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J Thorac Cardiovasc Surg 2005;129:1232-1241
© 2005 The American Association for Thoracic Surgery
General Thoracic Surgery |
a Section of Thoracic Surgery, University of Alabama at Birmingham, Birmingham, Ala
d Division of Nuclear Radiology, University of Alabama at Birmingham, Birmingham, Ala
f Department of Medicine, Division of Gastroenterology and Hepatology, University of Alabama at Birmingham, Birmingham, Ala
b Division of Cardio-Thoracic Surgery, Department of Surgery, the Birmingham Veterans Administration Hospital, Birmingham, Ala
c Department of Epidemiology, University of Alabama at Birmingham School of Public Health, Birmingham, Ala
e Department of Biostatistics, University of Alabama at Birmingham School of Public Health, Birmingham, Ala
Read at the Thirtieth Annual Meeting of The Western Thoracic Surgical Association, Maui, Hawaii, June 2326, 2004.
Received for publication June 26, 2004; revisions received November 8, 2004; accepted for publication December 22, 2004. * Address for reprints: Robert J. Cerfolio, MD, Division of Cardiothoracic Surgery, University of Alabama at Birmingham, 1900 University Blvd, THT 712, Birmingham, AL 35294 (Email: robert.cerfolio{at}ccc.uab.edu).
| Abstract |
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METHODS: This is a prospective trial on a consecutive series of patients who had initial chest, abdomen, and pelvis CT scan; EUS-FNA; and fluoro-2-deoxy-D-glucose (FDG)-integrated PET/CT; neoadjuvant chemoradiotherapy; repeat staging tests; pathologic staging; and, if appropriate, resection with lymphadenectomy. The primary objective was to assess the accuracy of these 3 tests in restaging patients after neoadjuvant therapy.
RESULTS: There were 48 patients (41 men), and 41 underwent Ivor Lewis esophagogastrectomy with lymphadenectomy. The accuracy of each test for distinguishing pathologic T4 from T1 to T3 disease is 76%, 80%, and 80% for CT scan, EUS-FNA and FDG-PET/CT, respectively. The accuracy for nodal disease was 78%, 78%, and 93% for CT scan, EUS-FNA and FDG-PET/CT, respectively (P = .04). FDG-PET/CT correctly identified M1b disease in 4 patients, falsely suggested it in 4 patients, and missed it in 2 patients, whereas for CT, it was 3, 3, and 3 patients. Fifteen (31%) patients were complete responders, and FDG-PET/CT accurately predicted complete response in 89% compared with 67% for EUS-FNA (P = .045) and 71% for CT (P = .05).
CONCLUSIONS: FDG-PET/CT is more accurate than EUS-FNA and CT scan for predicting nodal status and complete responders after neoadjuvant therapy in patients with esophageal cancer. FDG-PET/CT and CT alone provide targets for biopsy, but results are often falsely positive.
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| Patients and Methods |
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For inclusion in this study, requirements included the following: biopsy-proved esophageal cancer; initial chest, abdomen and pelvis CT, EUS-FNA, and FDG-PET/CT; neoadjuvant chemoradiotherapy; repeat CT, EUS-FNA, and FDG-PET/CT; and pathologic staging. Patients with tissue confirmation of recalcitrant or progressive nodal or metastatic disease who did not undergo complete resection were also included in this study. Only magnetic resonance imaging of the brain or bone was accepted as proof of metastatic M1b disease; otherwise, tissue biopsy was required. Patients who underwent resection had to have had lymphadenectomy performed, as shown in Figure 1.
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After initial staging, all patients in this study underwent cisplatin-based chemotherapy with concomitant radiotherapy. After the completion of their neoadjuvant treatment, patients were restaged with the same 3 staging tests described below. A stage was assigned by using the TNM staging classification system2 after each test. Because CT, EUS-FNA, and FDG-PET could not differentiate T1, T2, or T3 disease, the accuracy for each test was assessed for its ability to predict T1 to T3 disease from T0 and T4 disease. Because EUS-FNA could not assess M1b disease (except for certain locations, such as the left adrenal gland, the lower lobes of the lung, or parts of the liver), M disease could be recorded as Mx disease.
| CT Scans |
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EUS-FNA
EUS was performed during conscious sedation, as previously described,10 and all tests were performed by a single experienced endosonographer (M.A.E.; >2500 EUS procedures). A radial echoendoscope (GF-UM130; Olympus America, Melville, NY) was first used to evaluate the presence or absence of lymphadenopathy. The examination started with full evaluation of the left lobe of the liver, the left adrenal gland (by imaging it from the fundus of the stomach and then gradually withdrawing it to evaluate the primary tumor), and all regional echo-visible lymph nodes. The perigastric, subhepatic, and celiac axis areas (M1a) were carefully evaluated for the presence of adenopathy. Once a suspicious lymph node (the endosonographic criteria for malignant lymph nodes involvement have been previously described11) was identified, the radial echoendoscope was removed, and a curvilinear echoendoscope (Olympus UC-30P or UCT 140) was inserted. EUS-FNA of the target lesion or lesions was performed as previously described.12 Peritumoral lymph nodes were not aspirated because of the risk of contamination from the primary tumor.
All EUS-FNAs were performed with 22-gauge adjustable-length Echotip needles (Wilson-Cook, Inc, Winston Salem, NC). Cytological diagnosis of the aspirated lesion (either of suspicious lymph nodes, M1a disease, or M1b disease) was reported as either positive for metastatic cancer or negative. If regional lymph nodes could not be aspirated because the primary tumor was intervening, the ultrasonographic characteristics were used to call the node positive or negative. The endosonographer (M.A.E.) was blinded to the CT report and to the FDG-PET report.
FDG-PET/CT
FDG-PET/CT was performed on a dedicated PET scanner with an integrated PET/CT system (GE Discovery LS PET/CT Scanner; GE, Milwaukee, Wis). Patients were asked to fast for 4 hours and then subsequently received 555 MBq (15 mCi) of FDG intravenously, followed by PET after 1 hour. The most recent CT scan of the chest was available for visual correlation of the integrated PET/CT result, but the reader (B.O.) was unaware of the EUS-FNA-predicted TNM stage or of the TNM-predicted stage of the CT scan.
Maximum standardized uptake value (maxSUV) was determined by drawing regions of interest on the attenuation-corrected FDG-PET images around the primary tumor. The maxSUV was calculated by using the software contained within the PET/CT scanner and the following formula13:
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A regional lymph node (N disease or M1a disease if a celiac node), as well as M1b disease, was considered positive on FDG-PET/CT scanning if the maxSUV was 2.5 or greater and the FDG-PET/CT report called the node malignant or highly suspicious for malignancy. In this study M1a disease was defined as celiac axis lymph node disease in patients with distal esophageal tumors.
Statistical Analysis
Data were stored by using an Access database (Microsoft) and analyzed with EpiInfo (CDC, Atlanta, Ga). Mortality was defined as any death occurring during the hospital stay or within 30 days postoperatively. Sensitivity, specificity, positive predicted value, negative predicted value, and accuracy were determined for CT, EUS-FNA, and FDG-PET/CT by using the pathology or biopsy results as the gold standard. Standard definitions were used to calculate these parameters.14 Differences between efficacy percentages were compared by using the test for proportions.
| Results |
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| T Status |
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| N Status |
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| M1a and M1b Disease |
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| Complete Responders |
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There were 23 patients who had biopsy-proved N1 disease before neoadjuvant therapy, and 8 of them had a complete pathologic response. There were 25 patients whose disease was staged as N0, and 7 were complete responders.
| Effect of Response to Chemoradiotherapy on Change in MaxSUV |
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| Discussion |
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| T Status |
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Zuccaro and colleagues17 in 1999, Laterza and associates18 in 1999, and Beseth and coworkers19 in 2000 have all shown that EUS-FNA cannot tell T1 from T2 or T3 disease after chemoradiotherapy. However, Willis and colleagues20 in 2002 and Chalk and associates21 in 2000 showed that a 50% or greater decrease of cross-sectional area, as determined by means of EUS, is a good predictor of response. We believe the distinction of T1 to T3 disease has little clinical importance anyway because resection is invariably recommended for posttherapy T1 to T3 lesions if patients have N0 disease. The important clinical question is determining who has T4 disease and perhaps should not undergo an operation because an R0 resection is not possible. Thus we evaluated the accuracy and negative predictive value of the restaging tests to answer this specific question. Because complete responders are a separate category that might benefit the most from resection,22,23 they were evaluated separately.
We were surprised to find that the negative predictive value is best for FDG-PET/CT at 95%. This might be because our study features an integrated PET/CT system as opposed to dedicated PET alone. This might be an important distinction of our study. We also found that none of the 3 tests were very good for ruling out T4 disease. In fact, making the clinical effect of our findings even more difficult to interpret is the fact that we were able to completely resect all 3 patients who turned out to have unsuspected T4 disease with negative margins. EUS-FNA defined 1 patients disease as T3 and the other 2 patients diseases as T2. One might argue that these patients had resectable T4 lesions, and thus EUS was correct in the sense that they were resectable, but the clinical effect of resected T4 versus nonresected T4 disease after neoadjuvant therapy is unknown. Thus we recommend that if a patients risk for surgical intervention is low, it makes sense to explore him or her to attempt R0 resection, even if the staging tests suggest T4 disease. More studies are needed to further examine these important questions not answered in this trial.
| Nodal Disease |
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FDG-PET results have been shown to be difficult to interpret after radiotherapy, and the best time to repeat an FDG-PET scan on a patient still remains unproved. In this report the median time between the completion of radiotherapy and the repeat FDG-PET/CT scan is 27 days. Our numbers are too low to perform a dose-response or a time-dependent analysis, but our preference is to wait at least 3 weeks before performing the second FDG-PET/CT scan. Importantly, it must be stressed that a negative FDG-PET/CT result of a regional lymph node after neoadjuvant therapy is not proof of benignancy, nor is a positive FDG-PET/CT result proof of cancer. It merely provides targets for biopsy to rule out cancer.
The ability of FDG-PET (not necessarily FDG-PET/CT) to discover unsuspected M1b disease is currently being studied in a multi-institutional prospective trial under the guise of the American College of Surgeons Oncology Group Trial Z0060. Pierre and colleagues26 in 2004 found that FDG-PET upstaged 20% of 74 patients and correctly downstaged 5%. However, he also found 7% false-positive results and 4% false-negative results. In this series we found that FDG-PET/CT discovered M1b disease in 4 (8%) patients but was also falsely positive in 4 (8%) patients. The results of Z0060 might provide answers as to the staging advantages provided by FDG-PET for M1 disease and balance them against the increased cost and morbidity of investigating false-positive results.
| Complete Responders |
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There are strengths and weaknesses to our study. Most of the previous studies evaluate the accuracy of a single modality over a long time period. This study offers a comparison of CT, EUS-FNA, and FDG-PET/CT in the same patient population over a short 2-year period using the best currently available technology and experienced readers. This might minimize confounders because of alterations in clinician experience, assignment of stage by multiple clinicians, and changes in technology. However, our study has a relatively small sample size, has been performed in a single institution only by one surgeon, and has only 3 patients with T4 disease, 5 with proved M1a disease, and 6 with M1b disease. Moreover, the strict entry criteria to this study, which required biopsy proof of progressive disease, eliminated 9 patients. Most of these patients had EUS-FNA that showed T4 nonresectable tumors, but because there was no pathologic proof of T4 disease (these patients could have all been in pathologic T0 stage), they were not included in this study. This rigid design might have negatively affected the true benefit of EUS-FNA. A multi-institutional trial is needed.
| Recommendations |
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| Conclusion |
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| Discussion |
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First, I have some questions pertaining to the details of PET scanning. Your patients all underwent PET scanning, as you pointed out, with the integrated PET/CT system. Presumably, this is what allowed the differentiation of the T stage of the tumor. Can you elaborate on how exactly PET/CT was used to determine the T stage, and in the absence of a fusion CT/PET system at a center, is it still possible to use PET scanning to define T stage?
Second, why were all 3 tests so poor at accurately identifying T4 tumors? And because the 3 patients with T4 tumors in your series all underwent successful surgical resection anyway, how important is it to determine the T stage after neoadjuvant therapy?
Third, all 3 tests were associated with false-positive and false-negative assessment of nodal metastases, and this is in the setting of a study within an academic center. Out in the real world, accuracy rates are almost certain to be lower. What do you believe are acceptable accuracy rates when the results are going to be used for important patient management decisions?
Fourth, recent studies with either minimally invasive staging techniques or EUS-FNA have suggested that complete pathologic response rates with neoadjuvant therapy are lower in patients with pretherapy pathologically confirmed N1 disease. What percentage of patients with pathologically confirmed N1 disease had a complete response to neoadjuvant therapy in your series?
Fifth, why was the positive predictive value for complete response so poor and not significantly different with the 3 modalities? You did not present that; instead, you focused on negative predictive value. But is the positive predictive value not more important in this circumstance?
Sixth, there were 4 patients with true-positive results with systemic metastases found by fusion CT/PET scanning after neoadjuvant therapy, but there were 8 patients with false-positive or false-negative scan results. Because the number of false positive and false-negative PET scan results exceeded the true-positive results, is PET even worthwhile for assessing systemic metastatic disease after neoadjuvant therapy, or should we just be using CT, especially because most metastases were either in the lung or the liver, areas that are very well seen with computed axial tomography?
Lastly, do you have any information on the relative cost or cost/benefit ratio of each of these tests? And if you were at a center and had only the option of picking one test, which one would it be?
Dr Cerfolio. Thank you very much, Dr DeMeester. For times sake, we might have to finish some of these questions over a beer later, but I will try to answer them all as quickly and succinctly as possible.
Your first question was as follows: Can PET tell us about T status, as opposed to PET/CT? I do not think it can. I think with the enhanced spatial resolution of integrated PET/CT, you can at least get an idea of the T status, like you can on a computed axial tomographic scan, but as we all know, it is not very good. The esophagus looks thickened. You do not know what is residual cancer and what is fibrotic, but neither does the endosonographer with EUS, as we found out in this study.
Second, you asked about the patients with T4 disease and why the modalities were so poor with that. I cannot tell you. Perhaps because this is a surgical series that required resection as an entry criterion, some T4 diseases were eliminated. Perhaps there is a difference between respectable T4 disease (thought to be T3 disease in this series or we probably would not have offered surgical intervention) than nonresectable T4 disease. The very rigorous design meant that 9 patients were eliminated; 7 of them had EUS criteria that showed T4 disease. Because I could not prove that the EUS was right, I could not include them in this study. They could have been complete responders, and the endosonographer could have been wrong, but those patients were not included.
The third question was about the false-positive and false-negative results for nodal status. This is an important finding, especially for our medical colleagues. Just because a node is positive on a CT scan or PET scan, whether a patient has lung cancer or esophageal cancer, only means a biopsy of that lesion is required. Because EUS oftentimes cannot traverse the primary to get to the peritumoral lymph nodes to assess the node and because the echogenicity of the node after radiation and chemotherapy might not be a good predictor of malignancy or benignancy as it is before chemoradiotherapy, once must keep this in mind when interpreting the results of the restaging tests.
The fourth question concerns the complete responders. There were 15 complete responders; 8 patients were initially staged as having N1 disease, and 7 patients had N0 disease. A high number had biopsy-proved N1 disease initially.
The fifth question concerns why we reported the high negative predictive value and not the low positive predictive value. Actually, we report both, but the positive predictive value reflects prevalence of disease, and for this article, with a relatively small number of patients, it might not be as important.
Your sixth question concerns the role of PET for M1b disease. As we all know, there is a Z60 multi-institutional trial going on that is better able and equipped to accurately answer that question than this current series. We have placed more than 25 patients in that trial. One has to consider the cost of chasing after false-positive results with extra scans and the anxiety that it causes patients versus identifying new M1b disease and avoiding unhelpful resections. I believe it is worthwhile, but I await the results of the Z60.
Finally, as to the costs and what we recommend, as I showed in one of the slides, we recommend an integrated PET/CT scan. Not only does it better identify N1 disease than EUS but it also allows one to generate the change in maxSUV, which we believe is an important predictor of pathologic response. Our future is clearly PET/CT and not PET, and I think that is what all of us will have, at least in North America.
Dr Richard Whyte (Stanford, Calif). I have one quick question. You ran through some of those slides very quickly, but I think somewhere there you said that patients with a complete response benefit from an operation.
Dr Cerfolio. Thank you. I said "might" benefit the most from resection, although some believe they might not even require resection.
Dr Whyte. "Might" benefit. I wanted you to expound on that a little bit because if you really have a pathologic compelte response, do you benefit from an operation at all?
Dr Cerfolio. That is a great question and one that requires a prospective randomized trial to accurately answer. What you are saying is what we just talked about last week at one of our conferences, and that is the question of whether a patient who has a complete response benefits from esophagectomy? The real question in the past has been how one knows who is a complete responder without resecting them? I believe that we now have presented data with the maxSUVs as a way of getting a good idea of who these patients are. It is not the absolute value of the repeat PET scan. It is the percentage decrease of the maxSUV. In our article on lung cancer, which is coming out in Annals later this year, we found it was a decrease of greater than 80% that predicted a complete response. In this study it was a decrease of about 50% or 60% as a good predictor of complete response. Now for the first time, maybe we can ethically do that study and randomize patients with a significant decrease in the maxSUV and who are undergoing a repeat EUS and CT scan that show a complete response and randomize these patients to observation or resection. Until that study is done, I cannot fully answer your question. At least now we have a way to identify potential patients for the study.
Dr Stephen Yang (Baltimore, Md). Just to follow up on Richs comment, how many patients had a negative CT scan result and a negative PET/CT scan result? And when you present those data to the patientthe CT result is negative and the PET result is negativehow do you convince them to go on for a surgical operation?
Dr Cerfolio. Thank you. Well, I think of that up front, and therefore I tell them before they get their treatment that I have no data that even if they have a wonderful response that they should not undergo an operation. Thus I have them geared up for it preoperatively. We tell them we hope and pray that they get a great response, but they might not benefit from that without esophagectomy. I tell them I do not have definitive data to prove that, but that is my opinion and my belief. We have had 3 patients refuse operations because of this perceived clinical complete response, and all 3 have come back within 12 months with recurrent local disease and 1 with M1b disease. Until I see some data otherwise, that is practice and is what I am going to continue to tell them. I do not see why esophagectomy would be different from other cancers. If one can offer a safe operation and completely resect all disease, I believe that is best.
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