Is standardised 18F-FDG uptake value an outcome predictor in patients with stage III non-small cell lung cancer?

Prognostic value of serial [18F]fluorodeoxyglucose PET-CT uptake in stage III patients with non-small cell lung cancer treated by concurrent chemoradiotherapy

OBJECTIVE

To evaluate (18)FDG PET-CT for the assessment of therapy response and prediction of patient outcome after concurrent chemoradiotherapy (CCRT) for non-small cell lung cancer (NSCLC).

METHODS

Forty-six patients with pathologically proven stage III NSCLC had 2 serial FDG PET-CT scans, before and during CCRT. The maximum standardized uptake value (SUV(max)) of the primary lung lesion was calculated. The value changes of SUV(max) before and during treatment were calculated according to the following equation: SUV=(SUV(before)-SUV(during))100%/SUV(before). The relationship between changes of the SUV(max) and the therapy response as well as long-term survival was studied in the responsive and non-responsive groups after CCRT.

RESULTS

Of the 46 enrolled patients, after a medicine follow-up of 2 years, the initial SUV(max) in the responsive and non-responsive groups was 7.59±3.14 and 14.72±4.67, respectively. The SUV(max) during treatment in the two groups was 2.89±1.39 and 9.82±3.31, respectively. Significant difference (P=0.001; P=0.001) in SUV(max) was observed either before or during treatment. Furthermore, the percent change of SUV(max) before and during treatment was 61.91±86.69 and 33.56±90.37, respectively. There was significant difference between these two groups (P=0.007). In addition, the 1-year survival rate in the responsive and non-responsive group was 73% and 69%, respectively. The 2-year survival rate in the two groups was 40% and 37%, respectively. There was significant difference between these two groups (P=0.001).

CONCLUSIONS

(18)FDG PET-CT is an effective method in the prediction of therapy response in patients with stage III NSCLC. The analysis of percent change of SUV(max) provides additional value in early prediction of therapy response and patient outcome.

Identification of residual metabolic-active areas within individual NSCLC tumours using a pre-radiotherapy (18)Fluorodeoxyglucose-PET-CT scan

BACKGROUND AND PURPOSE

Non-small cell lung cancer (NSCLC) tumours are mostly heterogeneous. We hypothesized that areas within the tumour with a high pre-radiation (18)F-deoxyglucose (FDG) uptake, could identify residual metabolic-active areas, ultimately enabling selective-boosting of tumour sub-volumes.

MATERIAL AND METHODS

Fifty-five patients with inoperable stage I-III NSCLC treated with chemo-radiation or with radiotherapy alone were included. For each patient one pre-radiotherapy and one post-radiotherapy FDG-PET-CT scans were available. Twenty-two patients showing persistent FDG uptake in the primary tumour after radiotherapy were analyzed. Overlap fractions (OFs) were calculated between standardized uptake value (SUV) threshold-based auto-delineations on the pre- and post-radiotherapy scan.

RESULTS

Patients with residual metabolic-active areas within the tumour had a significantly worse survival compared to individuals with a complete metabolic response (p=0.002). The residual metabolic-active areas within the tumour largely corresponded (OF>70%) with the 50%SUV high FDG uptake area of the pre-radiotherapy scan. The hotspot within the residual area (90%SUV) was completely within the GTV (OF=100%), and had a high overlap with the pre-radiotherapy 50%SUV threshold (OF>84%).

CONCLUSIONS

The location of residual metabolic-active areas within the primary tumour after therapy corresponded with the original high FDG uptake areas pre-radiotherapy. Therefore, a single pre-treatment FDG-PET-CT scan allows for the identification of residual metabolic-active areas.

Biologically conformal treatment: biomarkers and functional imaging in radiation oncology

'Conformal radiation therapy' is the standard of care in radiation oncology, referring to the process of shaping the radiation beam to precisely match a tumor's physical dimensions. We describe 'biologically conformal radiotherapy', in which the radiation oncologist matches the prescribed treatment to a tumor's biological characteristics and the host's predicted tolerance of radiation. This paradigm emphasizes that not all tumors are equally sensitive to radiation; conversely, some patients are especially susceptible to radiation's side effects. Patients bearing radioresistant tumors or those prone to toxicity may be best treated with the incorporation of targeted radiation modulators or, in extreme cases, by a different modality. The biological characteristics of tumors can be assessed by a wide range of techniques: functional imaging (positron emission tomography and advanced magnetic resonance imaging), single gene/protein molecular techniques and 'omic' technologies. This paper reviews the latest advances in the use of biomarkers and functional imaging in guiding patients to receive the most appropriate treatment.

Intratumoral metabolic heterogeneity of cervical cancer

PURPOSE

Previous research has shown that the intertumoral maximum standardized uptake value (SUVMax) of F-18 fluorodeoxyglucose (FDG)-positron emission tomography (PET) for cervical cancer predicts disease outcome. The purpose of this study was to evaluate the pretreatment intratumoral metabolic heterogeneity of FDG.

EXPERIMENTAL DESIGN

This is a prospective cohort study of 72 patients with International Federation of Gynecology and Obstetrics stages Ib1 to IVa cervical cancer treated with chemoradiation. Three-dimensional FDG-PET threshold tumor volumes were calculated using image segmentation and an adaptive thresholding method for the primary cervix tumor from the pretreatment FDG-PET/computerized tomography. Intratumor heterogeneity was obtained for each patient's cervical tumor by taking the derivative (dV/dT) of the volume-threshold function from 40% to 80%. The association between intratumoral heterogeneity and tumor-specific factors and patient outcomes were determined.

RESULTS

The mean cervix tumor SUV(Max) was 12.4 (range, 3.0-38.4). The mean differential tumor heterogeneity was -1.074 (range, -0.107 to -5.623). There was no association between dV/dT and SUVMax (R2 = 0.069), but there was a relationship with dV/dT and tumor volume (R2 = 0.881). There was no correlation of dV/dT with tumor histology (P = 0.4905). Heterogeneity was significantly associated with the risk of lymph node metastasis at diagnosis (P = 0.0009), tumor response to radiation as evaluated by FDG-PET obtained 3 months after completing treatment (P = 0.0207), risk of pelvic recurrence (P = 0.0017), and progression-free survival (P = 0.03).

CONCLUSIONS

Cervical intratumoral FDG metabolic heterogeneity on the pretreatment FDG-PET predicts risk of lymph node involvement at diagnosis, response to therapy, and risk of pelvic recurrence.

Molecular imaging of metastatic potential

If molecular imaging is to prove clinically useful it will have to surpass current, primarily anatomic techniques in terms of sensitivity and the ability to detect minimal changes in tissue. One of the most important tests for molecular imaging is to determine whether it can image the metastatic potential of tumors. Like all predictive endeavors, the imaging of such "potential" is a daunting task, but one that only molecular imaging--rather than standard, anatomic techniques--is likely to solve. Although difficult, imaging of metastatic potential is also arguably the most important task for molecular imaging of cancer because it is generally the dissemination of malignant tissue, not its prolonged residence in an inopportune site, which kills the patient. Below are examples of uses of molecular imaging of metastases as well as of metastatic potential, the former being a far more developed area of clinical inquiry.

The prognostic value of PET and PET/CT in cervical cancer

Cervical cancer ranks among the top three cancer diagnoses in women worldwide. In the United States, the SEER Cancer Statistics Review identified cervical cancer as the third leading cause (following childhood cancers and testicular cancer) of average years of life lost per person dying of cancer for all races and both genders. Approximately one-third of cervical cancer patients develop disease recurrence and the majority of these recurrences occur within the first 2 years after completion of therapy. Predictors of disease recurrence include stage and lymph node status at the time of initial diagnosis. The initial diagnosis and staging of cervical cancer has traditionally been achieved by history and physical examination and by use of selected imaging studies. Accurate staging is important both for selecting appropriate therapy and for prognosis. Computed tomography (CT) has been the most widely used imaging method for assessment of nodal involvement and detection of distant metastatic disease. Positron emission tomography (PET) has become an established imaging tool for cervical cancer. The functional information about regional glucose metabolism provided by fluorodeoxyglucose (FDG)-PET provides for greater sensitivity and specificity in most cancer imaging applications by comparison with CT and other anatomic imaging methods. PET is superior to conventional imaging modalities for evaluating patients with cervical cancer.

Predictive and prognostic value of FDG-PET

The predictive and prognostic value of fluorodeoxyglucose (FDG)-positron emission tomography (PET) in non-small-cell lung carcinoma, colorectal carcinoma and lymphoma is discussed. The degree of FDG uptake is of prognostic value at initial presentation, after induction treatment prior to resection and in the case of relapse of non-small cell lung cancer (NSCLC). In locally advanced and advanced stages of NSCLC, FDG-PET has been shown to be predictive for clinical outcome at an early stage of treatment. In colorectal carcinoma, limited studies are available on the prognostic value of FDG-PET, however, the technique appears to have great potential in monitoring the success of local ablative therapies soon after intervention and in the prediction and evaluation of response to radiotherapy, systemic therapy, and combinations thereof. The prognostic value of end-of treatment FDG-PET for FDG-avid lymphomas has been established, and the next step is to define how to use this information to optimize patient outcome. In Hodgkin's lymphoma, FDG-PET has a high negative predictive value, however, histological confirmation of positive findings should be sought where possible. For non-Hodgkin's lymphoma, the opposite applies. The newly published standardized guidelines for interpretation formulates specific criteria for visual interpretation and for defining PET positivity in the liver, spleen, lung, bone marrow and small residual lesions. The introduction of these guidelines should reduce variability among studies. Interim PET offers a reliable method for early prediction of long-term remission, however it should only be performed in prospective randomized controlled trials. Many of the diagnostic and management questions considered in this review are relevant to other tumour types. Further research in this field is of great importance, since it may lead to a change in the therapeutic concept of cancer. The preliminary findings call for systematic inclusion of FDG-PET in therapeutic trials to adequately position FDG-PET in treatment time lines.

Primary tumor standardized uptake value (SUVmax) measured on fluorodeoxyglucose positron emission tomography (FDG-PET) is of prognostic value for survival in non-small cell lung cancer (NSCLC): a systematic review and meta-analysis (MA) by the European Lung Cancer Working Party for the IASLC Lung Cancer Staging Project

HYPOTHESIS

The 2-[18F]-fluoro-2-deoxy-d-glucose positron emission tomography is an imaging tool for assessing clinical tumor, node, metastasis in non-small cell lung cancer (NSCLC). Primary tumor standardized uptake value (SUV) has been studied as a potential prognostic factor for survival. However, the sample sizes are limited leading to conduct a meta-analysis to improve the precision in estimating its effect.

METHODS

We performed a systematic literature search. For each publication, we extracted an estimate of the hazard ratio (HR) for comparing patients with a low and a high SUV and we aggregated the individual HRs into a combined HR, using a random-effects model.

RESULTS

We found 13 eligible studies dedicated to NSCLC. Most of them included patients with stages I to III/IV and used a SUV assessment corrected for body weight. Number of patients ranged from 38 to 315 (total: 1474); 11 studies identified a high SUV as a poor prognostic factor for survival although two studies found no significant correlation between SUV and survival. SUV measurement and SUV threshold for defining high SUV were study dependent, eight studies looked for a so-called best cutoff (maximizing the logrank test statistic) without adjusting the p value for multiplicity. Overall, the combined HR for the 13 reports was 2.27 (95% confidence interval [CI]: 1.70-3.02); excluding the studies proposing a "best" cutoff, it was 2.08 (95% CI: 1.431-3.04).

CONCLUSION

Our meta-analysis suggests that the primary tumor SUV measurement has a prognostic value in NSCLC; these results should be confirmed in a meta-analysis on individual patients' data.

The standardized uptake value for F-18 fluorodeoxyglucose is a sensitive predictive biomarker for cervical cancer treatment response and survival

BACKGROUND

The objective of this study was to evaluate cervical tumor uptake of F-18 fluorodeoxyglucose (FDG) measured as the maximal standardized uptake value (SUV(max)) by positron emission tomography (PET) and its association with treatment response and prognosis in patients with cervical cancer.

METHODS

The study population consisted of 287 patients with stage IA2 through IVB cervical cancer who underwent pretreatment FDG-PET studies. SUV(max), tumor volume, and sites of lymph node metastasis were recorded. Therapy included surgery, chemoradiation, or palliation.

RESULTS

The mean SUV(max) was 11.4 (range, 1-50.4). The mean tumor volume by stage was 42.1 cm(3) for stage I tumors (using International Federation of Gynecology and Obstetrics [FIGO] staging criteria), 63.7 cm(3) for stage II tumors, 129.2 cm(3) for stage III tumors, and 166.2 cm(3) for stage IV tumors. There was no correlation between tumor volume and SUV(max) (correlation coefficient [R(2)] = 0.01). No significant difference in SUV(max) was observed between squamous histology (n = 247 patients) and nonsquamous histology (n = 40 patients; P = .089). Higher SUV(max) was associated with an increased risk of lymph node metastasis at diagnosis (P = .0009). A Cox proportional-hazards model for death from cervical cancer was used to evaluate tumor histology, lymph node metastasis, tumor volume, and SUV(max). The results indicated that SUV(max) was the only significant independent factor (P = .0027). Three prognostic groups were established using SUV(max). The overall survival rates at 5 years were 95% for an SUV(max) </= 5.2, 70% for an SUV(max) > 5.2 and </=13.3, and 44% for an SUV(max) > 13.3 (P < .0001). Increasing SUV(max) was associated with persistent abnormal FDG uptake in the cervix on 3-month FDG-PET studies in 238 patients who received curative chemoradiation (P = .04).

CONCLUSIONS

The SUV(max) of the cervical tumor at diagnosis was a sensitive biomarker of treatment response and prognosis for patients with cervical cancer.

Predictive and prognostic value of FDG-PET in nonsmall-cell lung cancer: a systematic review

For several years, molecular imaging with (18)F-fluorodeoxyglucose positron emission tomography (FDG-PET) has become part of the standard of care in presurgical staging of patients with nonsmall-cell lung cancer (NSCLC), focusing on the detection of malignant lesions at early stages, early detection of recurrence, and metastatic spread. Currently, there is an increasing interest in the role of FDG-PET beyond staging, such as the evaluation of biological characteristics of the tumor and prediction of prognosis in the context of treatment stratification and the early assessment of tumor response to therapy. In this systematic review, the literature on the value of the evolving applications of FDG-PET as a marker for prediction (ie, therapy response monitoring) and prognosis in NSCLC is addressed, divided in sections on the predictive value of FDG-PET in locally advanced and advanced disease, the prognostic value of FDG-PET at diagnosis, after induction treatment, and in recurrent disease. Furthermore, the background and recommendations for the application of FDG-PET for these indications will be discussed.

Metabolic Tumor Burden Predicts for Disease Progression and Death in Lung Cancer

PURPOSE

In lung cancer, stage is an important prognostic factor for disease progression and survival. However, stage may be simply a surrogate for underlying tumor burden. Our purpose was to assess the prognostic value of tumor burden measured by 18F-fluorodeoxyglucose-positron emission tomography (FDG-PET) imaging.

PATIENTS AND METHODS

We identified 19 patients with lung cancer who had staging PET-CT scans before any therapy, and adequate follow-up (complete to time of progression for 18, and death for 15 of 19). Metabolically active tumor regions were segmented on pretreatment PET scans semi-automatically using custom software. We determined the relationship between times to progression (TTP) and death (OS) and two PET parameters: total metabolic tumor volume (MTV), and standardized uptake value (SUV).

RESULTS

The estimated median TTP and OS for the cohort were 9.3 months and 14.8 months. On multivariate Cox proportional hazards regression analysis, an increase in MTV of 25 ml (difference between the 75th and 25th percentiles) was associated with increased hazard of progression and of death (5.4-fold and 7.6-fold), statistically significant (p = 0.0014 and p = 0.001) after controlling for stage, treatment intent (definitive or palliative), age, Karnofsky performance status, and weight loss. We did not find a significant relationship between SUV and TTP or OS.

CONCLUSIONS

In this study, high tumor burden assessed by PET MTV is an independent poor prognostic feature in lung cancer, promising for stratifying patients in randomized trials and ultimately for selecting risk-adapted therapies. These results will need to be validated in larger cohorts with longer follow-up, and evaluated prospectively.

Repeat 18F-FDG PET for monitoring neoadjuvant chemotherapy in patients with stage III non-small cell lung cancer

PURPOSE

The relevance of (18)F-FDG PET for staging non-small cell lung cancer (NSCLC), in particular for the detection of lymph node or distant metastases, has been shown in several studies. The value of FDG-PET for therapy monitoring in NSCLC, in contrast, has not yet been sufficiently analysed. Aim of this study was to evaluate FDG-PET for monitoring treatment response during and after neoadjuvant radiochemotherapy (NARCT) in advanced NSCLC.

METHODS

Sixty-five patients with histologically proven NSCLC stage III initially underwent three FDG-PET investigations, during NARCT prior to initiating radiation, and post-NARCT. Changes of FDG-uptake in the primary tumour at two time-points during NARCT were analysed concerning their impact on long-term survival.

RESULTS

The mean maximum FDG uptake (standardized uptake value, SUVmax) of the whole group decreased significantly during NARCT (SUVmax PET 1: 14.9+/-4.0, SUVmax PET 3: 5.5+/-2.4, p=0.004). The difference between initial FDG uptake (PET 1) and uptake after induction chemotherapy (PET 2) was found to be highly predictive for long-term survival patients which had a greater than 60% decreases in their SUV change had a significantly longer survival than those below this threshold (5-year-survival 60% versus 15%, p=0.0007). Patients who had a lower than 25% decrease in their SUV change had a 5-years-survival lower than 5%. Furthermore, the difference between initial FDG uptake (PET 1) and uptake after completion of the whole NARCT (PET 3) was predictive for survival when 75% was applied as cut-off (p=0.02). However, the level of significance was considerably lower.

CONCLUSION

FDG-PET is suitable for therapy monitoring in patients with stage III NSCLC. The decrease of FDG uptake during induction chemotherapy is highly predictive for patient outcome.

Time trends in the maximal uptake of FDG on PET scan during thoracic radiotherapy. A prospective study in locally advanced non-small cell lung cancer (NSCLC) patients

BACKGROUND AND PURPOSE

18F-fluoro-2-deoxy-glucose (FDG) uptake on PET scan is a prognostic factor for outcome in NSCLC. We investigated changes in FDG uptake during fractionated radiotherapy in relation to metabolic response with the ultimate aim to adapt treatment according to early response.

METHODS AND MATERIALS

Twenty-three patients, medically inoperable or with advanced NSCLC, underwent four repeated PET-CT scans before, during and after radiotherapy. Changes in maximal standardized uptake value (SUVmax) were described. Patients were treated with accelerated radiotherapy with a total tumour-dose depending on normal tissue dose constraints.

RESULTS

The most striking result was the large intra-individual heterogeneity in the evolution of SUVmax. For the total group a non-significant increase in the first week (p=0.05), and a decrease in the second week (p=0.02) and after radiotherapy (p<0.01) was observed. Different time trends were shown for responders (no change during radiotherapy) and non-responders (48% increase during first week, p=0.02 and 15% decrease in the second week, p=0.04). Non-responders had a higher SUVmax on all time points investigated.

CONCLUSIONS

Time trends in SUVmax showed a large intra-individual heterogeneity and different patterns for metabolic responders and non-responders. These new findings may reflect intrinsic tumour characteristics and might finally be useful to adapt treatment.

PET/CT in non-small cell lung cancer staging—promises and problems

Integrated positron emission tomography/computed tomography (PET/CT) has many advantages over solitary PET and CT, which has led it to become an increasingly established imaging technique in the management of many cancers. This article will review the evidence for the role of (18)F-fluorodeoxyglucose PET/CT in non-small cell lung cancer staging, examining its strengths, weaknesses and cost-effectiveness.

Biological correlates of FDG uptake in non-small cell lung cancer

PURPOSE

Each pathological stage of non-small cell lung cancer (NSCLC) consists of a heterogeneous population containing patients at much higher risk than others. Noninvasive functional imaging modalities, such as 18F-fluorodeoxyglucose positron emission tomography (FDG-PET), could play a role in further characterization of NSCLCs. As many factors can influence the extent of FDG uptake, the underlying mechanisms for FDG accumulation in tumors, are still a matter of debate. The aim of the present study was to investigate these possible mechanisms in the primary site of early stage preoperatively untreated NSCLC.

METHODS

19 patients with early stage NSCLC, who had undergone both preoperative FDG-PET imaging and curative surgery, were enrolled in this study. Standardized uptake values (SUVs) were used for evaluation of primary tumor FDG uptake. Final diagnosis, tumor type, tumor cell differentiation and size of the primary tumors were confirmed histopathologically in resected specimens. Histologic sections were analyzed for amount of inflammation and necrosis. Expression of the glucose membrane transporters (GLUT-1 and GLUT-3); the isoforms of the glycolytic enzyme hexokinase (HK-I, HK-II and HK-III); and the cysteine protease caspase-3, was evaluated immunohistochemically.

RESULTS

FDG uptake was significantly higher in squamous cell carcinomas (mean SUV 13.4+/-4.9, n=8) compared to adenocarcinomas (7.1+/-3.3, n=8, p=0.007), or large cell carcinomas (5.9+/-1.9, n=3, p=0.02). The degree of FDG accumulation seemed to depend especially on GLUT-1, GLUT-3 and tumor cell differentiation. The summed standardized values of these three parameters correlated significantly with the SUV (r=0.47, p=0.05).

CONCLUSION

The present study supports the hypothesis that tumor cell differentiation in combination with overexpression of GLUT-1 and GLUT-3 determine the extent of FDG accumulation and that squamous cell carcinomas accumulate more FDG than adenocarcinomas or large cell carcinomas.

18F-FDG PET for assessment of therapy response and preoperative re-evaluation after neoadjuvant radio-chemotherapy in stage III non-small cell lung cancer

PURPOSE

The aim of this study was to evaluate FDG-PET for assessment of therapy response and for prediction of patient outcome after neo-adjuvant radio-chemotherapy (NARCT) of advanced non-small cell lung cancer (NSCLC).

METHODS

Seventy patients with histologically proven stage III NSCLC underwent FDG-PET investigations before and after NARCT. Changes in FDG uptake and PET findings after completion of NARCT were compared with (1) the histology of tumour samples obtained at surgery or repeat mediastinoscopy, and (2) treatment results in terms of achieved operability and long-term survival.

RESULTS

The mean average FDG uptake of the primary tumours in the patient group decreased significantly during NARCT (p = 0.004). Sensitivity, specificity and overall accuracy of FDG-PET were 94.5%, 80% and 91%, respectively, for the detection of residual viable primary tumour, and 77%, 68% and 73%, respectively, for the presence of lymph node metastases. A negative PET scan or a reduction in the standardised uptake value (SUV) of more than 80% was the best predictive factor for a favourable outcome of further treatment. Progressive disease according to PET (new tumour manifestations or increasing SUV) was significantly correlated with an unfavourable outcome (p = 0.005). In this subgroup, survival of patients who underwent surgery was not significantly different from survival among those who did not undergo surgery, whereas for the whole patient group, complete tumour resection had a significant influence on outcome.

CONCLUSION

FDG-PET is suitable to assess response to NARCT in patients with stage III NSCLC accurately. It was highly predictive for treatment outcome and patient survival. PET may be helpful in improving restaging after NARCT by allowing reliable assessment of residual tumour viability.

Impact of staging with 18F-FDG-PET on outcome of patients with stage III non-small cell lung cancer: PET identifies potential survivors

Purpose:

The aim of this study was to analyse the impact of FDG-PET staging on treatment results of neo-adjuvant radiochemotherapy in patients with advanced non-small cell lung cancer (NSCLC). We compared prospectively the outcome of two patient groups with stage III NSCLC undergoing the same neo-adjuvant radio-chemotherapy (NARCT). In one group, FDG-PET was part of the pretherapeutic staging, whereas in the other group, no PET scans were performed.

Methods:

One hundred and eighty-eight patients with advanced stage III NSCLC were selected for a phase II trial of NARCT. The first 115 patients underwent conventional workup (CWU) and FDG-PET before inclusion (group I); the remaining 73 patients underwent CWU only (group II). All patients were followed up according to a standardised protocol for at least 11 months (up to 64 months). Overall survival and disease-free survival were used as parameters of therapeutic success and analysed statistically.

Results:

After staging, 157/188 patients were included in the clinical trial. Thirty-one were excluded owing to the results of FDG-PET, in most cases because of the detection of previously unknown distant metastases. Overall survival and metastasis-free survival were significantly longer in patients of group I stratified by FDG-PET than in group II (p=0.006 and 0.02 respectively). Another significant factor for survival was complete tumour resection (p=0.02). Gender, histological tumour type, tumour grade and UICC stage had no significant influence.

Conclusion:

Pretherapeutic staging by FDG-PET significantly influences the results of NARCT and subsequent surgery by identifying patients not eligible for curative treatment.