18-FDG PET scan in the staging of recurrent melanoma: additional value and therapeutic impact

Positron Emission Tomography/Computed Tomography Transformation of Oncology: Melanoma and Skin Malignancies

Skin cancers are the most common cancers, with melanoma resulting in the highest cause of death in this category. Accurate clinical, histologic, and imaging staging with fludeoxyglucose positron emission tomography (FDG PET) is most important to guide patient management. Whilst surgical excision with clear margins is the gold-standard treatment for primary cutaneous melanoma, targeted therapies have generated remarkable and rapid clinical responses in melanoma, for which FDG PET also plays an important role in assessment of treatment response and post-therapy surveillance. Non-FDG PET tracers, advanced PET technology, and PET radiomics may potentially change the landscape of the utilization of PET in the imaging of patients with cutaneous malignancies.

Melanin-targeted [18F]-PFPN PET imaging for prognosticating patients with melanoma

PURPOSE

Positron emission tomography (PET) using [18F]-PFPN, a melanin-targeted imaging tracer, has excellent diagnostic performance in patients with melanoma. This study aimed to investigate its value in prognostication and determine predictors of progression-free survival (PFS) and overall survival (OS).

METHODS

We reviewed melanoma patients who underwent [18F]-PFPN and [18F]-FDG PET from February 2021 to July 2022. Clinical characteristics, follow-up data, and the following [18F]-PFPN PET parameters were recorded: maximum standardized uptake value (SUVmax), whole-body melanotic tumoral volume (WBMTV), and whole-body total lesion melanin (WBTLM). Receiver operating characteristic (ROC), Kaplan-Meier and Cox regression analyses were performed.

RESULTS

Seventy-six patients (47 men and 29 women; mean age, 57.99 ± 10.72 years) were included for analysis. Median follow-up was 12.0 months (range: 1-22 months). Eighteen patients died and 38 experienced progression. Median OS was 17.60 months (95% confidence interval, 15.89-19.31). In the ROC analysis, [18F]-PFPN PET parameters were superior to those of [18F]-FDG PET in prognosticating death and disease progression. PFS and OS were significantly better in patients with lower SUVmax, WBMTV, and WBTLM on [18F]-PFPN PET (log-rank, P < 0.05). In the univariate analyses, distant metastasis, SUVmax, WBMTV, and WBTLM were significantly associated with cumulative incidence of PFS and OS (P < 0.05). In the multivariate analysis, SUVmax was an independent predictor of PFS and OS.

CONCLUSIONS

[18F]-PFPN PET has a role in prognostication of melanoma patients. Patients with higher [18F]-PFPN SUVmax have worse prognosis.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov, NCT05645484. Registered 9 December, 2022, https://clinicaltrials.gov/ct2/show/NCT05645484?cond=The+Prognostic+Value+of+18F-PFPN+PET+Imaging+in+Patients+With+Malignant+Melanoma&draw=2&rank=1.

Diagnostic performance of 18F-fluorodeoxyglucose positron emission tomography/computed tomography in anorectal melanoma

To evaluate the diagnostic role of ¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography (PET/CT) in initial staging and restaging of anorectal melanoma. This was a single-institution, retrospective observational study; patients for initial staging and with clinical or radiological suspicion of disease recurrence referred for PET/CT between January 2006 and December 2015 were included in the study. Diagnostic performance of PET/CT was evaluated for baseline staging and disease recurrence. A total of 61 patients who were referred for initial staging were included. PET/CT correctly detected primary lesion in 57 (93.44%) cases, regional nodes in 46 (75.4%) cases, nonregional nodes in 22 (36%) cases, and distant metastases in 25 (41%) cases. The sensitivity (SN); specificity (SP); positive predictive value (PPV); negative predictive value (NPV); and accuracy for primary lesion, regional nodes, nonregional nodes, and distant metastases were 96.6%, 100%, 100%, 50%, and 96.7%; 97.9%, 100%, 100%, 93.3%, and 98.4%; 100%, 100%, 100%, 100%, and 100%; and 100%, 100%, 100%, 100%, and 100%, respectively. A total of 24 patients were included for suspected recurrence/restaging. All the patients were treated previously by surgery, radiotherapy, or chemotherapy. PET/CT detected disease recurrence in 20 (83.3%) patients. Ten patients had recurrence at the primary site, 8 of whom also had distant metastases and 2 had only locoregional metastatic nodes. In the remaining 10 patients, there was no primary site recurrence; however, 2 patients had locoregional nodal and distant metastases and 8 patients had only distant metastases. PET/CT was false negative in 1 patient, which missed liver metastasis. SN, SP, PPV, and NPV of PET/CT was found to be 95%, 100%, 100%, and 75%, respectively, with accuracy of 96%. PET/CT demonstrates overall high diagnostic accuracy in the initial staging and detection of recurrent disease in cases of anorectal melanoma.

The impact of particulate electron paramagnetic resonance oxygen sensors on fluorodeoxyglucose imaging characteristics detected via positron emission tomography

During a first-in-humans clinical trial investigating electron paramagnetic resonance tumor oximetry, a patient injected with the particulate oxygen sensor Printex ink was found to have unexpected fluorodeoxyglucose (FDG) uptake in a dermal nodule via positron emission tomography (PET). This nodule co-localized with the Printex ink injection; biopsy of the area, due to concern for malignancy, revealed findings consistent with ink and an associated inflammatory reaction. Investigations were subsequently performed to assess the impact of oxygen sensors on FDG-PET/CT imaging. A retrospective analysis of three clinical tumor oximetry trials involving two oxygen sensors (charcoal particulates and LiNc-BuO microcrystals) in 22 patients was performed to evaluate FDG imaging characteristics. The impact of clinically used oxygen sensors (carbon black, charcoal particulates, LiNc-BuO microcrystals) on FDG-PET/CT imaging after implantation in rat muscle (n = 12) was investigated. The retrospective review revealed no other patients with FDG avidity associated with particulate sensors. The preclinical investigation found no injected oxygen sensor whose mean standard uptake values differed significantly from sham injections. The risk of a false-positive FDG-PET/CT scan due to oxygen sensors appears low. However, in the right clinical context the potential exists that an associated inflammatory reaction may confound interpretation.

Ultrasound, CT, MRI, or PET-CT for staging and re-staging of adults with cutaneous melanoma

BACKGROUND

Melanoma is one of the most aggressive forms of skin cancer, with the potential to metastasise to other parts of the body via the lymphatic system and the bloodstream. Melanoma accounts for a small percentage of skin cancer cases but is responsible for the majority of skin cancer deaths. Various imaging tests can be used with the aim of detecting metastatic spread of disease following a primary diagnosis of melanoma (primary staging) or on clinical suspicion of disease recurrence (re-staging). Accurate staging is crucial to ensuring that patients are directed to the most appropriate and effective treatment at different points on the clinical pathway. Establishing the comparative accuracy of ultrasound, computed tomography (CT), magnetic resonance imaging (MRI), and positron emission tomography (PET)-CT imaging for detection of nodal or distant metastases, or both, is critical to understanding if, how, and where on the pathway these tests might be used.

OBJECTIVES

Primary objectivesWe estimated accuracy separately according to the point in the clinical pathway at which imaging tests were used. Our objectives were:• to determine the diagnostic accuracy of ultrasound or PET-CT for detection of nodal metastases before sentinel lymph node biopsy in adults with confirmed cutaneous invasive melanoma; and• to determine the diagnostic accuracy of ultrasound, CT, MRI, or PET-CT for whole body imaging in adults with cutaneous invasive melanoma:○ for detection of any metastasis in adults with a primary diagnosis of melanoma (i.e. primary staging at presentation); and○ for detection of any metastasis in adults undergoing staging of recurrence of melanoma (i.e. re-staging prompted by findings on routine follow-up).We undertook separate analyses according to whether accuracy data were reported per patient or per lesion.Secondary objectivesWe sought to determine the diagnostic accuracy of ultrasound, CT, MRI, or PET-CT for whole body imaging (detection of any metastasis) in mixed or not clearly described populations of adults with cutaneous invasive melanoma.For study participants undergoing primary staging or re-staging (for possible recurrence), and for mixed or unclear populations, our objectives were:• to determine the diagnostic accuracy of ultrasound, CT, MRI, or PET-CT for detection of nodal metastases;• to determine the diagnostic accuracy of ultrasound, CT, MRI, or PET-CT for detection of distant metastases; and• to determine the diagnostic accuracy of ultrasound, CT, MRI, or PET-CT for detection of distant metastases according to metastatic site.

SEARCH METHODS

We undertook a comprehensive search of the following databases from inception up to August 2016: Cochrane Central Register of Controlled Trials; MEDLINE; Embase; CINAHL; CPCI; Zetoc; Science Citation Index; US National Institutes of Health Ongoing Trials Register; NIHR Clinical Research Network Portfolio Database; and the World Health Organization International Clinical Trials Registry Platform. We studied reference lists as well as published systematic review articles.

SELECTION CRITERIA

We included studies of any design that evaluated ultrasound (with or without the use of fine needle aspiration cytology (FNAC)), CT, MRI, or PET-CT for staging of cutaneous melanoma in adults, compared with a reference standard of histological confirmation or imaging with clinical follow-up of at least three months' duration. We excluded studies reporting multiple applications of the same test in more than 10% of study participants.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted all data using a standardised data extraction and quality assessment form (based on the Quality Assessment of Diagnostic Accuracy Studies 2 (QUADAS-2)). We estimated accuracy using the bivariate hierarchical method to produce summary sensitivities and specificities with 95% confidence and prediction regions. We undertook analysis of studies allowing direct and indirect comparison between tests. We examined heterogeneity between studies by visually inspecting the forest plots of sensitivity and specificity and summary receiver operating characteristic (ROC) plots. Numbers of identified studies were insufficient to allow formal investigation of potential sources of heterogeneity.

MAIN RESULTS

We included a total of 39 publications reporting on 5204 study participants; 34 studies reporting data per patient included 4980 study participants with 1265 cases of metastatic disease, and seven studies reporting data per lesion included 417 study participants with 1846 potentially metastatic lesions, 1061 of which were confirmed metastases. The risk of bias was low or unclear for all domains apart from participant flow. Concerns regarding applicability of the evidence were high or unclear for almost all domains. Participant selection from mixed or not clearly defined populations and poorly described application and interpretation of index tests were particularly problematic.The accuracy of imaging for detection of regional nodal metastases before sentinel lymph node biopsy (SLNB) was evaluated in 18 studies. In 11 studies (2614 participants; 542 cases), the summary sensitivity of ultrasound alone was 35.4% (95% confidence interval (CI) 17.0% to 59.4%) and specificity was 93.9% (95% CI 86.1% to 97.5%). Combining pre-SLNB ultrasound with FNAC revealed summary sensitivity of 18.0% (95% CI 3.58% to 56.5%) and specificity of 99.8% (95% CI 99.1% to 99.9%) (1164 participants; 259 cases). Four studies demonstrated lower sensitivity (10.2%, 95% CI 4.31% to 22.3%) and specificity (96.5%,95% CI 87.1% to 99.1%) for PET-CT before SLNB (170 participants, 49 cases). When these data are translated to a hypothetical cohort of 1000 people eligible for SLNB, 237 of whom have nodal metastases (median prevalence), the combination of ultrasound with FNAC potentially allows 43 people with nodal metastases to be triaged directly to adjuvant therapy rather than having SLNB first, at a cost of two people with false positive results (who are incorrectly managed). Those with a false negative ultrasound will be identified on subsequent SLNB.Limited test accuracy data were available for whole body imaging via PET-CT for primary staging or re-staging for disease recurrence, and none evaluated MRI. Twenty-four studies evaluated whole body imaging. Six of these studies explored primary staging following a confirmed diagnosis of melanoma (492 participants), three evaluated re-staging of disease following some clinical indication of recurrence (589 participants), and 15 included mixed or not clearly described population groups comprising participants at a number of different points on the clinical pathway and at varying stages of disease (1265 participants). Results for whole body imaging could not be translated to a hypothetical cohort of people due to paucity of data.Most of the studies (6/9) of primary disease or re-staging of disease considered PET-CT, two in comparison to CT alone, and three studies examined the use of ultrasound. No eligible evaluations of MRI in these groups were identified. All studies used histological reference standards combined with follow-up, and two included FNAC for some participants. Observed accuracy for detection of any metastases for PET-CT was higher for re-staging of disease (summary sensitivity from two studies: 92.6%, 95% CI 85.3% to 96.4%; specificity: 89.7%, 95% CI 78.8% to 95.3%; 153 participants; 95 cases) compared to primary staging (sensitivities from individual studies ranged from 30% to 47% and specificities from 73% to 88%), and was more sensitive than CT alone in both population groups, but participant numbers were very small.No conclusions can be drawn regarding routine imaging of the brain via MRI or CT.

AUTHORS' CONCLUSIONS

Review authors found a disappointing lack of evidence on the accuracy of imaging in people with a diagnosis of melanoma at different points on the clinical pathway. Studies were small and often reported data according to the number of lesions rather than the number of study participants. Imaging with ultrasound combined with FNAC before SLNB may identify around one-fifth of those with nodal disease, but confidence intervals are wide and further work is needed to establish cost-effectiveness. Much of the evidence for whole body imaging for primary staging or re-staging of disease is focused on PET-CT, and comparative data with CT or MRI are lacking. Future studies should go beyond diagnostic accuracy and consider the effects of different imaging tests on disease management. The increasing availability of adjuvant therapies for people with melanoma at high risk of disease spread at presentation will have a considerable impact on imaging services, yet evidence for the relative diagnostic accuracy of available tests is limited.

18F-FDG PET/CT in the detection of asymptomatic malignant melanoma recurrence

Aim: To evaluate the diagnostic accuracy of FDG PET/CT in the detection of asymptomatic recurrence in patients with malignant melanoma who have had resection of their primary lesion. We also aimed to determine the pattern and factors predisposing to disease recurrence. Methods: Patients with malignant melanoma who have had surgical resection of their disease and without any clinical evidence of disease recurrence were followed- up with FDG PET/CT. The diagnostic accuracy of FDG PET/CT, pattern of recurrence and factors predictive of disease recurrence were determined. Results: A total of 144 patients were followed-up for a median period of 50.50 months. Asymptomatic recurrence was seen in 37 patients (25.7 %) with a median time to recurrence of 20 months. Lymph node was the commonest site of asymptomatic recurrence. Sex, tumour depth, histology type and presence of nodal metastasis were significant predictors of tumour recurrence. Age, race, site of primary lesion, type of lymph node resection were not significant predictors of disease recurrence. Race has a significant effect on the histological subtype of tumour (nodular maligna was more common in Caucasian while acral lentiginous was more prevalent in the Blacks) and the site of the primary lesion (lower limb in Blacks and trunk in Caucasians). Sensitivity, specificity and accuracy of FDG PET/CT for the detection of disease recurrence were 94.5 %, 87.6 % and 89.6 % respectively. Conclusion: FDG PET/CT is a suitable modality for early detection of asymptomatic recurrence of malignant melanoma. Asymptomatic recurrence most commonly occurs in lymph nodes. Sex, nodal metastasis and tumour pathologic features are predictors of recurrence.

Imaging of gastrointestinal melanoma metastases: Correlation with surgery and histopathology of resected specimen

OBJECTIVE

To assess the appearance of gastrointestinal melanoma metastases on CT and PET/CT and evaluate the diagnostic value of CT and PET/CT compared with surgery and histopathology.

METHODS

We retrospectively included 41 consecutive patients (aged 56.1 ± 13.5 years) with gastrointestinal melanoma metastases who underwent preoperative imaging (CT: all, PET/CT: n = 24) and metastasectomy. Two blinded radiologists assessed CT and PET/CT for gastrointestinal metastases and complications. Diagnostic accuracy and differences regarding lesion detectability and complications were assessed, using surgical findings and histopathology as standard of reference.

RESULTS

Fifty-three gastrointestinal melanoma metastases (5.0 ± 3.8 cm) were confirmed by surgery and histopathology. Lesions were located in the small bowel (81.1 %), colon (15.1 %) and stomach (3.8 %), and described as infiltrating (30.2 %), polypoid (28.3 %), cavitary (24.5 %) and exoenteric (17.0 %). Fifteen patients (37 %) had gastrointestinal complications. Higher complication rates were associated with large and polypoid lesions (p ≤ .012). Diagnostic accuracy was high for CT and PET/CT (AUC ≥ .802). For reader B (less experienced), CT yielded lower diagnostic accuracy than PET/CT (p = .044).

CONCLUSION

Most gastrointestinal melanoma metastases were located in the small bowel. Large and polypoid metastases were associated with higher complication rates. PET/CT was superior for detection of gastrointestinal melanoma metastases and should be considered in patients with limited disease undergoing surgery.

KEY POINTS

• Gastrointestinal melanoma metastases (GI-MM) are rare but often cause serious gastrointestinal complications. • Early detection of GI-MM is important to prevent complications and guide surgery. • PET/CT is superior to CT for detection of GI-MMs. • PET/CT should be considered for patients with limited disease before surgical resection.

Detection of Metastases in Patients with Cutaneous Melanoma Using FDG-PET/CT

This study aimed to detect metastases in patients with stage III or IV cutaneous melanoma by 18F-fluorodeoxyglucose positron emission tomography combined with computed tomography (FDG-PET/CT). Thirty-nine patients with clinically evident stage III or IV melanoma underwent whole-body FDG-PET/CT scans for metastatic disease and these results were compared with those of biopsy. Scans for 38 of the patients were evaluated; one patient's scan could not be evaluated. There were 11 true-positive, two false-positive, 24 true-negative and one false-negative scans for the detection of melanoma metastases, with sensitivity 91%, specificity 92%, accuracy 92%, and positive and negative predictive values 84% and 96%, respectively. False-positive FDG-PET/CT scans were due to sarcoidosis in the lung and infected cyst in the liver. It is concluded that FDG-PET/CT scanning has high sensitivity and specificity for detecting stage III or IV metastatic melanoma.

Pulmonary malignant melanoma with distant metastasis assessed by positron emission tomography-computed tomography

Melanoma is a cutaneous malignant neoplasm of melanocytes. Primary malignant melanoma (MM) of the lung is very rare. Although previous reports have described the radiologic features of pulmonary MM, its rarity means that many factors are unknown. Thus, radiologic diagnosis is very difficult. Furthermore, there is little information regarding diagnostic application and/or the usefulness of [¹⁸F]‐fluorine‐2‐fluoro‐2‐deoxy‐D‐glucose positron emission tomography‐computed tomography (FDG‐PET‐CT) for primary pulmonary MM. A 69‐year‐old patient with a productive cough lasting three weeks was admitted to our hospital. Chest CT showed a large single mass with a multi‐lobulated margin and homogeneous enhancement in the right upper lobe, which was subsequently diagnosed as a primary pulmonary MM with multiple metastases. On PET‐CT images, the pulmonary mass and multiple bone lesions showed very increased uptakes of FDG. Considering that pulmonary metastasis from a mucocutaneous melanoma is the main differential diagnosis of primary pulmonary MM, systemic assessment of the whole body is more important than for other types of lung malignancies. This report introduces PET‐CT as a useful diagnostic modality for pulmonary MM, especially in cases of distant multiple metastases.

Synthesis and preclinical characterization of [18F]FPBZA: a novel PET probe for melanoma

INTRODUCTION

Benzamide can specifically bind to melanoma cells. A 18F-labeled benzamide derivative, [18F]N-(2-diethylaminoethyl)-4-[2-(2-(2-fluoroethoxy) ethoxy)ethoxy]benzamide ([18F]FPBZA), was developed as a promising PET probe for primary and metastatic melanoma.

METHODS

[18F]FPBZA was synthesized via a one-step radiofluorination in this study. The specific uptake of [18F]FPBZA was studied in B16F0 melanoma cells, A375 amelanotic melanoma cells, and NB-DNJ-pretreated B16F0 melanoma cells. The biological characterization of [18F]FPBZA was performed on mice bearing B16F0 melanoma, A375 amelanotic melanoma, or inflammation lesion.

RESULTS

[18F]FPBZA can be prepared efficiently with a yield of 40-50%. The uptake of [18F]FPBZA by B16F0 melanoma cells was significantly higher than those by A375 tumor cells and NB-DNJ-pretreated B16F0 melanoma cells. B16F0 melanoma displayed prominent uptake of [18F]FPBZA at 2 h (7.81±0.82%ID/g), compared with A375 tumor and inflammation lesion (3.00±0.71 and 1.67±0.56%ID/g, resp.). [18F]FPBZA microPET scan clearly delineated B16F0 melanoma but not A375 tumor and inflammation lesion. In mice bearing pulmonary metastases, the lung radioactivity reached 4.77±0.36%ID/g at 2 h (versus 1.16±0.23%ID/g in normal mice).

CONCLUSIONS

Our results suggested that [18F]FPBZA PET would provide a promising and specific approach for the detection of primary and metastatic melanoma lesions.

Cost-effectiveness of adding FDG-PET or CT to the diagnostic work-up of patients with stage III melanoma

OBJECTIVE

The aim of this prospective study was to assess predictive value of fludeoxyglucose-positron emission tomography (FDG-PET) and computed tomography (CT) and to analyze their cost-effectiveness in several diagnosis-treatment combinations.

BACKGROUND

The incidence of melanoma continues to rise. A proportion will present or recur with lymph node metastases (American Joint Committee on Cancer/Union for International Cancer Control stage III). To detect distant metastases, CT and/or FDG-PET are available. However, few studies have assessed their value and costs in stage III.

METHODS

All consecutive patients with melanoma with palpable, proven lymph node metastases (2003-2008) referred for examination with FDG-PET and CT were prospectively included. Sensitivity, specificity, and accuracy, and positive predictive value (PPV) and negative predictive value (NPV) were calculated. In economic evaluation, the costs of diagnostic work-up with and without FDG-PET and CT were compared.

RESULTS

Overall, 253 patients with melanoma were included. FDG-PET showed a higher sensitivity than CT: 86.1% compared with 78.2%. Specificity was higher for CT (93.7%) compared with FDG-PET (93.1%). Overall, FDG-PET showed a higher PPV and NPV. Cost-consequence analysis showed that adding CT (True-Positive upstaging in 61 patients) to diagnostic work-up decreased cost by 5.5%, adding FDG-PET (True-Positive upstaging in 68 patients) increased cost by 7.2%, and adding both (True-Positive upstaging in 78 patients) increased cost by 15.1%.

CONCLUSIONS

In this study, FDG-PET had higher sensitivity and predictive value, whereas CT had a higher specificity. Adding one of these diagnostic tools improved the staging of stage III patients with less than 10% cost increase. A proposal for stage-specific use of imaging modalities for clinicians caring for patients with melanoma is presented.

Fluorodeoxyglucose positron emission tomography fails to detect distant metastases at initial staging of melanoma patients with metastatic involvement of sentinel lymph node

BACKGROUND

Positron emission tomography (PET) using fluorodeoxyglucose (FDG) has proven to be more sensitive and accurate than other imaging modalities for the detection of distant metastases in patients with melanoma. Sentinel lymph node (SLN) status is the most important prognostic factor in melanoma patients with no evidence of distant metastasis.

OBJECTIVES

To assess the rate of distant metastases in patients with a positive SLN biopsy (SLNB).

METHODS

Forty-six consecutive patients with a positive SLNB underwent PET or PET-computed tomography within 6 weeks of the SLNB procedure. The patients did not present any clinical sign of nodal involvement or of distant metastasis. PET findings were classified as positive, negative or nonconclusive.

RESULTS

No patient had a positive PET scan for distant metastasis. Six patients (13%) had a nonconclusive PET scan; none of them presented distant metastasis within 12 months. Forty patients (87%) had a negative PET scan; among them five (12%) presented with distant metastasis within 12 months.

CONCLUSIONS

Fluorodeoxyglucose positron emission tomography failed to detect distant metastases at initial staging in patients with a positive SLNB, even in patients who presented with distant metastases within 12 months after the FDG PET scan. These results could be explained by the low prevalence of macroscopic metastatic disease at this stage and by the important delay between the onset of the spread of microscopic metastatic disease and the identification by PET scan of macroscopic metastatic disease.

Melanoma

This chapter discusses the value of FDG-PET and combined FDG-PET/CT in staging and follow-up of melanoma patients. For melanoma patients, the presence or absence of regional lymph node metastases is one of the most important prognostic factors; the recent development of sentinel lymph node biopsy offers a highly sensitive staging method. FDG-PET has shown a limited sensitivity to detect microscopic lymph node metastases in this selected group of patients with stages I and II melanoma. However, for the detection of distant metastases, FDG-PET is frequently used. Although there is no consensus, some surgeons pursue surgical excision of metastatic disease if only one or a few sites of disease are apparent. Precise identification of the location and number of metastatic lesions could therefore be important for surgical planning. Even though patients with metastatic melanoma generally have a poor prognosis (5-year survival 3-16%), there is still a need for accurate staging. Firstly, to identify those patients who may benefit from a surgical procedure, while avoiding these potentially harmful surgical procedures for patients with multiple distant metastases. Secondly, accurate staging is important to improve the efficiency of clinical trials, and thirdly, to provide patients with detailed information about their prognosis. Taking the published literature together, and reasoning that FDG-PET/CT is the current standard in PET imaging, there may be a case for the combined PET/CT in the setting of metastatic melanoma. However, further research is needed as the benefit of the combined FDG-PET/CT vs. FDG-PET alone seems to be less than reported for other tumor entities, which may be due to the high avidity of melanoma for FDG, so that many of the metastases are detected with FDG-PET and the additional CT does not increase the sensitivity.

Contemporary diagnostic imaging modalities for the staging and surveillance of melanoma patients: a meta-analysis

BACKGROUND

Meta-analyses were performed to examine the utility of ultrasonography, computed tomography (CT), positron emission tomography (PET), and a combination of both (PET-CT) for the staging and surveillance of melanoma patients.

METHOD

Patient-level data from 74 studies containing 10,528 patients (between January 1, 1990, and June, 30, 2009) were used to derive characteristics of the diagnostic tests used. Meta-analyses were conducted by use of Bayesian bivariate binomial models to estimate sensitivity and specificity. Diagnostic odds ratios [ie, true-positive results/false-negative results)/(false-positive results/true-negative results)] and their 95% credible intervals (CrIs) and positive predictive values were used as indicators of test performance.

RESULTS

Among the four imaging methods examined for the staging of regional lymph nodes, ultrasonography had the highest sensitivity (60%, 95% CrI = 33% to 83%), specificity (97%, 95% CrI = 88% to 99%), and diagnostic odds ratio (42, 95% CrI = 8.08 to 249.8). For staging of distant metastases, PET-CT had the highest sensitivity (80%, 95% CrI = 53% to 93%), specificity (87%, 95% CrI = 54% to 97%), and diagnostic odds ratio (25, 95% CrI = 3.58 to 198.7). Similar trends were observed for melanoma surveillance of lymph node involvement, with ultrasonography having the highest sensitivity (96%, 95% CrI = 85% to 99%), specificity (99%, 95% CrI = 95% to 100%), and diagnostic odds ratio (1675, 95% CrI = 226.6 to 15,920). For distant metastases, PET-CT had the highest sensitivity (86%, 95% CrI = 76% to 93%), specificity (91%, 95% CrI = 79% to 97%), and diagnostic odds ratio (67, 95% CrI = 20.42 to 229.7). Positive predictive values were likewise highest for ultrasonography in lymph node staging and for PET-CT in detecting distant metastases.

CONCLUSION

Among the compared modalities, ultrasonography was superior for detecting lymph node metastases, and PET-CT was superior for the detection of distant metastases in both the staging and surveillance of melanoma patients.

Meta-analysis of the performance of (18)F-FDG PET in cutaneous melanoma

INTRODUCTION

The aim of this study was to perform a systematic review of the literature to evaluate the accuracy of FDG-PET in staging and restaging of cutaneous melanoma.

METHODS

Systematic methods were used to identify, select, and evaluate the methodologic quality of the studies as well as to summarize the overall findings of sensitivity and specificity. The search strategy consisted of identifying studies published between 2000 and 2006. Inclusion criteria were studies that evaluated the diagnostic performance of FDG-PET in staging/restaging of cutaneous melanoma. The results were compared and pooled with a meta-analysis published previously that included studies published until 1999. The meta-analysis included 95% confidence intervals (CI) of sensitivity, specificity, likelihood-ratio (LR), and diagnostic-odds-ratio (DOR).

RESULTS

The quantitative meta-analysis included 24 studies that were analysed in two groups: eight studies were included only in the regional staging analysis (group I), 13 studies were included only in the detection of distant metastases analysis (group II), and three studies were included in both analyses. Compliance with the methodologic-quality criteria was acceptable. We analysed the results of data presented in patients, lesions, basins, lymph-nodes, areas, and scans. Regarding the performance of FDG-PET in the detection of metastases, the pooled studies presented homogeneity for the negative-LR (0.15; 95% CI, 0.10-0.22) when analyzing lesions. When analyzing scans, there was global homogeneity for specificity (0.86; 95% CI, 0.77-0.92), positive-LR (5.86; 95% CI, 3.64-9.43), and DOR (37.89; 95% CI, 15.80-90.86). The pooled studies presented heterogeneity for the other items analysed. Regarding the detection of regional metastases, when analyzing lymph-nodes there was global homogeneity for specificity (0.99; 95% CI, 0.97-0.99; P = 0.101). The meta-regression evidenced that the variable that most influenced the DOR of the different studies and that can explain the heterogeneity was the year of publication; this may be related to the evolution of PET technology and an improvement of sensitivity/specificity.

CONCLUSION

FDG-PET is not useful in the evaluation of regional metastases, as it does not detect microscopic disease. However, FDG-PET could be useful in the detection of distant metastases, and could suggest its utility in the management of patients with cutaneous melanoma.

Positron emission tomography/computed tomography: the current technology and applications

Positron emission tomography (PET) and combined PET/CT provide powerful metabolic and anatomical information together in a single exam. This article reviews the fundamentals of PET physics, the state of the art and future directions in PET technology, and the current clinical applications of PET. The latter is quite diverse and includes oncology, cardiology, neurology, and infection and inflammation imaging, all with FDG as the tracer. Additionally, novel radiopharmeuticals are under development, many of which are target cellular processes that are more specific than glucose metabolism.

Imaging in cutaneous melanoma

Cutaneous melanoma (CM) is a common malignancy and imaging, particularly lymphoscintigraphy (LS), positron-emission tomography with 2-fluoro-2-deoxyglucose (FDG-PET), ultrasound, radiography computed tomography (CT) and magnetic resonance imaging have important roles in staging and restaging, surgical guidance, surveillance and assessment of recurrent disease. This review aims to summarize the available data regarding these and other imaging modalities in CM and provide the basis for subsequent formulation of guidelines regarding the use of imaging in CM. PubMed and Medline searches were performed and reference lists from publications were also searched. The published data were reviewed and tabulated. There is level I evidence supporting the use of LS and sentinel lymph node biopsy in nodal staging for CM. There is level III evidence demonstrating the superiority of ultrasound to palpation in the assessment of lymph nodes in CM. There is level IV evidence supporting FDG-PET in American Joint Committee on Cancer stage III/IV and recurrent CM and that FDG-PET/CT may be superior to FDG-PET. Level IV evidence also supports the use of CT in the same group of patients and the role of CT appears to be complementary to FDG-PET. Various imaging modalities, especially LS/sentinel lymph node biopsy and FDG-PET/CT, add incremental information in the management of CM and the various modalities have complementary roles depending on the clinical situation.

Treatment of melanoma and nonmelanoma skin cancer

The incidence of skin cancer is increasing in Caucasian populations worldwide. Treatment approaches for Nonmelanoma skin cancer (NMSC) are predominantly curative and surgery can be regarded as standard of care. Nevertheless, novel and less invasive topical therapy modalities like photodynamic therapy or local immune modifiers are in progress. In contrast to NMSC, the mortality of melanoma has not changed considerably over the last years and decades. Melanoma survival mainly depends on primary tumor thickness underlining the importance of primary and secondary prevention by avoidance or early detection of the disease. The chance to cure melanoma patients is steadily decreasing with tumor stage. As the prognosis in distant metastatic disease is still poor, except for single situations therapy approaches are palliative and accompanied by an optimal supportive care of the patients concerned. Albeit removal of localized metastases is currently the most effective approach in metastatic melanoma, chemo- and chemoimmunotherapy has to be regarded as standard treatment in most of the cases. Novel and promising therapeutic options accrue from growing insights in tumor biology and immunology. Not only in melanoma, development and application of targeted therapies currently attract the most attention in the treatment of advanced tumors. First clinical experiences with those antiproliferative, antiangiogenic and proapoptotic agents reveal only moderate antitumoral activity in melanoma, so that future efforts aim at defining more effective combination strategies using chemo-, targeted and vaccination therapy approaches.

Assessing response to chemotherapy in metastatic melanoma with FDG PET: Early experience

OBJECTIVE

The management of metastatic melanoma remains challenging with only modest response rates to chemotherapy but the need to identify the best re-staging techniques remains paramount. This study evaluates our early experience in the use of FDG PET-CT in the assessment of early response to chemotherapy in metastatic melanoma.

METHODS

FDG PET-CT was performed at baseline and following two or three cycles of combination or single agent chemotherapy in seven patients. Response was assessed visually as complete, partial metabolic response or progressive disease.

RESULTS

There was intense FDG uptake in all metastases at baseline. Following two to three cycles of chemotherapy, there was a complete metabolic response (CMR) in one patient, partial metabolic response (PMR) in two patients and progressive metabolic disease (PMD) in the remaining three patients. Survival was 679 days in the single patient with a CMR, median of 206 and 129 days in the patients with PMR and PMD respectively.

CONCLUSION

This pilot study demonstrates the potential use of FDG PET as a biomarker in early response assessment to chemotherapy in metastatic melanoma. PET-CT already plays in integral role in staging high risk melanoma patients and it may also have a promising role in assessing response to current and novel therapies. Further larger studies examining specific therapies and optimal timing are required.

PET/CT in oncology: for which tumours is it the reference standard?

Positron emission tomography (PET)/computed tomography (CT) has a growing role in the imaging of many cancers. As our experience has grown over the past number of years so has our understanding for which cancers it is particularly useful. The value of PET/CT at each stage of the cancer journey is different for each cancer. This review attempts to tease out the role of PET/CT in the common cancers with particular emphasis on where it is the imaging investigation of choice.

Selected patients with metastatic melanoma may benefit from liver resection

BACKGROUND

In the last few years there has been expanding use of hepatic resection for non-colorectal metastases. The purpose of this study is to evaluate the experience of liver resection for patients with metastatic melanoma.

METHODS

Eighteen patients with metastatic melanoma were explored for possible surgical resection. All patients fitted the following criteria: absence of extra-hepatic disease after evaluation with CT/MRI and FDG-PET scans; disease-free interval longer than 24 months after the resection of the primary melanoma; presumed completely resectable lesions; absence of clinical co-morbidities.

RESULTS

Liver resection was performed in 10 patients; 8 out of 18 presented with irresectable tumors and/or peritoneal metastases and were not operated. One patient presented with postoperative biliary fistula and was conservatively managed. No other complications or postoperative mortality were observed. After a mean follow-up of 25.4 months, 5 patients are alive and without evidence of recurrence. Overall median survival was 22 months; overall survival and disease-free survival were 70% and 50% respectively.

CONCLUSIONS

Resection of liver metastases from melanoma in a selected group of patients may increase survival. Exploratory laparoscopy should be included in the preoperative armamentarium of diagnostic tools.

PET/CT: form and function

Functional imaging with positron emission tomography (PET) is playing an increasingly important role in the diagnosis and staging of malignant disease, image-guided therapy planning, and treatment monitoring. PET with the labeled glucose analogue fluorine 18 fluorodeoxyglucose (FDG) is a relatively recent addition to the medical technology for imaging of cancer, and FDG PET complements the more conventional anatomic imaging modalities of computed tomography (CT) and magnetic resonance imaging. CT is complementary in the sense that it provides accurate localization of organs and lesions, while PET maps both normal and abnormal tissue function. When combined, the two modalities can help both identify and localize functional abnormalities. Attempts to align CT and PET data sets with fusion software are generally successful in the brain; other areas of the body is more challenging, owing to the increased number of degrees of freedom between the two data sets. These challenges have recently been addressed by the introduction of the combined PET/CT scanner, a hardware-oriented approach to image fusion. With such a device, accurately registered anatomic and functional images can be acquired for each patient in a single scanning session. Currently, over 800 combined PET/CT scanners are installed in medical institutions worldwide, many of them for the diagnosis and staging of malignant disease and increasingly for monitoring of the response to therapy. This review will describe some of the most recent technologic developments in PET/CT instrumentation and the clinical indications for which combined PET/CT has been shown to be more useful than PET and CT performed separately.

Non-invasive imaging of tissue PO2 in malignant melanoma of the skin

In various tumor systems, decreased PO2 values have been demonstrated by various methods. This study addresses the question of whether tumor hypoxia can be found in cutaneous melanoma using lifetime imaging of non-invasive sensors showing phosphorescence quenched by oxygen. Twenty-three cases of cutaneous malignant melanoma (average tumor thickness 1.25 mm, range 0.5-8 mm) were examined using the SkinCam lifetime imaging system for the assessment of cutaneous PO2 levels within the tumors and in adjacent clinically normal skin. For comparison, 30 non-melanoma skin tumors were evaluated. In 15 exploitable melanoma cases, the average hypoxic difference of the lesion compared with the surrounding skin was -10 mmHg, typically associated with an inhomogeneous distribution. Only 10% of the non-melanoma lesions showed a similar hypoxia (false positives). The SkinCam equipment uses a non-invasive imaging method and provides further diagnostic hints in the assessment of benign and malignant skin tumors.

Therapie des metastasierten Melanoms

The incidence of malignant melanoma is steadily increasing worldwide. The most crucial requirement to cure the disease is early detection of thin primary tumors. At the stage of distant metastases, the treatment options are predominantly palliative. Resection of localized metastases is currently the most effective approach. Dacarbazine is considered as standard chemotherapy for inoperable metastatic disease showing remission rates of 5-20% without any noteworthy effect on overall survival. Quite recently, a large spectrum of innovative treatment approaches have been developed from an increasing insight into tumor biology. Along with improved vaccination strategies, targeted therapies have attracted the most attention in the treatment of advanced melanoma. Those anti-proliferative, anti-angiogenic and proapoptotic agents are directed against pathogenetically important pathways of the tumor cell. First clinical experiences are encouraging, but results from controlled trials have to be awaited.

Positron Emission Tomography: A Promising Diagnostic Modality for Head and Neck Pathology

PURPOSE

The purpose of this study is to discuss the advantages of positron emission tomography (PET) imaging in the diagnosis of head and neck lesions.

METHODS

To illustrate this diagnostic method, we describe the nuclear medicine basic technique, present 5 cases for comparison of the results between computed tomography (CT) scan and PET, and review the literature.

RESULTS

The 5 cases show that PET allows assessment of lesions earlier and more definitively than other diagnostic images.

CONCLUSIONS

PET, a nuclear medicine modality, is a promising tool for diagnosis and follow-up of head and neck lesions. PET allows assessment of changes in the tissue before they would be shown by other diagnostic images. This modality permits differentiation between malignant and benign tumors. It also has the capability to distinguish between scar tissue, necrosis, tumor recurrence, and metastatic disease. It allows the assessment of the patient's progress during therapy, making possible an early identification of nonresponders to therapy.

Novel Imaging Techniques in Melanoma

Cutaneous melanoma is one of the most deadly malignancies. Although it accounts for approximately 4% of all cancer cases, it ac-counts for approximately 79% of skin cancer-related deaths. In the past few years, the nuclear medicine platform used in the management of melanoma has extended to biochemical and structural imaging. In clinical practice, integrated positron emission tomography/CT devices allow anatomic and metabolic characterization of meta-static disease in a single study. Similarly, more accurate localization of sentinel nodes in a 3-D space now is feasible with hybrid single photon emission CT/CT system. In translational research, [18F]fluorodeoxyglucose probes have been designed to optimize the detection of melanoma tumor sites in vivo.

Diagnostic Performance of Whole Body Dual Modality 18F-FDG PET/CT Imaging for N- and M-Staging of Malignant Melanoma: Experience With 250 Consecutive Patients

Purpose

To assess the diagnostic performance of positron emission tomography/computed tomography (PET/CT) using 18F-fluorodeoxyglucose (FDG) for N- and M-staging of cutaneous melanoma.

Patients and Methods

This is a retrospective and blinded study of 250 consecutive patients (105 women, 145 men; age 58 ± 16 years) who underwent FDG-PET/CT for staging of cutaneous melanoma at different time points in the course of disease. Whole-body FDG-PET/CT was performed 101 ± 21 minutes postinjection of 371 ± 41 MBq FDG. Diagnostic accuracy for N- and M-staging was determined for CT alone, PET alone, and PET/CT.

Results

PET/CT detected significantly more visceral and nonvisceral metastases than PET alone and CT alone (98.7%, 88.8%, and 69.7%, respectively). PET/CT imaging thus provided significantly more accurate interpretations regarding overall N- and M-staging than PET alone and CT alone. Overall N- and M-stage was correctly determined by PET/CT in 243 of 250 patients (97.2%; 95% CI, 95.2% to 99.4%) compared with 232 patients (92.8%; 95% CI, 89.6% to 96.0%) by PET, and 197 patients (78.8%; 95% CI, 73.7% to 83.9%) by CT. All differences were significant. Accuracy of PET/CT was significantly higher than that of PET and CT for M-staging (0.98 v 0.93 and 0.84) and significantly higher than that of CT for N-Staging (0.98 v 0.86). Change of treatment according to PET/CT findings occurred in 121 patients (48.4%).

Conclusion

The diagnostic performance of FDG-PET/CT for N- and M-staging of melanoma patients suggests its use for whole-body tumor staging, especially for detection or exclusion of distant metastases.

Utility of Preoperative [(18)]F Fluorodeoxyglucose–Positron Emission Tomography Scanning in High-Risk Melanoma Patients

BACKGROUND

[(18)]F Fluorodeoxyglucose-positron emission tomography (PET) scanning provides functional imaging based on glucose uptake by tumors. Melanoma is a glucose-avid malignancy, and preoperative PET scanning in melanoma patients has the potential to guide appropriate treatment.

METHODS

We performed a prospective trial to evaluate the clinical utility of whole-body fluorine 18-labeled deoxyglucose-PET scanning used in addition to standard imaging (contrast-enhanced computed tomographic [CT] imaging of the chest, abdomen, and pelvis) in preoperative stage IIC (T4N0M0), III (any T, N1 to N3, M0), and IV (any T, any N, M1) melanoma patients. Pathologic or clinical follow-up within 4 to 6 months of the imaging studies was used to determine the accuracy of preoperative PET and CT scan findings.

RESULTS

Preoperative imaging findings led to a change in clinical management in 36 (35%) of 103 patients. In 32 (89%) of these patients, the information was accurate. Findings on PET scan alone (14 of 36; 39%) or in combination with CT (20 of 36; 56%) resulted in a treatment change in most patients (34 of 36; 94%). The most common decision was to cancel the operation (19 of 36; 53%). PET scanning was more sensitive than CT scanning in detecting occult disease (68% vs. 48%; P=.05), but both tests were highly specific (92% vs. 95%; P=.7, PET vs. CT).

CONCLUSIONS

PET scanning facilitates the appropriate management of high-risk melanoma patients being considered for operative intervention. PET imaging in addition to CT scanning should be strongly considered before operation in patients at high risk for occult metastatic disease.

Somatostatin receptor scintigraphy with 111In-DOTA-lanreotide and 111In-DOTA-Tyr3-octreotide in patients with stage IV melanoma: in-vitro and in-vivo results

The overexpression of somatostatin receptors (SST-Rs) on various tumour cells provides the molecular basis for the successful use of radiolabelled SST analogues in clinical oncology. The objective of the study was to evaluate the tumour binding of In-1,4,7,10-tetraazacyclo-dodecane-N,N',N'',N'''-tetraacetic acid-lanreotide (In-DOTA-LAN) and In-DOTA-tyrosine-octreotide (In-DOTA-Tyr-OCT) in patients with stage IV melanoma. In addition, we evaluated the potential antiproliferative effect of SST analogues, together with an assessment of the functionality of SST-Rs, on four melanoma cell lines. Twenty-three patients with advanced metastatic melanoma underwent scintigraphy. Thirty-eight of 61 lesions (62%) were positively imaged with In-DOTA-LAN, whereas 23 (37%) were negative. With In-DOTA-Tyr-OCT, 10 of the 23 documented lesions (43%) were positive and 13 (56%) were negative. In vitro, cell lines showed no growth inhibition in the presence of SST analogues and no influence on cell cycle distribution was found with the addition of SST analogues to cultured cells. In addition, no functional surface SST-Rs could be demonstrated on these cell lines. Taken together, our results demonstrate the visualization of metastatic melanoma in a high percentage of patients, probably due to binding of SST analogues to SST-Rs on tumour vessels or infiltrating immune cells. Judging from our data, however, there is no evidence of functional SST-R expression on melanoma cells.

The clinical role of CT/PET in oncology: an update

FDG-PET imaging has significantly altered the workup of the oncologic patient. With the introduction of combined FDG-PET/CT scanners, there has been a dramatic improvement in lesion detection, lesion characterization and accurate lesion localization. As attenuation correction can be attained with the CT images, PET exam times have been dramatically reduced, by as much as 50% in many instances. In this overview we briefly outline the advantages of CT/PET in oncology especially in diagnosis and clinical management of the common tumor types for which it is mainly used.

Impact of haemoglobin levels during adjuvant chemotherapy on the survival of patients with primary breast cancer

Tumour anaemia is a common symptom in cancer patients, particularly in those receiving chemotherapy. The aim of the current study was to analyse the impact of haemoglobin levels on the prognosis of patients with primary breast cancer receiving adjuvant chemotherapy. A total of 129 patients were available for analysis. The estimated median five-year overall survival rate was 76.6%. Mean Hb prior to primary surgery was 13.8 g/dl (SD 1.09), pre-chemotherapy Hb 12.8 g/dl (SD 1.2), and nadir Hb during chemotherapy 11.0 g/dl (SD1.1), respectively. Hb values were analysed as continuous variables in the Cox model. Survival analyses did not show a correlation between preoperative and pre-chemotherapy Hb levels with patient outcome. However, univariate analysis identified low nadir Hb (p=0.008), larger tumours (p=0.042), and hormone-receptor-negative tumours (p=0.022) to be significantly associated with poor patient survival. This result was persistent when analysis was adjusted for relevant prognostic factors in a multivariate Cox proportional hazards model. Nadir Hb, 1.54-fold increased risk for death (95% CI 1.03-2.32), and tumour size, 3.2-fold increased risk (95% CI 1.17-8.77) remained as independent variables, whereas hormone-receptor status failed to retain significance. The present data showed anaemia during adjuvant chemotherapy to be associated with poor survival in patients with primary breast cancer. Prospective randomized trials are warranted to examine the value of correcting anaemia with regard to improve disease control and survival.

Impact of 2-Deoxy-2[F-18]Fluoro-d-Glucose Positron Emission Tomography on the Management of Patients with Advanced Melanoma

OBJECTIVES

Accurate staging of patients with melanoma is vital to guide appropriate treatment. 2-Deoxy-2-[F-18]fluoro-D-glucose (FDG)-positron emission tomography (PET) has been reported to be a sensitive and specific technique for the staging of advanced melanoma, however, few studies provide information regarding its impact on patient management.

METHODS

We retrospectively reviewed the FDG-PET scan results of 92 patients with melanoma who had 126 scans performed over a six-year period. These patients were seen at the specialist melanoma clinic at our Institution, and 84 patients (92%) had stage III or IV disease. FDG-PET scan results were correlated with computed tomography (CT) scans and other imaging when available, and with clinical follow-up of a minimum of three to six months. The impact of FDG-PET scans on patient management was also assessed.

RESULTS

On a lesion-by-lesion analysis, FDG-PET had a sensitivity of 92%, a specificity of 88%, and an accuracy of 91%. FDG-PET correctly affected the clinical decision-making process in 40 of 126 patient studies (32%), particularly assisting in the selection of patients for surgery.

CONCLUSION

FDG-PET has an important role in guiding the management of patients with advanced melanoma, particularly when surgery is contemplated.

Clinical applications of fluorodeoxyglucose-positron emission tomography in the management of malignant melanoma

PURPOSE OF REVIEW

Malignant melanoma is the seventh most common newly diagnosed cancer among Americans. In most cases, melanoma is curable by means of surgical excision if diagnosed in early stages of the disease. The prognosis is linked directly to the initial stage at the time of diagnosis. Early diagnosis and accurate disease staging is important for appropriate treatment planning. This review focuses on clinical applications of positron emission tomography (PET) using F-fluorodeoxyglucose (FDG) in the management of patients with malignant melanoma.

RECENT FINDINGS

Many investigators have studied the role of FDG-PET in the management of malignant melanoma. PET has been shown to have a strong role in detection of metastatic disease. FDG-PET can highlight metastases at unusual sites that are easily missed with conventional imaging modalities. It is more sensitive than computed tomography (CT) for detection of metastatic lesions in skin, lymph nodes, and abdomen. Despite the overall superiority of FDG-PET in the detection of melanoma metastases, it has limitations in detection of early-stage disease (stage I-II), small lung nodules, and brain metastases. Most of the false-negative FDG-PET results are due to micrometastases and lesions small than 10 mm. False-positive FDG-PET results are due to postsurgical inflammation, other inflammatory lesions, and some benign tumors.

SUMMARY

FDG-PET is a metabolic, noninvasive imaging modality for detecting distant metastatic and recurrent melanoma. FDG-PET is of limited use in patients with early-stage disease and cannot replace sentinel node biopsy, which is much more sensitive in detecting microscopic lymph node metastases.

[The value of 18F-fluoro-2-deoxy-D-glucose positron emission tomography (18F-FDG PET) in diagnosis of neoplastic diseases]

Positron emission tomography (PET) has the ability to detect cancer based on molecular and biochemical processes within the tumor tissues. The most widely used radiotracer in oncology at this time is the glucose analogue 18F-fluoro-2-deoxy-D-glucose (18F-FDG). Like glucose, 18F-FDG is transported into cells by a glucose transporter protein and rapidly converted into 18F-FDG-6-phosphate. PET imaging with 18F-FDG is able to diagnose, stage, and restage many cancers with accuracies ranging from 80% to 90%. Responses to therapy can be identified earlier and with greater accuracy than is possible with anatomic imaging modalities. The prognostic information available through 18F-FDG PET is superior to that of conventional imaging for many cancers. The aim of this review article is to show the most promising clinical indications for the use of PET in oncology.

Fluorodeoxyglucose-PET in the management of malignant melanoma

FDG-PET is of limited use in patients with early-stage disease without nodal or distant metastases (stage I-II), because sentinel node biopsy is much more sensitive in detecting microscopic lymph node metastases. Because of the high tumor-to-background ratio, FDG-PET can highlight metastases at unusual sites that are easily missed with conventional imaging modalities. PET has been shown to have a strong role in detecting metastatic disease. FDG-PET is more sensitive than CT for detecting metastatic lesions in skin, lymph nodes, and abdomen, but CT is equivalent to or more sensitive than FDG-PET for detecting small pulmonary lesions. FDG-PET identifies the location and number of metastatic lesions in stage III and IV disease and therefore is important for surgical planning. Most of the false-negative FDG-PET results are caused by micrometastases and lesion smaller than 10 mm. Postsurgical inflammation, other inflammatory lesions, and some benign tumors cause some false-positive FDG-PET results.

Clinical use of positron emission tomography in the management of cutaneous melanoma

Cutaneous melanoma is the seventh most common newly diagnosed cancer among Americans. It frequently metastasizes and is difficult to treat. Accurate disease staging is important for optimizing therapy and selecting appropriate patients for experimental trials. Positron emission computed tomography (PET) using 18F-fluorodeoxyglucose (FDG) has been studied extensively since 1991 and shows great promise in the detection of metastatic cutaneous melanoma. Cumulative data from the last 13 years is reviewed in this article and suggest that FDG-PET is the modality of choice for evaluating patients who fit into one of four categories: 1) individuals with a high risk for distant metastases based on extent of locoregional disease, 2) patients with findings that are suspicious for distant metastases, 3) individuals with known distant tumor deposits who still stand to benefit from customized therapies if new lesions are discovered or treated lesions regress, and 4) patients at high risk for systemic relapse who are considering aggressive medical therapy. Despite the overall superiority of FDG-PET in the detection of melanoma metastases, limitations exist with respect to detection of small lung nodules and brain metastases, which are better evaluated by computed tomography and magnetic resonance imaging, respectively.

Role of surgery in patients with stage IV melanoma

PURPOSE OF REVIEW

The purpose of this brief review is to highlight recent advances in the surgical treatment of metastatic melanoma; to review factors important in the decision-making process of selecting the most appropriate patients for resection; and to discuss the current literature in the context of site of recurrence.

RECENT FINDINGS

While there are relatively few new findings on the surgical treatment of metastatic melanoma, recent reports do support prior observations in the field. The recently revised staging system for melanoma groups metastatic disease according to prognostic features. There is currently a great deal of interest in the use of 18-fluorodeoxyglucose positron emission tomography (FDG-PET) to more accurately evaluate metastatic disease. The use stereotactic radiosurgery for brain metastases has expanded recently and adds to local treatment options. When procedures are performed with palliative intent, treatment goals must be clearly defined and communicated among the patient, family and surgeon. Improved understanding of the goals of palliative surgery may be facilitated by the concept of a palliative triangle, which helps define the decision making process among the patient, family members, and surgeon.

SUMMARY

Metastatic melanoma is usually associated with a dismal prognosis. When a procedure is performed with palliative intent, appropriately selected patients usually experience reliable relief of symptoms and improved quality of life. Improved survival after a complete resection with curative intent is often predicted by good performance status, longer disease-free interval, limited extent of metastatic disease, and less aggressive tumor biology.

A new animal model for the imaging of melanoma: correlation of FDG PET with clinical outcome, macroscopic aspect and histological classification in Melanoblastoma-bearing Libechov Minipigs

The aim of this study was to evaluate the Melanoblastoma-bearing Libechov Minipigs (MeLiM) as an animal model of melanoma for in vivo imaging. Serial whole-body 2-deoxy-2-[(18)F]fluoro- d-glucose positron emission tomography (FDG PET) scans were conducted on five MeLiM. In order to explore different clinical stages of the tumoural lesions, each animal was scanned two to four times, at intervals of 30-155 days. PET images were analysed by a semiquantitative method based on the tumour to muscle metabolic ratio. Histology was performed on biopsies taken between or after the scans and the histological grading of the tumours was compared with the FDG uptake. The overall sensitivity of FDG PET for the detection of cutaneous melanoma was 75%; 62.5% of involved lymph nodes were positive. Sensitivity was better for tumours with vertical growth than for flat lesions. FDG PET did not detect tumours with epidermal involvement only, nor did it detect small metastatic foci. The metabolic ratio was correlated with the evolution of the melanoma. FDG PET is effective in the staging of cutaneous melanoma and the follow-up of tumoural extension and regression in Melanoblastoma-bearing Libechov Minipigs. The results obtained in this animal model correlate well with those described in human melanoma. Accordingly, this model may be useful in testing new tracers specific for melanoma and in helping to detect molecules expressed early during tumoural regression.