Metastases from non-small cell lung cancer: mediastinal staging in the 1990s--meta-analytic comparison of PET and CT

Imaging with F-18 FDG PET is superior to Tl-201 SPECT in the staging of non-small cell lung cancer for radical radiation therapy

Thallium-201 (Tl-201) single photon emission computed tomography (SPECT) is funded for evaluation of malignancy in Australia and may have utility for staging of non-small cell lung cancer (NSCLC) if CT results are equivocal. Fluorine-18 fluorodeoxyglucose (F-18 FDG) positron emission tomography (PET) is superior to CT for staging NSCLC but is more expensive and less widely available than Tl-201 SPECT. Therefore, these techniques were prospectively compared in 27 radical radiation therapy candidates. Patients were allocated a conventional, PET and Tl-201 stage. Tumour to background ratios (TBR) were recorded for the primary on both techniques. Metastatic disease was confirmed by surgical pathology, serial imaging or clinical follow up. Tumour to background ratios were consistently higher for FDG PET than Tl-201 SPECT (P < 0.0001). Positron emission tomography detected all known primary tumours but Tl-201 failed to image four primary tumours (15%). In 10 of 18 cases of discordance between PET and Tl-201 SPECT regarding stage, corroboration was available from pathology or disease progression. Positron emission tomography was shown to have a 100% positive predictive value, including all three patients with PET-detected distant metastases (P=0.002). Results indicate that PET is superior to Tl-201 SPECT scanning in the staging of NSCLC for radical radiation therapy, and that the low sensitivity for detection of local and metastatic disease is likely to limit the clinical impact and cost-effectiveness of this technique despite its lower cost.

Positron emission tomography in the diagnosis and staging of lung cancer: a systematic, quantitative review

Lung cancer is the cause of 32% of all male cancer deaths and 25% of all female cancer deaths. Because the prognosis depends on early diagnosis and staging, continuous evaluation of the diagnostic tools available is important. The aim of this study was to assess the diagnostic value of dedicated positron emission tomography (PET) and gamma-camera PET in the diagnostic investigation of non-small-cell lung cancer (NSCLC). A systematic literature search was carried out in the MEDLINE and EMBASE databases and the Cochrane Controlled Trials Register. We identified 55 original works on the diagnostic performance of PET with fluorodeoxyglucose in the investigation of NSCLC. For diagnosis of NSCLC, the mean sensitivities and specificities were, respectively, 0.96 (SE 0.01) and 0.78 (0.03) for dedicated PET, and 0.92 (0.04) and 0.86 (0.04) for gamma-camera PET. In the mediastinal staging of NSCLC, the results were 0.83 (0.02) and 0.96 (0.01) for dedicated PET and 0.81 (0.04) and 0.95 (0.02) for ganuna-camera PET. We conclude that dedicated PET could be a valuable tool in the diagnosis and staging of NSCLC. However, studies of populations with a lower prevalence of NSCLC are recommended.

[Interest in 18-FDG positron emission tomography in radiotherapy planning: example of lung cancer radiotherapy]

18 FDG positon emission tomography provides metabolic images and allows better local and metastatic staging than radiologic methods. A best cartography of node involvement and a best delineation of the tumor zone should allow an optimal radiotherapy. Lung cancer is a good example of the interest of this new method.

[Imaging of lung cancer: role of radiology]

The aim of this review is to discuss the imaging available for diagnostic, therapy and follow-up for lung cancer management.

Positron emission tomography: brain tumors and lung cancer

F-18 fluorodeoxyglucose positron emission tomography is a uniquely powerful diagnostic tool that noninvasively provides information that is critical to appropriate clinical management of patients with non-small cell lung cancer. Not only does the functional information provided by PET complement and clarify the anatomic information supplied by CT and MR imaging, but the superior sensitivity and negative predictive value of PET allow for improved accuracy in diagnosis, prognosis, staging, and monitoring the effects of treatment. With better information at their disposal, clinicians and patients are able to make better-informed decisions, contributing to more appropriate and more cost-effective medical care. Truly, FDG-PET has earned its place as the new standard of care in imaging non-small cell lung cancer.

Impact of FDG-labelled positron emission tomography imaging on the management of non-small-cell lung cancer

Lung cancer is currently the leading cause of cancer-related death in both men and women in most Western countries. Although 5-year survival rates have doubled from 1960s, they are low compared with survival rates for other cancer types. Tumour stage is the strongest prognostic factor and the most important parameter that guides treatment decision making. Metabolic imaging with fluorodeoxyglucose-labelled positron emission tomography (FDG-PET) has proved superior to conventional imaging for staging of non-small-cell lung cancer. This new imaging modality permits more accurate planning of treatment with surgery and radiotherapy and provides information of greater prognostic significance than what can be obtained with conventional approaches. FDG-PET has been approved in the USA and the UK as a basic and invaluable tool in the management of lung cancer. This paper reviews current trends in clinical practice on the applications of FDG-PET in the management of non-small-cell lung cancer.

F-18 fluorodeoxyglucose positron emission tomography staging in radical radiotherapy candidates with nonsmall cell lung carcinoma: powerful correlation with survival and high impact on treatment

BACKGROUND

Successful treatment of nonsmall cell lung carcinoma (NSCLC) with radical radiotherapy (RT) requires accurate delineation of tumor extent. Conventional computed tomography-based noninvasive staging often estimates intrathoracic thoracic tumor extent incorrectly and fails to detect distant metastasis. High sensitivity and specificity are reported for F-18 fluorodeoxyglucose (FDG) positron emission tomography (PET) staging in potentially resectable NSCLC. The authors investigated FDG-PET staging in radical RT candidates with unresectable NSCLC.

METHODS

The authors prospectively studied 153 consecutive patients with unresectable NSCLC who were candidates for radical RT after conventional staging and had PET scans. Patients were allocated both "before PET" and "after PET" stages. Subsequent management was recorded. Survival analysis was used to compare validity of pre-PET and post-PET staging.

RESULTS

After PET, 107 patients (70%) actually received radical therapies (radical RT with or without concurrent chemotherapy, n = 102; radical surgery, n = 5); 46 patients (30%) received palliative treatment because of PET-detected distant metastasis (n = 28; 18%) or extensive locoregional disease (n = 18; 12%). Palliative therapies were RT (n = 33), chemotherapy (n = 12), or supportive care (n = 1). All five surgically treated patients underwent potentially curative resections after downstaging by PET. For radically treated patients, post-PET stage (P = 0.0041) but not pre-PET stage (P = 0.19) was strongly associated with survival. Radically treated patients survived longer than those treated palliatively (P = 0.02; 1-year survival, 69% and 44%, respectively; 2-year survival, 44% radical; no palliative patients had 2-yr follow-up).

CONCLUSIONS

Positron emission tomography-assisted staging detected unsuspected metastasis in 20%, strongly influenced choice of treatment strategy, frequently impacted RT planning, and was a powerful predictor of survival. Potential impact of FDG-PET is even greater in radical RT candidates with NSCLC than in surgical candidates.

A comparison of MRI and PET scanning in surgically staged loco-regionally advanced cervical cancer: potential impact on treatment

The aim of this study was to assess whether positron emission tomography (PET) or magnetic resonance imaging (MRI) could obviate the need for surgical staging in patients with locally advanced cervical carcinoma being planned for radiotherapy (RT). Imaging findings were compared to surgical staging in 27 patients including three with recent resection of the primary tumor. Both PET and MRI visualized all 24 residual cervical tumors. Primary tumor volume, as measured by MRI scan, ranged from 1.25 cc to 140 cc. In 24 patients evaluable for pelvic nodal status, PET had sensitivity, specificity, and positive and negative predictive values of 83%, 92%, 91% and 85%, respectively, with 88% accuracy. MRI detected only six in 12 (50%) patients with confirmed pelvic nodal disease, all of which were also seen by CT and PET, with an overall accuracy of 75%. PET detected only four in seven (57%) cases with confirmed para-aortic (PA) involvement. All histologically confirmed sites not visualized on PET were <1 cm. Without surgical staging, six in 10 (60%) patients with histologically proven pelvic nodal disease would not have received pelvic boost if guided by MRI alone, compared to two in 10 (20%) patients guided by PET alone or in combination with MRI. All four patients with positive PA on PET were confirmed on histology or clinical follow-up, including one case that proved to be a false negative one on surgery. However, in three cases, PET would have yielded an inadequate radiation volume. In conclusion, the positive predictive value of PET in the pelvis and para-aortic region appears sufficient to obviate lymph nodal sampling, but sampling is still required to exclude small-volume disease cranial to sites of abnormality on PET. MRI has insufficient accuracy for nodal staging to impact management.

The fusion of anatomic and physiologic imaging in the management of patients with cancer

Imaging is of major clinical importance in the noninvasive evaluation and management of patients with cancer. Computed tomography (CT) and other anatomic imaging modalities, such as magnetic resonance imaging (MRI) or ultrasound, have a high diagnostic ability by visualizing lesion morphology and by providing the exact localization of malignant sites. Nuclear medicine provides information on the function and metabolism of cancer. Over the last decade, there have been numerous attempts to combine data obtained from different imaging techniques. Fused images of nuclear medicine and CT (or to a lesser extent, MRI) overcome the inherent limitations of both modalities. Valuable physiologic information benefits from a precise topographic localization. Coregistered data have been shown to be useful in the evaluation of patients with cancer at diagnosis and staging, in monitoring the response to treatment, and during follow up, for early detection of recurrence. Time-consuming and difficult realignment and computation for fusion of independent studies have, until now, limited the use of registration techniques to pilot studies performed in a small number of patients. The development of the new technology of single photon emission computed tomography/CT and positron emission tomography/CT that allows for combined functional and anatomic data acquisition has the potential to make fusion an everyday clinical tool.

High rate of detection of unsuspected distant metastases by pet in apparent stage III non-small-cell lung cancer: implications for radical radiation therapy

PURPOSE

Most radical radiotherapy (RT) candidates with non-small-cell lung cancer (NSCLC) have Stage III disease and ultimately die with distant metastases. We tested the hypothesis that positron emission tomography (PET) using 18-F fluorodeoxyglucose (FDG) would detect more unsuspected metastases in apparent Stage III disease than in Stages I-II.

METHODS AND MATERIALS

Staging FDG-PET was performed for 167 NSCLC patients, with Stage I-III by conventional workup, who were candidates for curative therapy with surgery (n = 8), radical chemo/RT or RT (n = 156), or preoperative chemo/RT (n = 3). Each patient was allocated a conventional "pre-PET stage" and a "post-PET stage" that relied on PET when discordance with conventional staging occurred.

RESULTS

Stage distribution pre-PET was n = 39 (Stage I), n = 28 (Stage II), and n = 100 (Stage III). In 32 patients (19%), PET detected distant metastasis, most commonly abdominal with 17 cases (adrenal, n = 7; liver, n = 4; other, n = 6). Other sites included lung (n = 10) and bone (n = 6). PET-detected metastasis increased with increasing pre-PET stage from I (7.5%) through II (18%) to III (24%, p = 0.016), and, in particular, was significantly higher in Stage III (p = 0.039). Biopsy confirmation was not routine, but progression occurred at PET-detected metastatic sites or other metastatic sites in all but 3 of the 32 patients by last review.

CONCLUSION

PET staging is recommended for radical RT candidates with NSCLC. The highest yield of unexpected distant metastases is observed in Stage III.

The role of positron emission tomography with 18F-fluoro-2-deoxy-D-glucose in respiratory oncology

In the past 5 yrs, positron emission tomography (PET) with 18F-fluoro-2-deoxy-D-glucose (FDG) has become an important imaging modality in lung cancer patients. At this time, the indication of FDG-PET as a complimentary tool to computed tomography in the diagnosis and staging of nonsmall cell lung cancer has gradually gained more widespread acceptance and also reimbursement in many European countries. This review focuses on the data of FDG-PET in the diagnosis of lung nodules and masses, and in locoregional and extrathoracic staging of nonsmall cell lung cancer. Emphasis is put on the potential clinical implementation of the currently available FDG-PET data. The use of FDG-PET in these indications now needs further validation in large-scale multicentre randomized studies, focusing mainly on treatment outcome parameters, survival and cost-efficacy. Interesting findings with 18F-fluoro-2-deoxy-D-glucose-positron emission tomography have also been reported for the evaluation of response to radio- or chemotherapy, in radiotherapy planning, recurrence detection and assessment of prognosis. Finally, a whole new field of application of positron emission tomography in molecular biology, using new radiopharmaceuticals, is under extensive investigation.

Clinical role of positron emission tomography in oncology

Positron emission tomography (PET) is now in routine use in oncology, through the success of metabolic imaging, mainly with fluorodeoxyglucose (FDG). Clear benefit is obtained with FDG PET in the assessment of patients with recurrent or residual disease, especially colorectal cancer and lymphoma. Preoperative staging of non-small-cell lung cancer with FDG PET is of proven benefit. Staging and restaging of patients with melanoma of stage II or greater is useful, and FDG PET has also been successfully used to investigate single pulmonary nodules. Tumour grading has been assessed, especially in the brain, but an important and emerging indication is the evaluation of tumour response with PET. Rapid decline of FDG uptake has been observed in responsive cancers. Further advances are being made with other fluorine-18-labelled and generator-based PET tracers, the only ones that can be used in units without dedicated cyclotrons.

Toward less futile surgery in non-small cell lung cancer? A randomized clinical trial to evaluate the cost-effectiveness of positron emission tomography

Non-small cell lung cancer can be cured if the patient is medically operable and the tumor resectable. Current diagnostic strategies are aimed to detect tumor deposits that preclude resection with curative intent. However, these strategies are rather inefficient, resulting in a large number of futile invasive procedures. In the early 1990s positron emission tomography (PET) showed promising results at its introduction in the clinic, especially in oncology. A large number of accuracy studies have reported that PET is superior to conventional imaging. However, whether PET ultimately improves patient outcome should ideally be assessed by means of a randomized controlled trial. No such design has been applied to evaluate PET in oncology so far. The PLUS study was designed to compare the current strategy of conventional methods with a strategy where PET was added after completion of noninvasive techniques. Patients considered operable by the physician at this point were then randomly assigned to PET and further consequences or to standard procedures of mediastinoscopy or thoracotomy. Primary outcome events were futile thoracotomies. The trial randomized 188 patients from nine hospitals in 1 year. Patient enrollment has been stopped and data collection is in progress. The results will be published in 2001. Control Clin Trials 2001;22:89-98

The Role of Positron Emission Tomography in Evaluating Mediastinal Lymph Node Metastases in Non–Small-Cell Lung Cancer

Positron emission tomography (PET) is a modality that differentiates malignant from benign processes based upon metabolism rather than anatomy. A number of studies have confirmed improved accuracy of PET over computed tomography (CT), but until a few recent studies, most had failed to include satisfactory histologic confirmation. The objective of this study was to compare PET and CT to histologic staging of the mediastinum in patients with non-small-cell lung cancer (NSCLC). Histologic examination of mediastinal lymph nodes (MLNs) was performed on 40 patients with NSCLC at mediastinoscopy and/or at surgical resection. PET scans were interpreted by one of two nuclear medicine physicians, blinded to histology, using CT scans for anatomic localization. CT scans were independently evaluated for mediastinal lymphadenopathy. The overall accuracy, sensitivity, and specificity of PET were 78% (31 of 40), 67% (four of six), and 79% (27 of 34), respectively. The overall accuracy, sensitivity, and specificity of CT were 68% (27 of 40), 50% (three of six), and 71% (24 of 34), respectively. PET was superior to CT at correctly identifying mediastinal nodal metastases; however, both modalities were inferior to the gold standard of surgical staging. PET is more accurate than CT in staging the mediastinum of patients with NSCLC. PET failed to identify lymph node metastasis in 33% of patients with histologically proven MLN involvement, and false positives were present in 15%. At present, mediastinoscopy should remain the standard of care for preoperative mediastinal staging for NSCLC.

Biological features and preoperative evaluation of mediastinal nodal status in non-small cell lung cancer

BACKGROUND

To examine whether biological features of primary tumor can help preoperative evaluation of mediastinal nodal status in non-small cell lung cancer.

METHODS

A total of 450 patients who underwent tumor resection and mediastinal dissection were reviewed. p53 status and proliferative fraction (PI) were evaluated immunohistochemically.

RESULTS

The accuracy of preoperative evaluation of mediastinal nodal status with computed tomography (CT) was 72.2%; mediastinal nodal metastases had not been revealed until operation in 59 patients (13.1%) (false-negative), and no metastasis was revealed in 66 patients (14.7%) although mediastinal nodal enlargement had been demonstrated by CT (false-positive). The number of false-negative patients was significantly larger when p53 aberrant expression was positive or when PI was higher. Combined with p53 status and PI, there were 27 false-negatives (24.1%) among patients with aberrant p53 expression and higher PI, whereas only two false-negatives (1.5%) among those with negative p53 expression and lower PI.

CONCLUSIONS

Mediastinoscopy may be recommended for tumor showing aberrant p53 expression and higher PI, even when CT demonstrates no mediastinal nodal enlargement.

Counterpoint: better radiation treatment of non-small cell lung cancer using new techniques without elective nodal irradiation

The treatment of non-small cell lung cancer has continued to evolve with the advent of improved staging technologies, chemotherapeutic agents, and methods of radiation delivery. Treatment of clinically uninvolved, regional lymph nodes historically has been delivered in the attempt to cover unseen disease, reduce regional failure, and improve survival. None of these suppositions has been tested nor are they supported by data. With enhanced staging using modalities like positron emission tomography and esophageal ultrasonography, treatment portals can be designed to encompass known disease with greater accuracy and confidence. Data for early-stage non-small cell lung cancer is now increasing and strongly suggest that eliminating elective nodal irradiation does not result in a high incidence of nodal relapse and does not compromise survival. Three-dimensional conformal radiotherapy incorporates better targeting and beam directions to effect smaller treatment volumes that include only clinically evident disease. It provides treatment techniques that maximize tumor dose and minimize normal tissue toxicity. Using smaller fields that do not incorporate elective nodal regions may allow higher doses, and these may help improve local control and survival in a disease where current results are unacceptable.

Factors associated with false-positive staging of lung cancer by positron emission tomography

BACKGROUND

Positron emission tomography imaging is gaining popularity as a noninvasive staging tool in non-small cell lung cancer. Nonmalignant processes can also affect radio-tracer uptake. This study seeks to identify factors associated with false-positive staging of mediastinal metastases.

METHODS

A retrospective review was performed of 100 patients with early stage non-small cell lung cancer referred for positron emission tomography scan evaluation. All had pathologic confirmation of their disease. Positron emission tomography scans, radiology records, operative reports, and pathology results were reviewed. Patients with positron emission tomography scans interpreted as positive for mediastinal involvement and negative pathology at operation were selected.

RESULTS

Seven patients were found to have a false-positive positron emission tomography evaluation for mediastinal metastases. All but 1 patient had a concurrent inflammatory process or an anatomic factor associated with the false positive. The sensitivity and specificity in detecting involved mediastinal nodes was 87.5% and 90.7%, respectively. The negative predictive value was 95.8%.

CONCLUSIONS

Although positron emission tomography has been established as an accurate modality to stage non-small cell lung cancer, false-positive evaluation of mediastinal metastases can occur in the setting of concurrent inflammatory lung diseases or for centrally located tumors. Pathologic evaluation of mediastinal disease should be pursued whenever suggested by a positive positron emission tomography scan especially in the face of those factors described.

Clinical imaging of cancer metastasis

Tumour imaging is an essential part of the practice of oncology, with a crucial role in screening programmes and in diagnosis and staging of established disease. Furthermore, the assessment of tumour size by imaging, usually with computer tomography (CT) scanning, is a key component in determining the tumour response to therapy both in clinical trials and in daily oncology practice. Techniques such as CT, ultrasound (US) and magnetic resonance imaging (MRI) provide high resolution anatomical images with detailed structural information. However, these imaging modalities yield limited functional information on the tumour tissues and often cannot distinguish residual disease from non-viable or necrotic tumour masses, nor can they detect minimal residual disease. In contrast, radiopharmaceutical imaging and, in particular, positron emission tomography (PET) can give some functional information about the underlying tissues. The possibility of refining these techniques and also the emergence of newer imaging modalities that can detect changes in cancers at the physiological, cellular or molecular levels, gives rise to the notion that these methods will have implications for drug development strategies and also future clinical management. In this review, we briefly discuss the current role of imaging in clinical practice, describe some of the advances in imaging modalities currently undergoing evaluation, and speculate on the future role of these techniques in developmental therapeutics programmes.

Primary non-small-cell lung cancer: determining the suitability of the patient and tumor for resection

Choosing resective surgery for patients with bronchogenic carcinoma requires assessments of tumor suitability and patient suitability. Tumor suitability is largely dependent on the assessed stage of the tumor complex, based on characteristics of the primary tumor, detection of lymph node metastases, and detection of distant metastases. Imaging tests that assist in the determination of tumor stage include computed tomographic scans and positron emission tomographic (PET) scans. PET scans are more sensitive and specific than computed tomography. PET is also helpful in screening for distant metastases. Mediastinoscopy is required in most cases of mediastinal adenopathy. Patient suitability is assessed by predicting short-term surgical mortality, and the likelihood of crippling long-term respiratory failure. There is no single test that provides such information. Pulmonary function tests can be used to calculate the "predicted postoperative" function, and several algorithmic approaches have been devised to predict surgical risk. Assessments of regional pulmonary function are obtained with quantitative perfusion scintiscans. Cardiac function is also an important factor.

Nuclear medicine imaging of lung cancer

Although nuclear medicine imaging is still widely under-appreciated and underused by the medical and radiologic communities, FDG PET imaging and Tc 99m depreotide SPECT imaging are safe, cost-effective methods with advantages over CT and other imaging methods in the diagnosis and management of patients suspected or known to have lung cancer. Physicians involved in the care of these patients should familiarize themselves with both of these relatively new nuclear medicine imaging procedures. Both F-18 FDG PET imaging and Tc 99m depreotide SPECT imaging have a high degree of sensitivity, specificity, overall accuracy, and both PPV and NPV in the management of patients with a solitary pulmonary nodule. Nuclear imaging with either of these agents provides a noninvasive, cost-effective method to select patients for aggressive intervention without contributing to increased morbidity. There has not been a direct comparison of these two techniques in terms of their relative role and cost-effectiveness in the management of patients with a solitary pulmonary nodule. Both methods have incremental value over CT imaging in selecting patients with solitary pulmonary nodules either for invasive biopsy or for thoracotomy. To date, only FDG PET has been proved to have additional application in: 1. Improving the staging of patients by identifying or excluding mediastinal disease. Some authors are reluctant at the present time to deny patients an opportunity for curative resection based on the finding of foci of increased metabolism in the mediastinum (characterized by increased FDG activity) because there are occasional false-positive studies. They propose, however, that a negative study justifies a surgical approach (and an opportunity for cure) regardless of the findings on CT. 2. Evaluation of therapy and early detection of recurrence by using FDG PET imaging as a monitoring procedure. Tc 99m depreotide may have a role also in these other clinical indications for imaging in patients with lung carcinoma. It is too soon, however, to know if Tc 99m depreotide SPECT imaging, properly performed, can mimic the success of FDG PET in the detection or exclusion of mediastinal metastases, evaluating the response to therapy, and the early detection of recurrent disease during post-therapeutic monitoring.