Diagnostic value of positron emission tomography for detecting breast cancer

KSNM60 in Clinical Nuclear Oncology

Since the foundation of the Korean Society of Nuclear Medicine in 1961, clinical nuclear oncology has been a major part of clinical nuclear medicine in Korea. There are several important events for the development of clinical nuclear oncology in Korea. First, a scintillating type gamma camera was adopted in 1969, which enabled to perform modern oncological gamma imaging. Second, Tc-99 m generator was imported to Korea since 1979, which promoted the wide clinical use of gamma camera imaging by using various kinds of Tc-99 m labeled radiopharmaceuticals. Third, a gamma camera with single photon emission tomography (SPECT) capability was first installed in 1980, which has been used for various kinds of tumor SPECT imaging. Fourth, in 1994, clinical positron emission tomography (PET) scanner and cyclotron with a production of F-18 fluorodeoxyglucose were first installed in Korea. Fifth, Korean Board of Nuclear Medicine was established in 1995, which contributed in the education and manpower training of dedicated nuclear medicine physicians in Korea. Finally, an integrated PET/CT scanner was first installed in 2002. Since that, PET/CT imaging has been a major imaging tool in clinical nuclear oncology in Korea. In this review, a brief history of clinical nuclear oncology in Korea is described.

Is sentinel lymph node biopsy a viable alternative to complete axillary dissection following neoadjuvant chemotherapy in women with node-positive breast cancer at diagnosis? An updated meta-analysis involving 3,398 patients

BACKGROUND

The use of sentinel lymph node biopsy (SLNB) following neoadjuvant chemotherapy (NAC) in patients presenting with clinically positive lymph nodes remains controversial.

METHODS

A computer-aided search of the literature regarding SLNB in clinically node-positive breast cancer treated with NAC was carried out to identify the false negative rate (FNR), sentinel lymph node identification rate (IR), and axillary pathological complete response (pCR).

RESULTS

Nineteen articles were used in the analysis yielding 3,398 patients. The pooled estimate of the FNR was 13% and that of the IR was 91%. The adjusted pCR rate was 47%. A trend toward significance was observed with only clinical stage N1 (cN1) disease whereby clinical stage N1 was associated with an increased pCR rate when compared to N2 or N3 disease (P = .06).

CONCLUSIONS

SLNB after NAC in biopsy-proven node-positive patients results in reasonably acceptable FNR and IR, making it a valid alternative management strategy to axillary dissection. More refined patient selection and optimal techniques can improve the FNR and IR in this patient population.

An Amorphous Selenium Based Positron Emission Mammography Camera with Avalanche Gain

Early diagnosis of breast cancer is crucial for effective treatment, and the need exists for greater detection ability and specificity than possible by screening x-ray mammography (currently the primary imaging technique for the detection of breast lesions). Positron Emission Tomography (PET) using the radiotracer 2-[fluorine-18]-fluoro-2-deoxy-D-glucose (FDG) offers a noninvasive, highly sensitive method for the diagnosis of breast cancer. Images from PET contain unique metabolic information that is not available from anatomical imaging techniques. We propose a Positron Emission Mammography (PEM) imaging system that maintains the established high specificity of FDG PET while providing improved collection efficiency for the radiotracer signal and the potential for images with better spatial resolution. This PEM system will enable detection of lesions that are considerably smaller than those that can be visualized using whole body PET imaging.

The compact dual-head PEM camera will be based on an amorphous selenium (a-Se) avalanche photodetector and the scintillator lutetium oxyorthosilicate (LSO). The camera promises high collection efficiency by combining the fast scintillation light decay and high light yield of LSO with the excellent quantum efficiency, large avalanche gain, and rapid response time of a-Se. We have measured the gain and readout time of an 8 μm a-Se layer and demonstrated the feasibility of the proposed PEM camera.

Positron emission tomography (PET) for assessment of axillary lymph node status in early breast cancer: A systematic review and meta-analysis

PURPOSE

Sentinel lymph node biopsy (SLNB) and axillary lymph node dissection (ALND) are used to assess axillary nodal status in breast cancer, but are invasive procedures associated with morbidity, including lymphoedema. This systematic review evaluates the diagnostic accuracy of positron emission tomography (PET), with or without computed tomography (CT), for assessment of axillary nodes in early breast cancer.

METHODS

Eleven databases including MEDLINE, EMBASE and the Cochrane Library, plus research registers and conference proceedings, were searched in April 2009. Study quality was assessed using the QUality Assessment of Diagnostic Accuracy Studies (QUADAS) checklist. Sensitivity and specificity were meta-analysed using a bivariate random effects approach.

RESULTS

Across 26 studies evaluating PET or PET/CT (n = 2591 patients), mean sensitivity was 63% (95% CI: 52-74%; range 20-100%) and mean specificity 94% (95% CI: 91-96%; range 75-100%). Across 7 studies of PET/CT (n = 862), mean sensitivity was 56% (95% CI: 44-67%) and mean specificity 96% (90-99%). Across 19 studies of PET-only (n = 1729), mean sensitivity was 66% (50-79%) and mean specificity 93% (89-96%). Mean sensitivity was 11% (5-22%) for micrometastases (≤2 mm; five studies; n = 63), and 57% (47-66%) for macrometastases (>2 mm; four studies; n = 111).

CONCLUSIONS

PET had lower sensitivity and specificity than SLNB. Therefore, replacing SLNB with PET would avoid the adverse effects of SLNB, but lead to more false negative patients at risk of recurrence and more false positive patients undergoing unnecessary ALND. The present evidence does not support the routine use of PET or PET-CT for the assessment of the clinically negative axilla.

Breast cancer

Diagnostic imaging modalities utilized in the care of cancer patients must fulfill several requirements: they must diagnose and characterize tumors with high accuracy, must reliably stage and restage the disease, and should allow for monitoring the effects of therapeutic interventions on the course of the disease. They should impact management by guiding treating physicians to appropriate individualized treatment strategies. There is ample evidence that positron emission tomography (PET) and PET-computed tomography (CT) imaging can meet these requirements. This chapter discusses the role and contributions of PET and PET-CT imaging using (18)F-fluorodeoxyglucose in diagnosing, staging, restaging, and treatment monitoring of breast cancer. Novel molecular imaging probes and devices that have been developed and translated into early clinical research protocols are also introduced.

The Role of Lymphatic Mapping and Sentinel Lymph Node Biopsy in the Staging of Breast Cancer

The widespread application of sentinel lymph node biopsy in the evaluation of patients with breast cancer has allowed for the more limited, selective treatment of regional lymph nodes and decreased the number of complete regional dissections performed in patients without nodal metastases. Surgical excision and pathologic evaluation of nodes for metastases allow for reliable staging and prediction of additional lymph node metastases. Sentinel lymph node biopsy also enables a meticulous histologic evaluation of multiple sections augmented by immunohistochemical staining. The current role of sentinel lymph node biopsy in the staging of breast cancer and ongoing controversies relating to the procedure are discussed.

Is there a role for positron emission tomography in breast cancer staging?

Positron emission tomography (PET) with fluorine-18 fluorodeoxyglucose (FDG) is a radiotracer imaging method that is used in the care of patients with cancer. We conducted a nonsystematic review of the literature regarding the applicability of this technique in patients with breast cancer, encompassing the impact of FDG-PET on surgical management, including axillary node staging and sentinel lymph node biopsy; the use of FDG-PET in the evaluation of the primary tumor; the role of FDG-PET in the evaluation of distant metastases both at diagnosis and in the investigation of suspected recurrence; and the ability of FDG-PET to predict treatment response. FDG-PET is not sufficiently sensitive to replace histologic surgical staging of the axilla. Although FDG avidity of the primary tumor has been shown to be an unfavorable indicator, there is insufficient information to recommend its routine use for this indication. FDG-PET is more sensitive than conventional imaging in the detection of metastatic or recurrent disease, but the impact of increased sensitivity on patient care and outcome has not been demonstrated. The data regarding prediction of treatment response are insufficient to reach any conclusion. There are a number of prospective, adequately powered clinical trials currently in progress that should provide more definitive answers regarding the role, if any, of this technique in the management of patients with breast cancer.

Breast Cancer: Pre- and Postoperative Imaging for Staging

Mammography is considered the "gold standard" in the evaluation of the breast from an imaging perspective. Multiple studies have demonstrated the benefit of mammography in detecting smaller cancers, leading to identification of early-stage breast cancers, which largely accounts for decreased mortality from breast cancer and the increased rate of breast conservation. Identification of a suspicious lesion on a mammogram prompts further evaluation including additional mammographic views, ultrasound examination, and biopsy. Recently, MRI and positron emission tomography are being offered as adjuncts to the preoperative workup to better stage the patient; however, there is still controversy over the most appropriate use of these modalities.

Cost-effectiveness of positron emission tomography in breast cancer

PURPOSE

In this study, we used quantitative decision tree modeling to assess the cost-effectiveness of a positron emission tomography (PET)-based management scenario for breast cancer in Canada.

PROCEDURES

Two patient management scenarios were compared (with and without PET). A metaanalysis of studies for the accuracy of PET in staging breast cancer was conducted. Life expectancies were calculated. Management costs were determined from previous cost-effective analyses, management costs from our institutions, and recently published Canadian cost estimates of various procedures.

RESULTS

A cost savings of $695 per person is expected for the PET strategy, with an increase in life expectancy (7.4 days), when compared with the non-PET strategy. This cost savings remained in favor of the PET strategy when subjected to a sensitivity analysis.

CONCLUSIONS

The use of a PET management strategy for the staging of breast cancer is expected to remain economically viable in Canada under various economic conditions.

FDG PET positive lymph nodes are highly predictive of metastasis in breast cancer

AIM

To determine whether or not fluorodeoxyglucose positron emission tomography (FDG PET) imaging when positive could obviate the necessity for sentinel lymph node biopsy and for complete axillary node dissection in patients with breast cancer.

METHODS

A total of 80 female patients with a histological diagnosis of breast cancer and clinically negative axillary nodes underwent an FDG PET and sentinel lymph node biopsy (SLNB) or total axillary dissection for staging of axilla. Both SLNB and axillary dissection were performed in 72 patients, while eight patients had total axillary dissection without SLN biopsy.

RESULTS

Of the 80 patients, 36 had lymph node metastasis on histopathology. SLNB was positive for metastasis in 35 (97%) of 36 patients (29 macrometastasis and seven micrometastasis). In the patient with false negative SLNB, the lymph node was completely replaced by the tumour. The FDG PET was true positive in 16 of 36 patients (sensitivity, 44%). There were two false positive studies with FDG PET, resulting in a specificity of 95%. The positive predictive value and accuracy of FDG PET for the detection of axillary lymph node metastasis were 89% and 72%, respectively. Univariate analysis revealed that higher grade of tumour, increased size and number of axillary lymph nodes were significantly associated with positive FDG PET results for axillary staging.

CONCLUSION

FDG PET cannot replace histological staging using SLNB in patients with breast cancer. However, FDG PET has a high specificity and positive predictive value for staging of the axilla in these patients. The patients with higher grade of tumour, larger size and higher number of axillary lymph nodes may be considered for FDG PET scan for axillary staging.

The Value of FDG Positron Emission Tomography in the Management of Patients with Breast Cancer

Increasing experience with positron emission tomography (PET) scanning in breast cancer patients is revealing a significant role for this imaging modality. This report summarizes the experience of 2-[F18]fluoro-2-deoxy-D-glucose (FDG) PET scanning in 165 breast cancer patients from the BC Cancer Agency, British Columbia, Canada, and reviews the literature on this topic. Using the database at PETSCAN Vancouver, we identified imaged patients with a diagnosis of breast cancer. We then conducted a retrospective review of these patients' BC Cancer Agency charts to extract demographic and follow-up information. Between November 2000 and March 2003 we identified 165 patients with histologically confirmed breast cancer who had undergone PET scanning, were registered at the BC Cancer Agency, and had follow-up information. The median patient age was 52 years. The sensitivity of PET in detecting axillary metastases was 28%, and the specificity was 86%. At diagnosis, 5% of patients were diagnosed with distant metastases. In patients undergoing PET scanning because of suspected recurrence, the sensitivity and specificity for detecting recurrence were 89% and 88%, respectively. Distant metastases were demonstrated in 30% of patients who were thought only to have local-regional recurrence. The results suggest that there are two clinical situations in which PET appears to be particularly valuable. The first is in the evaluation of patients who are suspected of having a tumor recurrence. The other is in identifying patients with multifocal or distant sites of malignancy who otherwise appear to have an isolated, potentially curable, local-regional recurrence.

Fluorodeoxyglucose-PET in the management of breast cancer

FDG-PET can be helpful in the diagnosis of primary breast cancer, especially in patients with dense breast tissue, significant fibrocystic changes, fibrosis after radiotherapy, and inconclusive results from MR imaging and other imaging modalities. PET has a limited role in patients with very small tumors and with well-differentiated and lobular types of breast cancer. In preoperative staging, FDG-PET has a low sensitivity for detection of regional lymph node involvement. Also, current PET imaging techniques can easily miss micrometastases. FDG-PET, however, has high positive predictive value for the axillary lymph node involvement, especially patient with advanced tumors. Compared with conventional imaging modalities, FDG-PET provides high diagnostic accuracy in detecting recurrent or metastatic breast carcinoma. FDG-PET seems to be highly useful for monitoring response to therapeutic interventions. This technique can identify response to therapy earlier than any other imaging method currently available. Obviously, identification of nonresponding patients could greatly improve patient management by allowing termination of ineffective and toxic therapies.

The role of positron emission tomographic imaging in breast cancer

Studies have shown that deoxy-2-fluorodeoxyglucose ((18)FDG) positron emission tomography (PET) has limited value in detecting primary tumors and axillary lymph node involvement in breast cancer. PET is most successful when it is used to evaluate locally advanced breast tumors. Identification of smaller, earlier-stage tumors and noninvasive or lobular tumors has been suboptimal. Because of several factors, PET should not replace standard techniques for evaluation of breast cancer, especially for micrometastasis. However, PET can provide invaluable information about disease extent, recurrent disease, and distant metastases, and this information can affect treatment decisions. (18)FDG PET can also facilitate the differentiation of therapy responders from nonresponders, allowing treatment regimen changes at an earlier stage.

Positron emission tomography in the staging and management of breast cancer

Background

Breast cancer is the commonest cause of cancer death in women in the Western world, and imaging is essential in its diagnosis and staging. Metabolic imaging is a novel approach to improving the detection of cancers, as malignant transformation of cells is often associated with increased metabolic activity. This review assesses the possible role of positron emission tomography (PET) as a single non-invasive imaging modality to replace or complement current imaging and surgical practices in the diagnosis and staging of breast cancer.

Methods and results

A Medline search was performed and articles were cross-referenced with other relevant material. Evaluation of primary breast cancer with PET has shown a sensitivity of between 64 and 100 per cent and a specificity of 33–100 per cent; diagnostic accuracy appears to be related to tumour size. Difficulties arise in altered fluorodeoxyglucose uptake in lobular carcinoma, carcinoma in situ and benign inflammatory breast disease. In axillary staging, sensitivities of between 25 and 100 per cent have been reported, but with a false-negative of up to 20 per cent. In the assessment of distant metastasis and asymptomatic patients with raised levels of tumour markers, PET was superior to conventional imaging modalities.

Conclusion

PET is not a single diagnostic and staging tool that can replace current surgical, histological and radiological staging. Its main role in breast cancer lies in the investigation of metastatic disease and the evaluation of pathological response to various chemotherapeutic regimens.

Staging in patients with locoregionally recurrent breast cancer: current practice and prospects for positron emission tomography

The aim of this study was to describe the extent and yield of daily clinical practice when staging patients with a locoregional recurrence (LRR) of breast carcinoma and to explore the prospects for positron emission tomography (PET). The population-based Eindhoven Cancer Registry was used to select all breast cancer patients in the southeast of the Netherlands with a first episode of LRR between January 1, 1994 and June 30, 2000 (n = 175). Additional data concerning staging procedures and follow-up were collected from the medical records. Furthermore, we asked 77 physicians (response: 75%) about their opinions on staging procedures and actual treatment policy. At LRR presentation, 16% of patients were found to have distant metastases. An additional 24% were diagnosed with distant metastases within 18 months. The questionnaire revealed that 33% of clinicians thought that the sensitivity of conventional imaging techniques was too low. We tend to conclude that in daily clinical practice there is a need for more sensitive dissemination tests for patients with a LRR of breast cancer.

The choice of the correct imaging modality in breast cancer management

This brief overview discusses which of the diagnostic options are more reliable and effective for breast cancer imaging with a view to avoiding the unjustified use of techniques that are suboptimal. The technological development of diagnostic imaging has been very impressive, and both radiological (mammography, ultrasonography, computed tomography, magnetic resonance imaging) and nuclear medicine tools (bone scan, planar and SPECT scintigraphy, sentinel node biopsy, positron emission tomography) have helped to overcome past limitations in the detection of small lesions. Furthermore, new approaches have been developed that permit successful differential diagnosis of doubtful lesions and rapid identification of systemic metastases, and allow non-invasive characterisation of the biology of cancer tissue. There is evidence that these advances may have helped in optimising therapeutic strategies. Importantly, the metabolic information provided by nuclear medicine procedures may be combined with the anatomical data supplied by radiological techniques in order to assist in predicting tumour response, planning radiotherapy and monitoring patient outcome. It is difficult to formulate conclusive diagnostic guidelines for application in the work-up of breast cancer, because while the role of some examinations, such as mammography and ultrasonography, is well established, that of others, such as magnetic resonance imaging and positron emission tomography, is still a matter of debate. There is a need for further prospective evaluations with appropriate clinical trials designed to evaluate the impact of these approaches in improving survival and quality of life.

Role of positron emission tomography in the management of breast cancer

Positron emission tomography (PET) is an imaging modality that utilises tracers based on biologically important compounds and can be used to study in vivo tissue function. This article reviews the current status of PET imaging in breast disease. The positron emitting glucose analogue 18F-FDG is used to image tissue glycolysis and has been extensively evaluated. Studies have shown that 18F-FDG PET has a high sensitivity and specificity for the detection of primary breast cancers, however its use is not superior that of conventional imaging modalities. Considerable interest is now focussing on the application of PET to non-invasively determine the lymph node status of patients with breast cancer and to predict and evaluate tumour response to chemotherapy. Relatively low cost gamma camera systems are now available that are capable of PET imaging, and thus it may therefore be possible to perform PET imaging in the majority of hospitals.

Differential diagnosis of gallbladder cancer using positron emission tomography with fluorine-18-labeled fluoro-deoxyglucose (FDG-PET)

BACKGROUND AND OBJECTIVES

The purpose of this paper is to evaluate the utility of positron emission tomography (PET) with fluorine-18-labeled fluoro-deoxyglucose (FDG) in the preoperative differential diagnosis of gallbladder tumors. We performed PET studies of gallbladder tumors in order to predict the malignancy of these tumors preoperatively.

METHODS

Sixteen patients who had protuberant lesions in the gallbladder and who were scheduled to undergo surgery were studied with PET using FDG. Focally increased FDG uptake in the gallbladder region was considered malignant. The FDG-PET findings were compared with the histological findings of surgical pathology.

RESULTS

Sensitivity of FDG-PET was 75% (6/8 patients). One of two false-negative cases suffered from diabetes mellitus, and in the other case, the lesion was small. Specificity was 87.5% (7/8 patients). A case with xanthogranulomatous cholecystitis (XGC) was the only false-positive case.

CONCLUSIONS

FDG-PET may be able to provide important information for evaluating the malignancy of gallbladder tumors.

Measuring [(18)F]FDG uptake in breast cancer during chemotherapy: comparison of analytical methods

Over the years several analytical methods have been proposed for the measurement of glucose metabolism using fluorine-18 fluorodeoxyglucose ([(18)F]FDG) and positron emission tomography (PET). The purpose of this study was to evaluate which of these (often simplified) methods could potentially be used for clinical response monitoring studies in breast cancer. Prior to chemotherapy, dynamic [(18)F]FDG scans were performed in 20 women with locally advanced ( n=10) or metastasised ( n=10) breast cancer. Additional PET scans were acquired after 8 days ( n=8), and after one, three and six courses of chemotherapy ( n=18, 10 and 6, respectively). Non-linear regression (NLR) with the standard two tissue compartment model was used as the gold standard for measurement of [(18)F]FDG uptake and was compared with the following methods: Patlak graphical analysis, simplified kinetic method (SKM), SUV-based net influx constant ("Sadato" method), standard uptake value [normalised for weight, lean body mass (LBM) and body surface area (BSA), with and without corrections for glucose (g)], tumour to non-tumour ratio (TNT), 6P model and total lesion evaluation (TLE). Correlation coefficients between each analytical method and NLR were calculated using multilevel analysis. In addition, for the most promising methods (Patlak, SKM, SUV(LBMg) and SUV(BSAg)) it was explored whether correlation with NLR changed with different time points after the start of therapy. Three methods showed excellent correlation ( r>0.95) with NLR for the baseline scan: Patlak10-60 and Patlak10-45 ( r=0.98 and 0.97, respectively), SKM40-60 ( r=0.96) and SUV(LBMg) ( r=0.96). Good correlation was found between NLR and SUV-based net influx constant, TLE and SUV(BSAg) (0.90< r<0.95). The 6P model and TNT had the lowest correlation ( r<or=0.84). SUV was least accurate in predicting changes in [(18)F]FDG uptake over time during therapy. For all methods, correlation with NLR was significantly lower for bone metastases than for other (primary or metastatic) tumour lesions ( P<0.05). In conclusion, three methods with different degrees of complexity appear to be promising alternatives to NLR for measuring glucose metabolism in breast cancer: Patlak, SKM and SUV (normalised for LBM and with a correction for plasma glucose).

Positron emission tomography in diagnosis and management of invasive breast cancer: current status and future perspectives

[18F]fluorodeoxyglucose positron emission tomography (FDG-PET) is a metabolic imaging modality that has increasing applications in oncology, neurology, and cardiology. Among the oncology applications, breast cancer is one of the most extensively studied diseases. FDG-PET has been performed for diagnosis, staging, and restaging of invasive breast cancer and for monitoring responsiveness to therapies. At the present time, the results of FDG-PET in detection of primary breast cancer and axillary staging are mixed and inconclusive. However, results demonstrating the superiority of FDG-PET over anatomic imaging modalities in detection of distant metastasis, recurrence, and monitoring therapies are relatively well documented. These applications have been accepted by medical professionals and the public, as evidenced by a recent decision by the Centers for Medicare and Medicaid Services (formerly Health Care Financing Agency) to provide coverage for the procedure. Future trends in this exciting area include development of novel breast cancer-specific PET radiopharmaceuticals and use of dedicated breast PET technologies for scans of breast/axillary lesions. PET/computed tomography technology, which combines anatomic and molecular/biochemical information, is also rapidly proliferating and should help to further improve the management of patients with breast cancer. The role of FDG-PET in breast cancer is increasing and evolving, and this metabolic imaging modality, in conjunction with newer tracers and other anatomic imaging methods, should improve diagnosis and management of patients with breast cancer

The Role of 18F-FDG-PET in the Local/Regional Evaluation of Women with Breast Cancer

PURPOSE

In women with breast cancer, knowledge of the local/regional extent of the tumor is essential for staging, treatment planning, monitoring response to therapy, and follow-up. Positron emission tomography (PET) is an important imaging test which can detect tumor at multiple sites in women with breast cancer. We compared the ability of PET to provide a comprehensive view of the local/regional extent of tumor in women with stage I, II and stage III, IV breast cancer.

MATERIALS AND METHODS

Forty-six women with breast cancer underwent PET using 18F-FDG. 18FDG uptake in the breast primary tumor, associated skin, axillary and internal mammary lymph nodes, and the contralateral breast was determined qualitatively, and correlated with histologic, clinical and radiographic findings.

RESULTS

Twenty-four patients were premenopausal and 22 were postmenopausal, with the following distribution according to clinical stage: stage I--2 patients, stage II--16, stage III--16, stage IV--12 patients. Among stage I, II patients, the sensitivity for detection of the primary tumor was 83.3%, and for detection of axillary lymph node metastases was 42.9%. 18FDG-PET was negative for the breast skin, contralateral breast, and internal mammary lymph nodes in all stage I, II patients, in agreement with clinical and radiographic findings. Among 28 stage III, IV patients, the sensitivity of 18FDG-PET for detection of the primary tumor was 90.5%, and for detection of axillary lymph node metastases 83.3%. Fourteen patients had clinically advanced changes in the skin, and the sensitivity of PET for detection of skin changes was 76.9%. 18FDG-PET was positive in the internal mammary lymph nodes in 25.0%, and negative in the contralateral breast in all patients with stage III, IV breast cancer. 18FDG-PET was studied in 10 patients following neoadjuvant chemotherapy, and showed a strong correlation with clinical response, and with clinical and pathological findings post-treatment at multiple local/regional sites.

CONCLUSION

18FDG-PET can provide a comprehensive image of local/regional tumor in women with breast cancer. 18FDG-PET may play a greater role in women with stage III, IV breast cancer because of increased sensitivity and the increased involvement of multiple local/regional sites with tumor.

Should FDG PET be used to decide whether a patient with an abnormal mammogram or breast finding at physical examination should undergo biopsy?

RATIONALE AND OBJECTIVES

The purpose of this systematic review was to assess the performance of fluorodeoxyglucose positron emission tomography (PET) in the differential diagnosis of benign from malignant lesions among patients with abnormal mammograms or a palpable breast mass and to examine the effects of PET findings on patient care and health outcomes.

MATERIALS AND METHODS

A search of the MEDLINE and CancerLit databases covered articles entered between January 1966 and March 2001. Thirteen articles met the selection criteria. Each article was assessed for study quality characteristics. Meta-analysis was performed with a random effects model and a summary receiver operating characteristic curve.

RESULTS

A point on the summary receiver operating characteristic curve was selected that reflected average performance, with an estimated sensitivity of 89% and a specificity of 80%. When the prevalence of malignancy is 50%, 40% of all patients would benefit by avoiding the harm of a biopsy with negative biopsy results. The risk of a false-negative result, leading to delayed diagnosis and treatment, is 5.5%. The negative predictive value is 87.9%; thus, the false-negative risk is 12.1%. For a patient with a negative PET scan, a 12% chance of missed or delayed diagnosis of breast cancer is probably too high to make it worth the 88% chance of avoiding biopsy of a benign lesion.

CONCLUSION

The evidence does not favor the use of fluorodeoxyglucose PET to help decide whether to perform biopsy. Available studies omit a critical segment of the biopsy population with indeterminate mammograms or nonpalpable masses, for which no conclusions can be reached.

Positron emission tomography scanning: current and future applications

Whole-body positron emission tomography (PET) imaging with (18)F deoxyglucose (FDG) is a molecular imaging modality that detects metabolic alterations in tumor cells that are common to neoplastic cells. FDG-PET has recently been approved by the Health Care Finance Administration for Medicare reimbursement for diagnosing, staging, and restaging lung cancer, colorectal cancer, lymphoma, melanoma, head and neck cancer, and esophageal cancer. This review discusses the scientific evidence that led to the emergence of PET imaging as an accepted clinical tool in patients with solitary pulmonary nodules, lung cancer, colorectal cancer, melanoma, lymphoma, breast cancer, and other cancers. When possible, we compare the performance of PET to that of anatomical imaging. We discuss future clinical applications of this imaging modality.

Whole-body FDG-PET imaging in the management of patients with cancer

Fluorodeoxyglucose-positron emission tomography (FDG-PET) imaging is increasingly used for the management of patients with cancer. The technique is now well accepted by most physicians as an effective complement to the existing imaging modalities. For many malignancies, PET achieves high sensitivity and specificity. The critical role of this powerful technique is realized increasingly in the day-to-day practice of oncology. This is particularly true for the management of patients with non-small-cell lung cancer (NSCLC). The contribution of PET for the selection of patients eligible for curative treatments in this setting is well established. Convincing data also exist to support the use of PET for evaluating patients with recurrent colorectal carcinoma, for staging and restaging lymphomas, and for diagnosing recurrent thyroid carcinoma in the presence of elevated thyroglobulin and negative 131I scans. Other indications include staging of various recurrent malignancies, such as breast cancer, melanoma, and head and neck and gynecologic carcinomas. Existing data are limited for the determination of the impact of PET in certain malignancies, and further studies, which should include outcome information, will allow clarification of the role of this modality for such indications. Despite the small number of studies specifically designed to assess changes in management plans for some malignancies after performing PET the overall favorable results are encouraging enough at this time to include this modality as an essential element of the practice of modern oncology. Finally, the evolving role of PET imaging as a predictor of response after local or systemic treatment may add a major dimension to the application of this novel technique.

[(18F)-fluoro-2-deoxyglucose PET in imaging of gynecologic cancers]

Although gynaecological cancers are not currently part of the clinical indications in the French registration for [18F]-fluoro-2-deoxyglucose (FDG), various studies indicate in this context a potential clinical benefit of imaging with this radiopharmaceutical and PET, a new imaging modality that can be performed either with a dedicated machine or with a "hybrid" gamma-camera (CDET). The potential indications of FDG-PET in mammary, ovarian or cervical cancers are reviewed according to the diagnostic phase: screening, tumour characterisation, staging, therapeutic follow-up and search for recurrence. By pooling the published results, the accuracy of FDG-PET could be estimated with a reasonable precision in various clinical settings: characterisation of a breast tumour (598/696 = 86%), lymph node invasion in breast cancer (525/602 = 87%), recurrence of breast cancer (114/127 = 90%), characterisation of adnexal masses (130/176 = 78%), recurrence of ovarian cancer (152/172 = 88%), lymph node invasion in cervical cancer (98/103 = 95%). Authors also present original data concerning their experience of recurrence detection with CDET in breast or ovarian cancers. In 44 patients suspicious of recurrence of breast cancer, FDG-CDET sensitivity was 94%, specificity 82% and accuracy 91%; in 18 patients suspicious of recurrence of ovarian cancer, specificity, sensitivity and accuracy were 100%. The impact of dedicated PET and CDET examinations performed by our team during year 2000, led, according to 63 forms returned to us, to a modification of stage in 48% of breast cancers, 36% of ovarian cancers, 43% of cervical cancers and above all induced a modification in patients' management in respectively 69%, 64% and 60% of cases, more than the average rate in cancer patients which was 50%. No significant difference was observed between clinical impact of dedicated PET and CDET examinations.

Positron emission tomography imaging in oncology

The applications for FDG-PET imaging are rapidly growing and accepted in the field of oncology. FDG-PET imaging does not replace other imaging modalities, such as CT, but seems to be very helpful in specific situations where CT has known limitations, such as differentiation of benign from malignant indeterminate lesions on CT, differentiation of post-treatment changes versus recurrent tumor, differentiation of benign from malignant lymph nodes, and monitoring therapy. The biggest use of FDG-PET presently is in N and M staging of various body tumors. The addition of FDG-PET in the evaluation of oncologic patients in well-defined algorithms including a combination of imaging studies seems to be cost effective by accurately identifying patients who benefit from invasive procedures and saving unnecessary costly invasive procedures on patients who do not benefit from them. Although PET imaging may decrease the cost of health care by reducing the number of invasive procedures, implementation of clinical PET has been hindered by the high cost of the purchase, operation expenses, and maintenance of PET systems; the need for immediate access to a source of 18F (owing to the 110-minute half-life); and the limited reimbursement for clinical procedures by third-party payers. These combined factors have resulted in the development by manufacturers of hybrid gamma camera systems capable of performing positron imaging. These systems can be used to image conventional radiopharmaceuticals used in general nuclear medicine and positron-emitting radiopharmaceuticals. The performance of these camera-based PET systems has improved markedly over the past few years with the introduction of thicker NaI (T1) crystals, iterative reconstruction algorithms, and attenuation correction. These new developments in medical imaging instrumentation have contributed to the expansion of the number of cyclotrons, and have driven the concept of commercial FDG distribution centers.

Fluorodeoxyglucose positron emission tomography for detection of recurrent or metastatic breast cancer

Fluorodeoxyglucose-positron emission tomography (FDG-PET) is a noninvasive imaging technique capable of identifying primary tumors and metastases with high sensitivity and accuracy. The aim of this study was to evaluate the diagnostic accuracy of whole-body FDG-PET imaging for the detection of recurrent or metastatic breast cancer after surgery. Whole-body FDG-PET imaging was performed on 27 patients with suspected recurrent breast carcinoma. PET images were evaluated qualitatively for each patient and lesion. FDG-PET scans showed that there were 61 reference sites of malignant or benign lesions in 27 patients. In a patient-based analysis, FDG-PET scans correctly identified 16 of 17 patients with recurrent or metastatic disease and 8 of 10 without recurrence, resulting in a sensitivity, specificity, and accuracy of 94%, 80%, and 89%, respectively. In a lesion-based analysis, FDG-PET scans correctly identified 46 of 48 lesion sites with recurrent or metastatic disease and 11 of 13 without recurrence. The overall sensitivity, specificity, and accuracy for all lesion sites were 96%, 85%, and 93%, respectively. FDG-PET scans revealed unsuspected recurrent or metastatic diseases in 8 of 27 (30%) of patients and 11 of 20 (55%) distant metastatic lesions. In 13 patients treatment was altered by the outcome of the PET scan. We concluded that whole-body FDG-PET scan is a useful diagnostic imaging modality for detecting recurrent or metastatic breast carcinoma in patients suspected of having recurrent disease after primary surgery.

Axillary lymph node staging in breast cancer by 2-fluoro-2-deoxy-D-glucose-positron emission tomography: clinical evaluation and alternative management

BACKGROUND

Surgical removal of axillary lymph node and histologic examination for metastases are used to determine whether adjuvant treatment is necessary for patients with breast cancer. Axillary lymph node dissection (ALND) is a costly procedure associated with various side effects, and 80% or more of patients with tumors of 20 mm or less are lymph node negative and might avoid ALND. In this study, we evaluated whether an alternative, noninvasive method--i.e., positron emission tomography (PET) with 2-[(18)F]fluoro-2-deoxy-D-glucose (FDG)-- could be used to determine axillary lymph node status in patients with breast cancer.

METHODS

One hundred sixty-seven consecutive patients with breast cancers of 50 mm or less (range = 5-50 mm; mean = 21 mm) scheduled for complete ALND were studied preoperatively with FDG-PET, and then PET and pathology results from ALND were compared. All statistical tests were two-sided.

RESULTS

The overall sensitivity, specificity, and accuracy of lymph node staging with PET were 94.4% (PET detected 68 of 72 patients with axillary involvement; 95% confidence interval [CI] = 86.0% to 98.2%), 86.3% (82 of 95 patients without axillary involvement; 95% CI = 77.8% to 91.9%), and 89.8% (150 of 167 patients with breast cancer; 95% CI = 84.2% to 93.6%), respectively. Positive- and negative-predictive values were 84.0% (68 patients with histologically positive lymph nodes of 81 patients with positive FDG-PET scan; 95% CI = 74.2% to 90.5%) and 95.3% (82 patients with histologically negative lymph nodes of 86 patients with negative FDG-PET scan; 95% CI = 88.2% to 98.5%), respectively. When PET results for axillary metastasis were analyzed by tumor size, the diagnostic accuracy was similar for all groups (86.0%-94.2%), with higher sensitivity for tumors of 21-50 mm (98.0%) and higher specificity for tumors of 10 mm or less (87.8%), and the range was 93.5%-97.3% for negative-predictive values and 54.5%-94.1% for positive-predictive values. Among the 72 patients with axillary involvement, PET detected three or fewer metastatic lymph nodes in 27 (37.5%) patients, about 80% of whom had no clinically palpable axillary lymph nodes.

CONCLUSIONS

Noninvasive FDG-PET appears to be an accurate technique to predict axillary status in patients with breast cancer and thus to identify patients who might avoid ALND. These results should be confirmed in large multicenter studies.

18Fluorodeoxyglucose-positron emission tomography in the management of patients with suspected pancreatic cancer

OBJECTIVE

To assess the accuracy and clinical impact of 18fluorodeoxyglucose-positron emission tomography (18FDG-PET) on the management of patients with suspected primary or recurrent pancreatic adenocarcinoma, and to assess the utility of 18FDG-PET in grading tumor response to neoadjuvant chemoradiation.

SUMMARY BACKGROUND DATA

The diagnosis, staging, and treatment of pancreatic cancer remain difficult. Small primary tumors and hepatic metastases are often not well visualized by computed tomographic scanning (CT), resulting in a high incidence of nontherapeutic celiotomy and the frequent need for "blind resection." In addition, the distinction between local recurrence and nonspecific postoperative changes after resection can be difficult to ascertain on standard anatomic imaging. 18FDG-PET is a new imaging technique that takes advantage of increased glucose metabolism by tumor cells and may improve the diagnostic accuracy of preoperative studies for pancreatic adenocarcinoma.

METHODS

Eighty-one 18FDG-PET scans were obtained in 70 patients undergoing evaluation for suspected primary or recurrent pancreatic adenocarcinoma. Of this group, 65 underwent evaluation for suspected primary pancreatic cancer. Nine patients underwent 18FDG-PET imaging before and after neoadjuvant chemoradiation, and in eight patients 18FDG-PET scans were performed for possible recurrent adenocarcinoma after resection. The 18FDG-PET images were analyzed visually and semiquantitatively using the standard uptake ratio (SUR). The sensitivity and specificity of 18FDG-PET and CT were determined for evaluation of the preoperative diagnosis of primary pancreatic carcinoma, and the impact of 18FDG-PET on patient management was retrospectively assessed.

RESULTS

Among the 65 patients evaluated for primary tumor, 52 had proven pancreatic adenocarcinoma and 13 had benign lesions. 18FDG-PET had a higher sensitivity and specificity than CT in correctly diagnosing pancreatic carcinoma (92% and 85% vs. 65% and 62%). Eighteen patients (28%) had indeterminate or unrecognized pancreatic masses on CT clarified with 18FDG-PET. Seven patients (11%) had indeterminate or unrecognized metastatic disease clarified with 18FDG-PET. Overall, 18FDG-PET suggested potential alterations in clinical management in 28/65 patients (43%) with suspected primary pancreatic adenocarcinoma. Of the nine patients undergoing 18FDG-PET imaging before and after neoadjuvant chemoradiation, four had evidence of tumor regression by PET, three showed stable disease, and two showed tumor progression. CT was unable to detect any response to neoadjuvant therapy in this group. Eight patients had 18FDG-PET scans to evaluate suspected recurrent disease after resection. Four were noted to have new regions of 18FDG-uptake in the resection bed; four had evidence of new hepatic metastases. All proved to have metastatic pancreatic adenocarcinoma.

CONCLUSIONS

These data confirm that 18FDG-PET is useful in the evaluation of patients with suspected primary or recurrent pancreatic carcinoma. 18FDG-PET is more sensitive and specific than CT in the detection of small primary tumors and in the clarification of hepatic and distant metastases. 18FDG-PET was also of benefit in assessing response to neoadjuvant chemoradiation. Although 18FDG-PET cannot replace CT in defining local tumor resectability, the application of 18FDG-PET in addition to CT may alter clinical management in a significant fraction of patients with suspected pancreatic cancer.

Gamma emission imaging in the management of breast disorders

Breast cancer is the commonest malignancy to affect women. The malignant process may present clinicians with problems in establishing the diagnosis expeditiously, accurately staging the disease and assessing tumour response to primary systemic chemotherapy. Considerable recent interest has focused on the application of imaging techniques that utilize tumour-specific gamma-ray-emitting radiopharmaceuticals to resolve these problems. The wide availability of gamma camera systems makes single photon-imaging techniques, using radiopharmaceuticals incorporating conventional isotopes, attractive options. However, results concerning the detection of the primary breast cancer and the staging of axillary lymph nodes suggest that these techniques would appear to offer no significant advantages, when compared with those obtained using standard diagnostic methods. Dual gamma-ray-emission imaging by positron emission tomography (PET) may offer an alternative solution. Studies performed show that PET can accurately detect primary breast cancers, stage locoregional lymph nodes and visualize distant tumour metastases. Furthermore, PET may be able to monitor early tumour response to chemotherapy agents. It would appear, therefore, that dual gamma emission might have an important role to play in the management of patients with breast cancer.