stomach cancer and is not helpful in tumor staging, it may play a valuable role in the detection of distant metastases, such as those of the liver, lungs, adrenal glands, ovaries, and skeleton. FDG PET may also be helpful in the follow-up of patients undergoing chemotherapy, as it allows the identification of early response to treatment. Further studies are needed to determine the efficacy of FDG PET in the detection of local nodal metastases and peritoneal dissemination. Nevertheless, the combined use of CT and PET can be helpful in the preoperative staging of stomach cancer and in the therapeutic monitoring of affected patients.

[18F]Fluorodeoxyglucose positron emission tomography predicts outcome for Ewing sarcoma family of tumors

PURPOSE

Response to neoadjuvant chemotherapy is a significant prognostic factor for the Ewing sarcoma family of tumors (ESFTs). [18F]fluorodeoxyglucose (FDG) positron emission tomography (PET) is a noninvasive imaging modality that accurately predicts histopathologic response in several malignancies. To determine the prognostic value of FDG PET response for progression-free survival (PFS) in ESFTs, we reviewed the University of Washington Medical Center experience.

PATIENTS AND METHODS

Thirty-six patients with ESFTs were evaluated by FDG PET. All patients received neoadjuvant and adjuvant chemotherapy. FDG PET standard uptake values before (SUV1) and after (SUV2) chemotherapy were analyzed and correlated with chemotherapy response, as assessed by histopathology in surgically excised tumors. Thirty-four patients had both SUV1 and SUV2.

RESULTS

The mean SUV1, SUV2, and ratio of SUV2 to SUV1 (SUV2:1) were 7.9 (range, 2.3 to 32.8), 2.1 (range, 0 to 4.3), and 0.36 (range, 0.00 to 1.00), respectively. Good FDG PET response was defined as SUV2 less than 2.5 or SUV2:1 < or = 0.5. FDG PET response by SUV2 or SUV2:1 was concordant with histologic response in 68% and 69% of patients, respectively. SUV2 was associated with outcome (4-year PFS 72% for SUV2 < 2.5 v 27% for SUV2 > or = 2.5, P = .01 for all patients; 80% for SUV2 < 2.5 v 33% for SUV2 > or = 2.5, P = .036 for localized at diagnosis patients). SUV2:1 < or = 0.5 was not predictive of PFS.

CONCLUSION

FDG PET imaging of ESFTs correlates with histologic response to neoadjuvant chemotherapy. SUV2 less than 2.5 is predictive of PFS independent of initial disease stage.

Gastrointestinal malignancies evaluated with (18)F-fluoro-2-deoxyglucose positron emission tomography

(18)F-fluoro-2-deoxyglucose positron emission tomography has demonstrated high accuracy in the staging and evaluation of colorectal and esophageal carcinomas. FDG PET is demonstrating increasing utility in a number of other gastrointestinal tumours and clinical scenarios. The established clinical indications for its use, the diagnostic accuracy, and limitations will be reviewed. Data on the emerging indications and limitations for pancreatic, hepatocellular, and gastric carcinomas, as well as gastrointestinal stromal tumours, cholangiocarcinoma, and carcinoma of unknown primary will also be briefly discussed. The use of combined PET-CT is demonstrating further improvements in diagnostic accuracy.

Quantifying the Effect of IV Contrast Media on Integrated PET/CT: Clinical Evaluation

OBJECTIVES

The use of IV contrast media in PET/CT can result in an overestimation of PET attenuation factors that potentially can affect interpretation. The objective of this study was to quantify the effect of IV contrast media in PET/CT and assess its impact on patients with intrathoracic malignancies.

MATERIALS AND METHODS

Nine patients had CTs performed with and without IV contrast media followed by (18)F-FDG PET. PET images were reconstructed using contrast-enhanced and unenhanced CT. To quantify the effect of contrast media on standardized uptake values (SUV), similar regions of interest (ROIs) were drawn on the subclavian vein, heart, liver, spleen, and site of malignancy on both CT and corresponding reconstructed PET images, and the mean and maximum values were compared. In addition, two physicians blinded to the imaging parameters that were used evaluated the reconstructed PET images to assess whether IV contrast media had an effect on clinical interpretation.

RESULTS

For all patient studies, the subclavian vein region on the ipsilateral side of contrast media administration had the highest increase in CT numbers with a corresponding average SUV(max) increase of 27.1%. Similarly, ROIs of the heart and at the site of malignancy showed an increase in the maximum attenuation value with a corresponding average SUV(max) increase of 16.7% and 8.4%, respectively. Other locations had relatively small attenuation value differences with a correspondingly negligible SUV variation.

CONCLUSION

Although there is a significant increase in SUV in regions of high-contrast concentration when contrast-enhanced CT is used for attenuation correction, this increase is clinically insignificant. Accordingly, in PET/CT, IV contrast-enhanced CT can be used in combination with the PET to evaluate patients with cancer.

PET in abdominal pathology: advantages and limitations

New oncologic procedures are currently more focused on the biological features of tumors. The ideal objective is the administration of personalized effective treatments for each patient that affects not just the location and spread of disease but also special metabolic characteristics of tumoral cells. Radiologic diagnostic methods are extremely important in the management of the patient for staging, restaging, and evaluation of treatment response, and clinicians are avid for some additional functional and metabolic information. Further, they need more dynamic methods for follow-up. Nuclear Medicine and positron emission tomography (PET) in many cases can meet this requirement, although it is not perfect, at least at the present time. Currently 2-((18)F)fluoro-2-desoxi-D: -glucose positron emission tomography is being widely used for oncologic purposes. Its information can be very useful in abdominal diseases and must be taken into account with the results of radiologic imaging. Thus, many changes in the choice of treatment are seen. However, it is very important to know that sometimes there is a lack of specificity that has to be considered.

Thethymidylate synthase tandem repeat promoter polymorphism: A predictor for tumor-related survival in neoadjuvant treated locally advanced gastric cancer

We evaluated DNA polymorphisms in the thymidylate synthase (TS) and 5,10-methylene-tetrahydrofolate reductase (MTHFR) genes for an association with response and survival in locally advanced gastric cancer treated with 5-FU based preoperative chemotherapy (CTx). DNA of 238 patients (CTx-group: total n = 135, completely resected (R0) n = 102; without CTx: R0 n = 103) was isolated from blood or from nontumorous tissues. In the CTx-group, genotyping of the tandem repeat and the G/C polymorphism in the triple repeat in the promoter region of the TS gene and of the C677T polymorphism of the MTHFR gene was performed. None of the TS or MTHFR genotypes were associated with histopathological response and only the TS tandem repeat polymorphism was significantly related to survival (all patients n = 135, p = 0.002; R0 resected patients n = 102, p = 0.007; log-rank test). Multivariate analysis revealed ypN (p < 0.001) and the TS tandem repeat polymorphism as independent prognostic factors in the CTx-R0-group (p = 0.003). Analyzing the prognostic significance of the TS polymorphisms in the R0-group without CTx, TS genotypes were not significantly associated with survival. Comparing survival between R0 patients with and without CTx in the respective TS genotype groups of the tandem repeat polymorphism, a significant survival benefit for the patients with CTx was found for the 2rpt/2rpt (n = 49; p = 0.002) and 2rpt/3rpt genotypes (n = 99; p = 0.004), but not for the 3rpt/3rpt genotype (n = 57; p = 0.93). Patients' survival after CTx was associated with the TS tandem repeat polymorphism. CTx did not improve survival of patients with the 3rpt/3rpt genotype. Thus, a different therapy might be more appropriate for these patients.

Staging in oesophageal cancer

Accurate staging defines groups for stage-specific treatment, minimising inappropriate treatment. Application of dedicated staging methods - including 16-64 multidetector computed tomography (CT), endoscopic ultrasonography with fine-needle aspiration (EUS-FNA) and positron emission tomography (PET) - results in better staging of oesophageal cancer. PET as a metabolic imaging technique that is usually applied after (or recently in combination with) CT (PET/CT) improves the accuracy of non-invasive staging, especially in locally advanced oesophageal cancer patients. Whether EUS-FNA or PET/CT should be performed as a first diagnostic step is still a matter of debate. Fluoro-2-deoxyglucose (FDG) PET is also promising tool in assessing neoadjuvant treatment response. Application of these dedicated staging methods has a learning curve, suggesting a prominent role for centralisation.

Multimodal treatment of gastrointestinal tract tumors: consequences for surgery

Formerly an exclusive business of surgery, gastrointestinal (GI) tumors are nowadays increasingly approached with multimodal strategies. Neoadjuvant concepts have had a particularly far-reaching impact on surgery and have contributed to improved survival. Modern pre-treatment staging and risk assessment provide the basis for decision on one of three general treatment concepts (1) Early cancers, confined to the mucosal/submucosal layers, are approached with primary surgery, without prior antineoplastic therapy. (2) Systemically metastasized tumors receive merely palliative treatment. (3) Locally advanced cancers are increasingly approached with neoadjuvant strategies. The benefit from these preoperative protocols is proven for diverse entities, but is evidently confined to a specific subgroup patients, i.e., the responders to neoadjuvant treatment. These are the ones benefiting most from subsequent surgical resection, which is required to ensure complete removal of the residual tumor tissue, as complete tumor regression occurs very rarely and cannot be proven without a specimen. The fact that responders will benefit and non-responders will not benefit or will even deteriorate during the neoadjuvant treatment makes early response prediction most demanding. An amazing new approach is the use of position emission tomography with fluro-desoxyglucose (FDG-PET) to assess the "metabolic response," which is possible as early as 14 days after initiation of the neoadjuvant protocol. This strategy offers the chance for modulating the surgical approach in accord i.e., with such metrobolic response termination of the protocol and proceeding to resection in the case of nonresponse. The future of GI cancer surgery is multimodal therapy in a response-based fashion and requires reponse-based trials for further evaluation.

Prediction of response to neoadjuvant chemotherapy by sequential F-18-fluorodeoxyglucose positron emission tomography in patients with advanced-stage ovarian cancer

PURPOSE

The aim of this study was to evaluate sequential F-18-fluorodeoxyglucose positron emission tomography (FDG-PET) to predict patient outcome after the first and third cycle of neoadjuvant chemotherapy in advanced-stage (International Federation of Gynecology and Obstetrics stages IIIC and IV) ovarian cancer.

PATIENTS AND METHODS

Thirty-three patients received three cycles of carboplatin-based chemotherapy, followed by cytoreductive surgery. Quantitative FDG-PET of the abdomen and pelvis was acquired before treatment and after the first and third cycle of chemotherapy. Changes in tumoral FDG uptake, expressed as standardized uptake values (SUV), were compared with clinical and histopathologic response; overall survival served as a reference.

RESULTS

A significant correlation was observed between FDG-PET metabolic response after the first (P = .008) and third (P = .005) cycle of chemotherapy and overall survival. By using a threshold for decrease in SUV from baseline of 20% after the first cycle, median overall survival was 38.3 months in metabolic responders compared with 23.1 months in metabolic nonresponders. At a threshold of 55% decrease in SUV after the third cycle median overall survival was 38.9 months in metabolic responders compared with 19.7 months in nonresponders. There was no correlation between clinical response criteria (P = .7) or CA125 response criteria (P = .5) and overall survival. There was only a weak correlation (P = .09) between histopathologic response criteria and overall survival.

CONCLUSION

Sequential FDG-PET predicted patient outcome as early as after the first cycle of neoadjuvant chemotherapy and was more accurate than clinical or histopathologic response criteria including changes in tumor marker CA125. FDG-PET appears to be a promising tool for early prediction of response to chemotherapy.

Progress and promise of FDG-PET imaging for cancer patient management and oncologic drug development

2-[(18)F]Fluoro-2-deoxyglucose positron emission tomography (FDG-PET) assesses a fundamental property of neoplasia, the Warburg effect. This molecular imaging technique offers a complementary approach to anatomic imaging that is more sensitive and specific in certain cancers. FDG-PET has been widely applied in oncology primarily as a staging and restaging tool that can guide patient care. However, because it accurately detects recurrent or residual disease, FDG-PET also has significant potential for assessing therapy response. In this regard, it can improve patient management by identifying responders early, before tumor size is reduced; nonresponders could discontinue futile therapy. Moreover, a reduction in the FDG-PET signal within days or weeks of initiating therapy (e.g., in lymphoma, non-small cell lung, and esophageal cancer) significantly correlates with prolonged survival and other clinical end points now used in drug approvals. These findings suggest that FDG-PET could facilitate drug development as an early surrogate of clinical benefit. This article reviews the scientific basis of FDG-PET and its development and application as a valuable oncology imaging tool. Its potential to facilitate drug development in seven oncologic settings (lung, lymphoma, breast, prostate, sarcoma, colorectal, and ovary) is addressed. Recommendations include initial validation against approved therapies, retrospective analyses to define the magnitude of change indicative of response, further prospective validation as a surrogate of clinical benefit, and application as a phase II/III trial end point to accelerate evaluation and approval of novel regimens and therapies.

Combined GADD45A and thymidine phosphorylase expression levels predict response and survival of neoadjuvant-treated gastric cancer patients

PURPOSE

We evaluated the expression of seven therapy-related genes to predict the clinical outcome of advanced gastric cancer patients treated with a neoadjuvant chemotherapeutic protocol.

EXPERIMENTAL DESIGN

Pretherapeutic, formalin-fixed, and paraffin-embedded biopsies of 61 patients, who received a 5-fluorouracil (5-FU)- and cisplatin-based chemotherapy were studied. The expressions of the 5-FU-related genes TS, DPD, and TP and of the cisplatin-related genes ERCC1, ERCC4, KU80, and GADD45A were analyzed by quantitative real-time PCR. The expression levels of single genes and of various combinations were tested for an association with response and overall survival.

RESULTS

High DPD levels were more frequently found in nonresponding patients and were associated with worse survival. GADD45A and TP levels showed weak associations with response, but GADD45A expression correlated with survival. There was no association with response for TS expression, but tumors with a high TS level were associated with worse survival. The combination of GADD45A and TP revealed the strongest predictive effect. High expression values of TP and/or GADD45A were exclusively found in nonresponding patients (P = 0.002) and were associated with a significantly poorer survival (P = 0.04).

CONCLUSIONS

Combined gene expression levels of TP and GADD45A represent a new variable to predict the clinical outcome after neoadjuvant chemotherapy in gastric cancer. The association of DPD expression with response and survival underlines a predominant role of DPD to predict 5-FU sensitivity. The association of TS expression levels with survival but not with response suggests an importance of this gene for tumor progression.

Utility of PET, CT, and EUS to identify pathologic responders in esophageal cancer

BACKGROUND

This study evaluates the utility of positron emission tomography (PET), endoscopic ultrasonography (EUS), and computed tomographic (CT) scans to predict pathologic response and survival following preoperative chemoradiation (CRT) in esophageal cancer.

METHODS

One hundred three sequential patients with locoregionally advanced esophageal cancer, who were treated with CRT and esophageal resection between May 2001 and November 2003 at the University of Texas M.D. Anderson Cancer Center, were retrospectively reviewed. PET, EUS, and CT were performed before (pre) or after (post) CRT and before surgical resection. PET standardized uptake value (SUV) was defined as maximal uptake in primary tumor.

RESULTS

Most patients were male (91 [88%]) with adenocarcinoma (90 [87%]). Pretreatment clinical stages were: IIA (42 [41%]), IIB (5 [5%]), III (50 [49%]), and IVA (6 [6%]). At the time of surgery, 58 patients (56%) had a pathologic response to CRT (< or =10% viable cells). Post-CRT measurements that correlated with pathologic response were: CT esophageal wall thickness (13.3 vs 15.3 mm, p = 0.04), EUS mass size (0.7 vs 1.7 cm, p = 0.01) and PET SUV (3.1 vs 5.8, p = 0.01). Post-CRT PET SUV equal to or greater than 4 had the highest accuracy for pathologic response (76%). Univariate and multivariate Cox regression analysis demonstrated that a post-CRT PET SUV equal to or greater than 4 was an independent predictor of survival (HR, 3.5, p = 0.04).

CONCLUSIONS

The FDG-PET SUV is the most accurate noninvasive test to predict long-term survival after preoperative CRT and before surgical resection. Post-CRT FDG-PET cannot, however, rule out residual microscopic disease so esophagectomy should remain a therapeutic option even if the post-CRT imaging modalities are normal.

Early restaging whole-body 18F-FDG PET during induction chemotherapy predicts clinical outcome in patients with locoregionally advanced nasopharyngeal carcinoma

PURPOSE

This study was undertaken to evaluate the utility of whole-body (18)F-FDG PET in monitoring therapeutic effect during induction chemotherapy (IC) and in predicting prognosis in patients with locoregionally advanced nasopharyngeal carcinoma (NPC).

METHODS

Fifty patients who had histologically proven, locoregionally advanced NPC without distant metastasis and had received IC were recruited in this study. The study cohort consisted of 19 females and 31 males (age 17-72 years, mean 45.9+/-11.9). Whole-body (18)F-FDG PET was performed in each patient after completion of one (33 patients) or two (17 patients) courses of IC. Each patient was restaged on the basis of the (18)F-FDG PET results. Patients who were downstaged to stage I or II were classified as major responders; the rest were classified as non-major responders.

RESULTS

Only 1 of the 23 major responders subsequently developed local recurrence. At the time of data analysis, all major responders were alive; by contrast, of the 27 non-major responders, 15 had locoregional recurrence or distant metastasis and nine had died (seven of NPC and two of treatment-related complications). Kaplan-Meier survival analysis showed significantly longer recurrence-free survival and overall survival in major responders (56.4+/-9.2 and 58.1+/-2.2 months) as compared with non-major responders (33.7+/-23.2 and 44.7+/-20.0 months), with p<0.0001 and p=0.0024, respectively.

CONCLUSION

The results of this study suggest that early restaging by a single whole-body (18)F-FDG PET scan after the first or second course of IC is useful for predicting therapeutic response and outcome in patients with locoregionally advanced NPC.

90Y microsphere treatment of unresectable liver metastases: changes in 18F-FDG uptake and tumour size on PET/CT

PURPOSE

The intra-arterial administration of 90Y microspheres is a new palliative treatment option for unresectable liver metastases. The aim of this study was to quantitatively assess changes in FDG uptake and tumour size following 90Y microsphere treatment (SIR-Spheres) using 18F-fluorodeoxyglucose (FDG) PET/CT imaging.

METHODS

Five patients with unresectable liver metastases who had failed multiple prior chemotherapy regimens received seven 90Y microsphere treatments to a single liver lobe. All patients underwent a baseline PET/CT scan prior to treatment, as well as up to four follow-up PET/CT scans. The tumour area of 30 liver metastases was measured on CT and the FDG uptake was semiquantitatively assessed by calculation of standardised uptake values (SUVs). A total of 18 FDG-PET/CT scans were performed.

RESULTS

The SUVs in the 30 treated liver metastases decreased from 6.5+/-2.3 at baseline to 4.2+/-1.8 after the first follow-up PET/CT scan (p=0.001). In contrast, the SUVs of untreated metastases increased slightly from 7.2+/-2.3 to 8.0+/-0.8. There was no difference in FDG uptake in treated versus untreated normal liver tissue. Using a previously defined threshold of 20% decrease in SUV from baseline to determine response, 20 out of 30 liver metastases were considered to have responded at the first follow-up PET/CT scan approximately 1 month after treatment. In these metastases, the SUV decreased by 47+/-12%, compared with a slight increase by 5.9+/-19% in ten non-responding metastases (p=0.0001). The changes in tumour size did not correlate with changes in FDG uptake. On the first follow-up PET/CT scan, the tumour area on CT increased by 3.1+/-57% in treated metastases compared with 23.3+/-32% in untreated metastases. A wide range of post-treatment changes of target lesions was observed on CT, including an increase in the size of hypodense lesions, necrotic features and complete resolution of CT abnormalities.

CONCLUSION

The metabolic information obtained from FDG-PET/CT seems to provide a more accurate and earlier assessment of therapy response following 90Y microsphere treatment than does the anatomical CT information.

Monitoring response to treatment in patients utilizing PET

Establishing new surrogate end points for monitoring response to treatment is needed for current therapy modalities and for new therapeutic strategies including molecular targeted cancer therapies. PET as a functional imaging technology provides rapid, reproducible, noninvasive in vivo assessment and quantification of several biologic processes targeted by these therapies. PET is useful in a variety of clinical relevant applications, including distinguishing between radiation necrosis and tumor recurrence, determining the resectability of recurrent tumor, and evaluating response to therapy. FDG-PET has demonstrated efficacy for monitoring therapeutic response in a wide range of cancers, including breast, esophageal, lung, head and neck, and lymphoma. FDG-PET can assess tumor glucose use with high reproducibility. Following therapy, the decrease of glucose use correlates with the reduction of viable tumor cells. FDG-PET allows the prediction of therapy response early in the course of therapy and determining the viability of residual masses after completion of treatment. The molecular basis for the success of FDG-PET is the rapid reduction of tumor glucose metabolism in effective therapies. Of even higher clinical relevance is the accurate identification of nonresponders in patients without a significant change in tumor glucose metabolism after initiation of therapy. PET imaging can easily visualize these changes in metabolic activity and indicate, sometimes within hours of the first treatment, whether or not a patient will respond to a particular therapy. In contrast to CT, MR imaging, or ultrasound, PET imaging allows identification of responding and nonresponding tumors early in the course of therapy. With this information, physicians can rapidly modify ineffective therapies for individual patients and thereby potentially improve patient outcomes and reduce cost. One of the major limitations for the routine application of FDG-PET imaging for therapy monitoring is that no generally accepted cutoff values have been established to differentiate optimally between responders and nonresponders. The patient series are still relatively small and frequently consist of different tumor types and different therapy regimens. Prospective studies including a sufficient number of patients are needed to define cutoff values to differentiate between responder and nonresponder for different tumors and different treatment regimes. In the future, PET imaging can also serve in the evaluation of new therapeutic agents, new experimental treatments, and specifically in monitoring clinical phase II studies.

Use of positron emission tomography in localized extremity soft tissue sarcoma treated with neoadjuvant chemotherapy

BACKGROUND

Patients with high-grade soft tissue sarcomas are at high risk of developing local disease recurrence and metastatic disease. [F-18]-fluorodeoxy-D-glucose (FDG) positron emission tomography (PET) scans are hypothesized to detect histopathologic response to therapy and to predict risk of tumor progression in patients with various malignancies. Serial FDG-PET scans were taken to determine the correlation between FDG uptake and patient outcomes in patients receiving multimodality treatment of extremity sarcomas.

METHODS

Forty-six patients with high-grade localized sarcomas were studied. The maximum standardized uptake values (SUVmax) of tumors were measured before receipt of neoadjuvant chemotherapy and again before surgery. Resected specimens were examined for residual viable tumor. Patients were followed up at least annually for evidence of local and distant recurrence of disease and survival.

RESULTS

Patients with a baseline tumor SUVmax >/= 6 and < 40% decrease in FDG uptake were at high risk of systemic disease recurrence estimated to be 90% at 4 years from the time of initial diagnosis. Patients whose tumors had a >/= 40% decline in the SUVmax in response to chemotherapy were at a significantly lower risk of recurrent disease and death after complete resection and adjuvant radiotherapy.

CONCLUSIONS

The FDG-PET scan was found to be a useful method with which to predict the outcomes of patients with high-grade extremity soft tissue sarcomas treated with chemotherapy. The pretreatment tumor SUVmax and change in SUVmax after neoadjuvant chemotherapy independently identified patients at high risk of tumor recurrence. The FDG-PET scan showed promise as a tool to identify the patients with sarcoma who are most likely to benefit from chemotherapy.

Methotrexate-Induced Accumulation of Fluorescent Annexin V in Collagen-Induced Arthritis

We examined the accumulation of Cy5.5-labeled annexin V in the paws of mice with and without collagen-induced arthritis, with and without methotrexate (MTX) treatment, by near-infrared fluorescence imaging. Fluorescence reflectance imaging (FRI) of paws was performed 48 hr after MTX injection and at 10 min and 3 hr after the injection of Cy5.5-annexin V (1 nmol dye per mouse). With arthritic paws, MTX treatment caused a 7-fold increase in fluorescence intensity compared with the paws of untreated mice and a 4-fold increase compared to nonarthritic paws of MTX-treated mice (p < .001 each). Tissue samples of paws were examined histologically for Cy5.5 fluorescence and by TUNEL staining for apoptosis. Cy5.5-annexin V was seen in the hyperplastic synovia of MTX-treated mice, and TUNEL staining for apoptosis showed apoptotic cells in the hyperplastic synovia. Monitoring the uptake of Cy5.5-annexin V in arthritic paws by FRI provided a method of assessing a response to MTX, a response that was readily quantitated with simple instrumentation and that occurred before conventional measurements of treatment response.

PET imaging in assessing gastrointestinal tumors

The clinical usefulness of FDG-PET imaging is now firmly established in various situations, such as the preoperative staging of esophageal cancer and recurrent colorectal carcinoma and the detection and staging of recurrent colorectal cancer when there is a clinical or biologic suspicion with inconclusive conventional findings. Encouraging results were obtained in the evaluation of the therapeutic response of various gastrointestinal malignancies, either during the treatment or after its completion. There is no firm consensus regarding its role in pancreatic cancer, either proved or suspected, but it may be valuable in selected clinical situations. Its role seems fairly limited in patients with hepatocellular carcinoma, although PET findings may have prognostic implications. Evaluation of cholangiocarcinoma is an emerging indication, albeit with limited data to date. Finally, PET/CT is very likely to enhance the role of FDG imaging further in the work-up of patients with gastrointestinal tumors.

Incidence of anemia in patients receiving neoadjuvant chemotherapy for locally advanced esophagogastric cancer

BACKGROUND

There is rising evidence that anemia and blood transfusion increase perioperative mortality in cancer patients. Patients who are treated with neoadjuvant chemotherapy with a curative intent are exposed to toxicity that may negatively affect their future outcome.

METHODS

The charts of 29 patients (21 males; median age, 59.5 years; range, 37 to 73), receiving neoadjuvant chemotherapy for cT3 esophagogastric adenocarcinoma operated at a single university center in the year 2002, were retrospectively reviewed to assess the incidence of anemia and blood transfusions.

RESULTS

Twenty-six patients received platinum-based chemotherapy over a period of 12 weeks and three patients more than 6 weeks. The median hemoglobin level (Hb level) before chemotherapy was 14.0 g/dL (range, 10.4 to 15.9 g/dL), the median decline of the Hb level was 2.9 g/dL (range, 0.3 to 6.3 g/dL); this drop was statistically significant (p < 0.001, 95% confidence interval). Patients who received preoperative blood transfusions (n = 8, 28%) had a significantly increased risk of developing postoperative complications (p = 0.028).

CONCLUSIONS

Preoperative chemotherapy for locally advanced esophagogastric cancer induces anemia and therefore leads to preoperative blood supplementation in a considerable number of patients. Data indicate that this may counteract the beneficial effects of neoadjuvant treatment.

Comparison of different SUV-based methods for monitoring cytotoxic therapy with FDG PET

PURPOSE

Fluorine-18 fluorodeoxyglucose positron emission tomography (FDG PET) is a promising tool for monitoring cytotoxic therapy in tumours. Due to the limited data available, a standard imaging protocol for the prediction of tumour response has not yet been approved. The aim of this study was to compare commonly applied imaging protocols and calculations of the standardised uptake value (SUV) for the early prediction of histopathological response to chemotherapy.

METHODS

Serial FDG PET scans of 43 patients with gastric carcinomas were retrospectively analysed. All patients received two consecutive scans (one bed position at 40 min p.i. and four bed positions at 90 min p.i.) at baseline and during the first cycle of cisplatinum-based chemotherapy. Reconstruction of the images was performed by filtered back-projection (FBP) and using an iterative algorithm (OSEM). SUVs were calculated with and without correction for the blood glucose level using normalisation by body weight, body surface area and lean body mass. Relative percentage changes between SUVs at baseline and follow-up were calculated and analysed for their potential to predict histopathological response to chemotherapy (ROC analysis). Response was defined as less than 10% viable tumour cells in the tumour specimen obtained by surgery 3-4 weeks after the completion of chemotherapy.

RESULTS

Eight of 43 patients were histopathological responders to chemotherapy. The percentage changes in SUV(body weight) for responders and non-responders were -52.2 (+/-13.2) and -25.2 (+/-15.2), -54.7 (+/-18.2) and -24.5 (+/-16.1), -53.9 (+/-24.2) and -22.7 (+/-21.3), and -56.7 (+/-21.6) and -26.1 (+/-18.9) for serial scans at 40-min FBP, 40-min OSEM, 90-min FBP and 90-min OSEM, respectively (responders versus non-responders: p<0.01 in each case). According to ROC analysis, neither the scan protocol nor correction for blood glucose significantly influenced the accuracy (approx. 80%) or the cut-off value (approx. -40% change in tumour SUV) for the prediction of response. Normalisation of SUVs by body surface area or lean body mass instead of body weight yielded essentially identical results.

CONCLUSION

In gastric carcinomas the prediction of response to chemotherapy on the basis of relative tumour SUV changes is not essentially influenced by any of the methodological variations investigated (time delay after FDG administration, acquisition protocol, reconstruction algorithm, normalisation of SUV). This demonstrates the robustness of FDG PET for therapeutic monitoring and facilitates the comparability of studies obtained at different institutions and with different protocols. However, whichever method is used for therapy monitoring with FDG PET, a highly standardised protocol must be observed to take the dynamics of tumour FDG uptake into account.

Positron emission tomography in gastric and esophageal cancer

PURPOSE OF REVIEW

Positron emission tomography using the positron emitting glucose analogue 18F-fluorodeoxyglucose has recently emerged as a promising metabolism-based whole-body imaging tool for cancer diagnosis and follow-up. Several reports have recently appeared indicating the potential and limitations of this technique. The review limits its scope to the recent advances of 18F-fluorodeoxyglucose positron emission tomography in the clinical management of gastric and esophageal cancer.

RECENT FINDINGS

New studies have been reported on the use of 18F-fluorodeoxyglucose positron emission tomography to assess the early and late metabolic response of a gastroesophageal tumor to chemo(radiation) therapy. The metabolic response as measured by serial 18F-fluorodeoxyglucose positron emission tomography, performed before and during treatment or some weeks thereafter, can be used to predict the clinical and histopathologic response. Moreover, the metabolic positron emission tomography response seems to be related to overall and disease-free survival.

SUMMARY

Gastroesophageal 18F-fluorodeoxyglucose positron emission tomography could add significant diagnostic information to the different phases of patient management. At initial diagnosis of esophageal cancer, positron emission tomography detects more distant lymph node and organ metastases compared with conventional diagnostics, allowing a more accurate selection of the most appropriate treatment. Serial 18F-fluorodeoxyglucose positron emission tomography performed before and during chemotherapy allows early identification of nonresponding tumors. 18F-fluorodeoxyglucose positron emission tomography performed after a treatment allows accurate assessment of the residual tumor load. 18F-fluorodeoxyglucose positron emission tomography allows accurate detection and restaging of recurrent disease.

Neoadjuvant therapy for oesophagogastric cancer

BACKGROUND

The prognosis after surgery for oesophagogastric cancer remains poor.

METHODS

This review clarifies current indications for neoadjuvant therapy for oesophageal and gastric cancer. A systematic literature research and evaluation of data from international cancer meetings were carried out.

RESULTS

Recently published results of large randomized phase III trials underscore the potential value of neoadjuvant treatment for oesophagogastric cancer. However, it remains uncertain which subgroups of patients should routinely undergo preoperative therapy. Metabolic response evaluation during neoadjuvant treatment is a promising tool for the selection of responding patients.

CONCLUSION

Neoadjuvant chemotherapy is a valid option for locally advanced oesophageal and gastric cancer. In the future, more effective and better tolerated treatment strategies, tailored to the specific tumour characteristics of each individual, should be possible.

(Neo)adjuvant strategies of advanced gastric carcinoma: time for a change?

Despite surgical R0 resections, patients with gastric cancer stage UICC II-III have a high risk of recurrence and metachronic metastases. Preliminary evidence exists that adjuvant chemotherapy or neoadjuvant chemo(radio)therapy protocols may improve the prognosis of these patients undergoing surgery of gastric cancer with curative intention. As for palliative regimens, 5-fluorouracil and cisplatin are integral components of such (neo)adjuvant strategies. Upcoming cytostatic agents, i.e. irinotecan, docetaxel, oxaliplatin, and oral fluoropyridines are currently under investigation in new multimodality treatment regimens and may further increase R0 resection rates and may prolong disease-free and overall survival in the treatment of advanced localized gastric cancer.