Surveillance imaging with FDG-PET/CT in the post-operative follow-up of stage 3 melanoma

Real-world management of patients with complete response under immune-checkpoint inhibition for advanced melanoma

BACKGROUND

Up to now, the optimal duration of immune checkpoint inhibitors (ICI) has not been evaluated in prospective studies. However, current clinical practice requires decisions to be made regarding the duration of ICI in complete responders.

MATERIAL AND METHODS

A survey was sent to 80 DeCOG skin cancer centers to assess how decisions are made on treatment duration of ICI in melanoma after having reached complete response, and staging intervals after ICI discontinuation. All responses received by March 10, 2024 (51 centers) were included.

RESULTS

The duration of ICI after having achieved complete remission varies between centers from three to 36 months. In total, 66% of the DeCOG centers continue treatment for up to 6 months, after having achieved complete remission (CR) with ICI. In the first year after discontinuation of ICI, most centers perform staging intervals (CT/MRI) every 3 months. More than 60% of centers continue staging at least once per year even in the 4th and 5th year after discontinuation.

CONCLUSIONS

There are significant differences between the centers regarding staging intervals and duration of ICI upon CR. Prospective studies are necessary to determine the optimal time point of ICI discontinuation and follow-up.

False Positive Rate from Prospective Studies of PET-CT in Cutaneous Malignant Melanoma: A Systematic Review and Meta-Analysis

BACKGROUND

Cutaneous malignant melanoma (CMM) is increasing in prevalence and possesses the highest mortality rate of any skin cancer. Positron Emission Tomography and Computed Tomography (PET-CT) may be utilised in either radiological staging or surveillance, primarily in stage III-IV disease. False positive (FP) results lead to patient distress, increased costs, and unnecessary follow-up. The FP rate in CMM literature varies widely, altering calculations of positive predictive value and has not undergone pooled meta-analytic.

MATERIALS AND METHODS

A systematic review and meta-analysis of FP results in prospective studies of PET-CT in CMM was performed in accordance with PRISMA guidelines.

RESULTS

The systematic review produced 14 trials for inclusion. Patient-based reporting had the lowest pooled proportion of FP results with 5.8 % (95 % CI = 3.3 % to 8.8 %), lesion-based was highest with 9.1 % (95 % CI = 3.4 % to 17.2 %) and combined was 6.1 % (95 % CI = 4.3 % to 8.1 %). Bias was low to unclear other than for FP reporting. Heterogeneity (I2) was variable across all analyses. FP findings were mainly lymphatic, dermatological, respiratory, or skeletal. Diagnostic information was not provided.

CONCLUSIONS

This study was the first attempt to quantify the pooled proportion of FP results from PET-CT in CMM. A small number of studies (n = 14) were available due to the predominance of retrospective methodology. Due to inconsistent reporting the true proportion of FP results is unclear. Systemic distribution was expected but limited diagnostic information was provided. Repeat meta-analysis using retrospective work should be performed. Future work should be prospective with clearly documented FP proportion, distribution, diagnosis, and follow-up.

Optimizing time prediction and error classification in early melanoma detection using a hybrid RCNN-LSTM model

Skin cancer is a terrifying disorder that affects all individuals. Due to the significant increase in the rate of melanoma skin cancer, early detection of skin cancer is now more critical than ever before. Malignant melanoma is one of the most serious forms of skin cancer, and it is caused by abnormal melanocyte cell growth. In recent years, skin cancer predictive categorization has become more accurate and predictive due to multiple deep learning algorithms. Malignant melanoma is diagnosed using the Recurrent Convolution Neural Network-Long Short-Term Memory (RCNN-LSTM), which is one of the deep learning classification approaches. Using the International Skin Image Collection and the RCNN-LSTM, the data are categorized and analyzed to gain a better understanding of skin cancer. The method begins with data preprocessing, which prepares the dataset for classification. Additionally, the RCNN is employed to extract the features that are vital to the prediction process. The LSTM is accountable for the final step, classification. There are further factors to examine, such as the precision of 94.60%, the sensitivity of 95.67%, and the F1-score of 95.13%. Other benefits of the suggested study include shorter prediction durations of 95.314, 122.530, and 131.205 s and lower model loss of 0.25%, 0.19%, and 0.15% for input sizes 10, 15, and 20, respectively. Three datasets had a reduced categorization error of 5.11% and an accuracy of 95.42%. In comparison to previous approaches, the work discussed here produces superior outcomes. RESEARCH HIGHLIGHTS: Recurrent convolutional neural network (RCNN) deep learning approach for optimizing time prediction and error classification in early melanoma detection. It extracts a high number of specific features from the skin disease image, making the classification process easier and more accurate. To reduce classification errors in accurately detecting melanoma, context dependency is considered in this work. By accounting for context dependency, the deprivation state is avoided, preventing performance degradation in the model. To minimize melanoma detection model loss, a skin disease image augmentation or regularization process is performed in this work. This strategy improves the accuracy of the model when applied to fresh, previously unobserved data.

Clinical and Imaging Follow-Up for High-Risk Cutaneous Melanoma: Current Evidence and Guidelines

The most recent (eighth) edition of the American Joint Committee on Cancer (AJCC) staging system divides invasive cutaneous melanoma into two broad groups: "low-risk" (stage IA-IIA) and "high-risk" (stage IIB-IV). While surveillance imaging for high-risk melanoma patients makes intuitive sense, supporting data are limited in that they are mostly respective and used varying methods, schedules, and endpoints. As a result, there is a lack of uniformity across different dermatologic and oncologic organizations regarding recommendations for follow-up, especially regarding imaging. That said, the bulk of retrospective and prospective data support imaging follow-up for high-risk patients. Currently, it seems that either positron emission tomography (PET) or whole-body computerized tomography (CT) are reasonable options for follow-up, with brain magnetic resonance imaging (MRI) preferred for the detection of brain metastases in patients who can undergo it. The current era of effective systemic therapies (ESTs), which can improve disease-free survival (DFS) and overall survival (OS) beyond lead-time bias, has emphasized the role of imaging in detecting various patterns of EST response and treatment relapse, as well as the importance of radiologic tumor burden.

Stage IIA Cutaneous Melanoma: Do Regional Ultrasound and CT scan Improve Detection of Relapses? A Multicenter Retrospective Observational Study

INTRODUCTION

Stage IIA cutaneous melanoma is typified by a Breslow thickness between 1.1 and 2.0 mm with ulceration or between 2.1 and 4.0 mm without ulceration. The role of radiological investigations in staging and follow-up of this intermediate-risk subgroup of patients is still debated.

OBJECTIVES

The aim of this study is to investigate the role of imaging procedures in the follow-up of stage IIA melanoma asymptomatic patients.

METHODS

Data were retrieved from two tertiary referral centers in Italy. Among patients with stage IIA melanoma, those who relapsed were investigated concerning type of detection (by patient or by doctor), and modality of detection (clinical examination, ultrasound, CT scan). In addition, false positive data were collected.

RESULTS

In total, 213 patients were retrieved, with 26 patients showing relapse (recurrence rate, 12.2%). The mean follow-up time was 3 years and the mean time to recurrence was 17.8 months. 21/26 (80.7%) recurrences were identified by the doctor and 5/26 (19.2%) by the patient (P < 0.05). Among those identified by the doctor, 16/21 (76,1%) were identified by radiological examinations. Nine out of 15 (60%) lymph node recurrences were detected by ultrasound and 6/7 (85.7%) distant metastases were detected by CT. The false positive rate was 7% (P < 0.05).

CONCLUSIONS

In our study the great majority of metastases were detected using imaging procedures. Given the new therapeutic options offered by targeted therapy and immunotherapy in relapsing patients, the role of radiological investigations in the follow-up of stage IIA patients should be reconsidered.

Diagnostic Performance of [18F]F-FDG Positron Emission Tomography (PET) in Non-Ophthalmic Malignant Melanoma: A Systematic Review and Meta-Analysis of More Than 10,000 Melanoma Patients

We described the diagnostic performance of [18F]F-FDG-PET in malignant melanoma by conducting a comprehensive systematic review and meta-analysis of the existing literature. The study was designed following PRISMA-DTA. Original articles with adequate crude data for meta-analytic calculations that evaluated [18F]F-FDG-PET and compared it with a valid reference standard were considered eligible. The pooled measurements were calculated based on the data level (patient/lesion-based). Regarding sub-groups, diagnostic performances were calculated for local, regional and distant involvement. The bivariate model was employed to calculate sensitivity and specificity. The initial search resulted in 6678 studies. Finally, 100 entered the meta-analysis, containing 82 patient-based (10,403 patients) and 32 lesion-based (6188 lesions) datasets. At patient level, overall, [18F]F-FDG-PET had pooled sensitivity and specificity of 81% (95%CI: 73-87%) and 92% (95%CI: 90-94%), respectively. To detect regional lymph node metastasis, the pooled sensitivity and specificity were 56% (95%CI: 40-72%) and 97% (95%CI: 94-99%), respectively. To detect distant metastasis, they were 88% (95%CI: 81-93%) and 94% (95%CI: 91-96%), respectively. At lesion level, [18F]F-FDG-PET had a pooled sensitivity and specificity of 70% (95%CI: 57-80%) and 94% (95%CI: 88-97%), respectively. Thus, [18F]F-FDG-PET is a valuable diagnostic modality for melanoma assessment. It was accurate in various clinical scenarios. However, despite its high specificity, it showed low sensitivity in detecting regional lymph node metastasis and could not replace lymph node biopsy.

Increased Thyroidal Activity on Routine FDG-PET/CT after Combination Immune Checkpoint Inhibition: Temporal Associations with Clinical and Biochemical Thyroiditis

BACKGROUND

FDG-PET/CT used for immune checkpoint inhibitor (ICI) response assessment can incidentally identify immune-related adverse events (irAEs), including thyroiditis. This study aimed to correlate the time course of FDG-PET/CT evidence of thyroiditis with clinical and biochemical evolution of thyroid dysfunction.

METHODS

A retrospective review was performed by two independent blinded nuclear medicine physicians (NMPs) of thyroidal FDG uptake in 127 patients who underwent PET/CT between January 2016 and January 2019 at baseline and during treatment monitoring of combination ICI therapy for advanced melanoma. Interobserver agreement was assessed and FDG-PET/CT performance defined by a receiver-operating characteristic (ROC) curve using thyroid function tests (TFTs) as the standard of truth. Thyroid maximum standardized uptake value (SUVmax) and its temporal changes with respect to the longitudinal biochemistry were serially recorded.

RESULTS

At a median of 3 weeks after commencing ICI, 43/127 (34%) had a diagnosis of thyroiditis established by abnormal TFTs. FDG-PET/CT was performed at baseline and at a median of 11 weeks (range 3-32) following the start of therapy. ROC analysis showed an area under the curve of 0.87 (95% CI 0.80, 0.94) for FDG-PET/CT for detection of thyroiditis with a positive predictive value of 93%. Among patients with biochemical evidence of thyroiditis, those with a positive FDG-PET/CT were more likely to develop overt hypothyroidism (77% versus 35%, p < 0.01). In the evaluation of the index test, there was an almost perfect interobserver agreement between NMPs of 93.7% (95% CI 89.4-98.0), kappa 0.83.

CONCLUSION

Increased metabolic activity of the thyroid on routine FDG-PET/CT performed for tumoral response of patients undergoing ICI therapy is generally detected well after routine biochemical diagnosis. Elevation of FDG uptake in the thyroid is predictive of overt clinical hypothyroidism and suggests that an ongoing robust inflammatory response beyond the initial thyrotoxic phase may be indicative of thyroid destruction.

Imaging for assessment of cancer treatment response to immune checkpoint inhibitors can be complementary in identifying hypophysitis

Introduction

Hypophysitis is reported in 8.5%-14% of patients receiving combination immune checkpoint inhibition (cICI) but can be a diagnostic challenge. This study aimed to assess the role of routine diagnostic imaging performed during therapeutic monitoring of combination anti-CTLA-4/anti-PD-1 treatment in the identification of hypophysitis and the relationship of imaging findings to clinical diagnostic criteria.

Methods

This retrospective cohort study identified patients treated with cICI between January 2016 and January 2019 at a quaternary melanoma service. Medical records were reviewed to identify patients with a documented diagnosis of hypophysitis based on clinical criteria. Available structural brain imaging with magnetic resonance imaging (MRI) or computed tomography (CT) of the brain and 2-deoxy-2-[18F]fluoro-D-glucose positron emission tomography with computed tomography (FDG-PET/CT) were assessed retrospectively. The main radiological outcome measures were a relative change in pituitary size or FDG uptake temporally attributed to cICI.

Results

There were 162 patients (median age 60 years, 30% female) included. A total of 100 and 134 had serial CT/MRI of the brain and FDG-PET/CT, respectively. There were 31 patients who had a documented diagnosis of hypophysitis and an additional 20 who had isolated pituitary imaging findings. The pituitary gland enlargement was mild, and the largest absolute gland size was 13 mm, with a relative increase of 7 mm from baseline. There were no cases of optic chiasm compression. Pituitary enlargement and increased FDG uptake were universally transient. High-dose glucocorticoid treatment for concurrent irAEs prevented assessment of the pituitary-adrenal axis in 90% of patients with isolated imaging findings.

Conclusion

Careful review of changes in pituitary characteristics on imaging performed for assessment of therapeutic response to iICI may lead to increased identification and more prompt management of cICI-induced hypophysitis.

Surveillance After a Previous Cutaneous Melanoma Diagnosis: A Scoping Review of Melanoma Follow-Up Guidelines

INTRODUCTION

Cutaneous melanoma accounts for more than 70% of all skin cancer deaths. Follow-up surveillance is an integral part of melanoma patient care, to facilitate early detection of recurrences and subsequent primary melanomas. The purpose of this scoping review is to provide an overview of recently published melanoma surveillance guidelines from regional and national melanoma working groups.

METHODS

A systematic search for relevant studies in MEDLINE and Embase was conducted in September 2022 and was limited to publications from 2010 or later.

RESULTS

A total of 1047 articles were retrieved, and after abstract and full text review, 26 articles from 19 different organizations met inclusion criteria. Life-long annual skin surveillance with a physician was recommended by 53% (9/17) of guidelines. Routine laboratory investigations were recommended by 7/19 guidelines. Regional lymph node ultrasound was recommended by 9/16 guidelines, most often in stage IB or higher, and was optional in 7/16 for patients who met specific criteria. Surveillance with PET-CT or CT and MRI was recommended by 15 and 11 guidelines, respectively, most commonly in stage IIC or higher, with a variable frequency and total duration. Five out of 9 guidelines indicated a preference for skin surveillance to be completed with a dermatologist.

CONCLUSION

Guidelines were highly variable for many aspects of melanoma surveillance, which may be partly attributed to regional differences in healthcare workforce distribution and availability of imaging technologies. Further high-level studies are recommended to provide more evidence on the most effective clinical and imaging follow-up surveillance protocols.

FDG PET/CT Prognostic Markers in Patients with Advanced Melanoma Treated with Ipilimumab and Nivolumab

Background Despite improved response to combined ipilimumab and nivolumab (hereafter, IpiNivo) treatment for advanced melanoma, many patients exhibit primary or acquired resistance. This, combined with high risk of immune-related adverse events, makes identifying markers predictive of outcomes desirable. Purpose To investigate the prognostic value of fluorine 18 (¹⁸F) fluorodeoxyglucose (FDG) PET/CT parameters at baseline and as part of response monitoring in patients with advanced melanoma undergoing IpiNivo treatment. Materials and Methods This was a single-center retrospective study of adult patients with melanoma who received IpiNivo. Baseline FDG PET/CT parameters that included metabolic tumor volume (MTV), tumor stage, mutation status, Eastern Cooperative Oncology Group performance score, lactate dehydrogenase level, and treatment line were correlated with overall survival in univariable and multivariable Cox regression analyses. Treatment response as determined with FDG PET/CT was correlated with overall survival. Results In total, 122 patients (median age, 61 years [IQR, 51-69 years]; 89 men) were included; 78% (95 of 122) had an Eastern Cooperative Oncology Group score of 0, 52% (45 of 86) had an elevated lactate dehydrogenase level, 39% (48 of 122) had a metastatic stage of M1c and 45% (55 of 122) M1d, 45% (55 of 122) had BRAF V600E/K mutation, and the median MTV was 42 mL. Patients with a higher than median MTV at baseline FDG PET/CT had a lower 12-month survival rate compared with those with a lower than median MTV (43% [95% CI: 32, 58] vs 66% [95% CI: 55, 79], P < .001). In multivariable analysis, higher versus lower than median MTV, Eastern Cooperative Oncology Group performance scores of 1-2 versus 0, and subsequent versus first-line IpiNivo treatment were independently associated with overall survival (hazard ratio [HR]: 1.68 [95% CI: 1.02, 2.78], P = .04; 3.1 [95% CI: 1.8, 5.4], P < .001; and 11.2 [95% CI: 3.4, 37.1], P = .002, respectively). The 12-month overall survival rate was lower in patients with progressive disease than in those without progression (35% [95% CI: 24, 51] vs 90% [95% CI: 83, 99]; HR, 7.3 [95% CI: 3.9, 13.3]; P < .001). Conclusion Baseline fluorine 18 fluorodeoxyglucose PET/CT metabolic tumor volume was an independent prognostic marker in patients with advanced melanoma who received ipilimumab and nivolumab treatment. © RSNA, 2023 Supplemental material is available for this article.

The Impact of Surveillance Imaging Frequency on the Detection of Distant Disease for Patients with Resected Stage III Melanoma

BACKGROUND

It is not known whether there is a survival benefit associated with more frequent surveillance imaging in patients with resected American Joint Committee on Cancer stage III melanoma.

OBJECTIVE

The aim of this study was to investigate distant disease-free survival (DDFS), melanoma-specific survival (MSS), post distant recurrence MSS (dMSS), and overall survival for patients with resected stage III melanoma undergoing regular computed tomography (CT) or positron emission tomography (PET)/CT surveillance imaging at different intervals.

PATIENTS AND METHODS

A closely followed longitudinal cohort of patients with resected stage IIIA-D disease treated at a tertiary referral center underwent 3- to 4-monthly, 6-monthly, or 12-monthly surveillance imaging between 2000 and 2017. Survival outcomes were estimated using the Kaplan-Meier method, and log-rank tests assessed the significance of survival differences between imaging frequency groups.

RESULTS

Of 473 patients (IIIA, 19%; IIIB, 31%; IIIC, 49%; IIID, 1%) 30% underwent 3- to 4-monthly imaging, 10% underwent 6-monthly imaging, and 60% underwent 12-monthly imaging. After a median follow-up of 6.2 years, distant recurrence was recorded in 252 patients (53%), with 40% detected by surveillance CT or PET/CT, 43% detected clinically, and 17% with another imaging modality. Median DDFS was 5.1 years (95% confidence interval 3.9-6.6). Among 139 IIIC patients who developed distant disease, the median dMSS was 4.4 months shorter in those who underwent 3- to 4-monthly imaging than those who underwent 12-monthly imaging.

CONCLUSION

Selecting patients at higher risk of distant recurrence for more frequent surveillance imaging yields a higher proportion of imaging-detected distant recurrences but is not associated with improved survival. A randomized comparison of low versus high frequency imaging is needed.

Follow-up of primary melanoma patients with high risk of recurrence: recommendations based on evidence and consensus

In spite of the good prognosis of patients with early-stage melanoma, there is a substantial proportion of them that develop local or distant relapses. With the introduction of targeted and immune therapies for advanced melanoma, including at the adjuvant setting, early detection of recurrent melanoma and/or second primary lesions is crucial to improve clinical outcomes. However, there is a lack of universal guidelines regarding both frequency of surveillance visits and diagnostic imaging and/or laboratory evaluations. In this article, a multidisciplinary expert panel recommends, after careful review of relevant data in the field, a consensus- and experience-based follow-up strategy for melanoma patients, taking into account prognostic factors and biomarkers and the high-risk periods and patterns of recurrence in each (sub) stage of the disease. Apart from the surveillance intensity, healthcare professionals should focus on patients' education to perform regular self-examinations of the skin and palpation of lymph nodes.

Yield of baseline imaging for distant metastases in high-risk primary melanoma

BACKGROUND

The yield of baseline imaging in patients presenting with higher risk primary tumours, at least American Joint Committee on Cancer 8th edition stage IIC or III melanoma, is unclear.

METHODS

This retrospective study included patients referred to the Victorian Melanoma Service from January 2017 to April 2020, diagnosed with at least stage IIC or stage III melanoma. Patients with a T4b tumour and no sentinel lymph node biopsy were included as 'T4bNX'.

RESULTS

One hundred and sixty-four patients (median age 65 years) with baseline imaging (T4bNX: 19, IIC: 30, IIIA: 21, IIIB: 43, IIIC: 50, IIID: 1) were included. The majority were male (73%), and those with T4bNX melanoma tended to be older (median age 79 years). Distant metastases were detected in 21% (4/19) of T4bNX, 3% (1/30) of stage IIC, 0% (0/21) of stage IIIA, and 6% (6/94) of stages IIIB-D melanoma patients. All stage III patients with distant metastases had palpable lymphadenopathy a presentation. Two patients had brain metastases, both of whom had T4bNX melanoma and synchronous extra-cranial metastases.

CONCLUSIONS

Compared to stage IIC, baseline imaging detects higher rates of extra-cranial distant disease in stages IIIB-D and T4bNX melanoma. Intracranial imaging has greater yield in patients with distant extra-cranial disease.

18 F-FDG positron emission tomography-computed tomography has a low positive predictive value for detecting occult recurrence in asymptomatic patients with high-risk Stages IIB, IIC, and IIIA melanoma

BACKGROUND AND OBJECTIVES

High recurrence rates of Stages II and IIIA melanoma make close follow-up essential, especially with new adjuvant therapies for metastatic disease. However, there are currently no consensus guidelines for routine imaging for Stages IIB, IIC, and IIIA melanoma. The study's aim is to determine the utility of 18 F-fluorodeoxyglucose (18 F-FDG) positron emission tomography/computed tomography (PET/CT) for detecting asymptomatic recurrence of melanoma after primary surgical resection.

METHODS

This retrospective cohort study included 158 patients with the American Joint Committee on Cancer 8th edition Stages IIB, IIC, or IIIA cutaneous melanoma who underwent an 18 F-FDG PET/CT from 2010 to 2020. We retrospectively analyzed clinical data after a median follow-up time of 39 months.

RESULTS

We calculated a positive predictive value (PPV) of 32% (95% confidence interval: 11%-53%) for 154 routine PET/CTs, including six true positives and 13 false positives (FPs). PPV was 33% for Stage IIB, 50% for Stage IIC, and 14% for Stage IIIA. FPs were mostly benign or inflammatory foci (75%), and some other malignancies were found (21%).

CONCLUSIONS

This cohort of patients imaged for high-risk melanoma demonstrated a high FP rate and low PPV. These findings suggest that routine surveillance with 18 F-FDG PET/CT may not be indicated for monitoring recurrence in this population.

Quality of Life in the First Year of Follow-Up in a Randomized Multicenter Trial Assessing the Role of Imaging after Radical Surgery of Stage IIB-C and III Cutaneous Melanoma (TRIM Study)

The benefit of imaging in the follow-up setting for high-risk melanoma patients is uncertain, and even less is known about the impact of intensive follow-up on the patient´s quality of life. In 2017, a Swedish prospective randomized multicenter study started, in which high-risk melanoma patients are randomly assigned 1:1 to follow-up by physical examinations +/- whole-body imaging. The first-year examinations are scheduled at 0, 6 and 12 months. The aim of this study was to investigate whether the patients´ health-related quality of life (HRQoL) and levels of anxiety and depression were affected at 1 year by imaging. Anxiety/depression and HRQoL were assessed at 0 and 12 months by the questionnaires Hospital Anxiety and Depression (HAD) scale and EORTC QLQ-C30 version 3. Expected baseline QLQ-C30 values for the patients were calculated using data from the general population. In total, 204 patients were analyzed. Mean differences in subscale scores at 1 year were not statistically significant either for HRQoL or for anxiety/depression. Baseline HRQoL did not differ from expected values in the general Swedish population. In conclusion, the patients in general coped well with the situation, and adding whole-body imaging to physical examinations did not affect the melanoma patients' HRQoL or levels of anxiety or depression.

FDG-PET to predict long-term outcome from anti-PD-1 therapy in metastatic melanoma

BACKGROUND

We have previously shown that 75% of patients treated with programmed cell death protein 1 (PD-1) with or without CTLA4 who have not progressed by 1 year have complete metabolic response (CMR), including two-thirds of patients with partial response (PR). We now report 5-year outcomes.

PATIENTS AND METHODS

Retrospective analysis of 104 patients with baseline and 1-year positron emission tomography (PET) and computed tomography (CT). The 1-year response was determined using RECIST for CT and European Organisation for Research and Treatment of Cancer (EORTC) criteria for PET. Progression-free survival (PFS) and overall survival (OS) were determined from the 1-year landmark.

RESULTS

At the median follow-up of 61 months (range 58-64 months) from 1-year PET, 94% remained alive and all but one had discontinued treatment after a median treatment duration of 23 months (range 1-59 months). Disease progression occurred in 19 patients (18%): 10 (53%) while on treatment and 12 (63%) in solitary sites for which 8 (67%) received local treatment. RECIST PFS rate at 5 years after PET was higher in complete response (CR) compared with PR/stable disease (SD) (93% versus 76%, respectively) and CMR compared with non-CMR (90% versus 54%, respectively). In patients with PR, 5-year PFS rate was superior in CMR (88% and 59%). A total of 35 (34%) patients (14/29 in CR, 31/78 in CMR) discontinued treatment within 12 months, largely due to toxicity, with no impact on PFS rate compared with those that continued (84% versus 78%). Despite progression events, OS rate at 5 years was excellent and similar in patients with CR and PR/SD (100% versus 91%, respectively) as well as in those with CMR and non-CMR (96% versus 87%, respectively).

CONCLUSIONS

Five years after the 1-year PET, sustained responses are observed in the majority of patients, particularly in those with CMR. PET continues to predict progression better than CT, particularly in those with residual disease on CT. In the minority that progress, often in solitary sites and managed locally, OS rate remains excellent. PET is effective in evaluating residual lesions on CT and can predict long-term benefit.

Precision Nuclear Medicine: The Evolving Role of PET in Melanoma

The clinical management of melanoma patients has been rapidly evolving with the introduction of new targeted immuno-oncology (IO) therapeutics. The current diagnostic paradigms for melanoma patients begins with the histopathologic confirmation of melanoma, initial staging of disease burden with imaging and surgical approaches, treatment monitoring during systemic cytotoxic chemotherapy or IO therapeutics, restaging after completion of adjuvant systemic, surgical, and/or external radiation therapy, and the detection of recurrent malignancy/metastatic disease following therapy. New and evolving imaging approaches with positron-emission tomography (PET) imaging technologies, imaging methodologies, image reconstruction, and image analytics will likely continue to improve tumor detection, tumor characterization, and diagnostic confidence, enabling novel precision nuclear medicine practices for managing melanoma patients. This review will examine current concepts and challenges with existing PET imaging diagnostics for melanoma patients and introduce exciting new opportunities for PET in the current era of IO therapeutics.

Pitfalls on PET/CT Due to Artifacts and Instrumentation

PET/CT has become a preferred imaging modality over PET-only scanners in clinical practice. However, along with the significant improvement in diagnostic accuracy and patient throughput, pitfalls on PET/CT are reported as well. This review provides a general overview on the potential influence of the limitations with respect to PET/CT instrumentation and artifacts associated with the modality integration on the image appearance and quantitative accuracy of PET. Approaches proposed in literature to address the limitations or minimize the artifacts are discussed as well as their current challenges for clinical applications. Although the CT component can play an important role in assisting clinical diagnosis, we concentrate on the imaging scenarios where CT is used to provide auxiliary information for attenuation compensation and scatter correction in PET.

Canadian Melanoma Conference Recommendations on High-Risk Melanoma Surveillance: A Report from the 14th Annual Canadian Melanoma Conference; Banff, Alberta; 20-22 February 2020

Introduction: There are a lack of established guidelines for the surveillance of high-risk cutaneous melanoma patients following initial therapy. We describe a novel approach to the development of a national expert recommendation statement on high-risk melanoma surveillance (HRS). Methods: A consensus-based, live, online voting process was undertaken at the 13th and 14th annual Canadian Melanoma Conferences (CMC) to collect expert opinions relating to “who, what, where, and when” HRS should be conducted. Initial opinions were gathered via audience participation software and used as the basis for a second iterative questionnaire distributed online to attendees from the 13th CMC and to identified melanoma specialists from across Canada. A third questionnaire was disseminated in a similar fashion to conduct a final vote on HRS that could be implemented. Results: The majority of respondents from the first two iterative surveys agreed on stages IIB to IV as high risk. Surveillance should be conducted by an appropriate specialist, irrespective of association to a cancer centre. Frequency and modality of surveillance favoured biannual visits and Positron Emission Tomography Computed Tomography (PET/CT) with brain magnetic resonance imaging (MRI) among the systemic imaging modalities available. No consensus was initially reached regarding the frequency of systemic imaging and ultrasound of nodal basins (US). The third iterative survey resolved major areas of disagreement. A 5-year surveillance schedule was voted on with 92% of conference members in agreement. Conclusion: This final recommendation was established following 92% overall agreement among the 2020 CMC attendees.

Early Reassessment of Total Metabolic Tumor Volume on FDG-PET/CT in Advanced Melanoma Patients Treated with Pembrolizumab Predicts Long-Term Outcome

PD-1 Immune checkpoint inhibitors, such as Pembrolizumab, can have a durable beneficial therapeutic effect in patients with advanced melanoma. However, not all patients will benefit equally from these therapies, and (potentially life-threatening) immune-related adverse events may occur. In this study, we investigate the value of early response assessment by FDG-PET/CT as a biomarker for predicting survival. We identified all patients with advanced melanoma who were treated with Pembrolizumab in our medical center and underwent a baseline and at least one follow-up FDG-PET/CT. The total metabolic tumor volume (TMTV) was calculated, and the evolution was compared to survival parameters. A total of 77 patients underwent a baseline and at least one follow-up FDG-PET/CT, 36 patients had follow-up imaging within 2–4 months, and 21 patients an FDG-PET/CT 5–6 months after baseline. When the TMTV evolution was categorized into two subgroups (stable/decrease versus increase), an association was found between stability or decrease in TMTV and better PFS and OS. A similar trend, however non-significant, was observed at 5–6 months. The evolution in TMTV as assessed by FDG-PET/CT 2–4 months after treatment initiation is associated with long-term outcomes in patients with advanced melanoma treated with Pembrolizumab.

TRIM study protocol - a prospective randomized multicenter Trial to assess the Role of Imaging during follow-up after radical surgery of stage IIB-C and III cutaneous malignant Melanoma

BACKGROUND

The incidence of cutaneous malignant melanoma (CMM) is increasing worldwide. In Sweden, over 4600 cases were diagnosed in 2018. The prognosis after radical surgery varies considerably with tumor stage. In recent years, new treatment options have become available for metastatic CMM. Early onset of treatment seems to improve outcome, which suggests that early detection of recurrent disease should be beneficial. Consequently, in several countries imaging is a part of the routine follow-up program after surgery of high risk CMM. However, imaging has drawbacks, including resources required (costs, personnel, equipment) and the radiation exposure. Furthermore, many patients experience anxiety in waiting for the imaging results and investigations of irrelevant findings is another factor that also could cause worry and lead to decreased quality of life. Hence, the impact of imaging in this setting is important to address and no randomized study has previously been conducted. The Swedish national guidelines stipulate follow-up for 3 years by clinical examinations only.

METHODS

The TRIM study is a prospective randomized multicenter trial evaluating the potential benefit of imaging and blood tests during follow-up after radical surgery for high-risk CMM, compared to clinical examinations only. Primary endpoint is overall survival (OS) at 5 years. Secondary endpoints are survival from diagnosis of relapse and health-related quality of life (HRQoL). Eligible for inclusion are patients radically operated for CMM stage IIB-C or III with sufficient renal function for iv contrast-enhanced CT and who are expected to be fit for treatment in case of recurrence. The planned number of patients is > 1300. Patients are randomized to clinical examinations for 3 years +/- whole-body imaging with CT or FDG-PET/CT and laboratory tests including S100B protein and LDH. This academic study is supported by the Swedish Melanoma Study Group.

DISCUSSION

This is the first randomized prospective trial on the potential benefit of imaging as a part of the follow-up scheme after radical surgery for high-risk CMM.

RESULTS

The first patient was recruited in June 2017 and as of April 2020, almost 500 patients had been included at 19 centers in Sweden.

TRIAL REGISTRATION

ClinicalTrials.gov , NCT03116412 . Registered 17 April 2017, https://clinicaltrials.gov/ct2/show/study/NCT03116412.

The utility of initial staging PET-CT as a baseline scan for surveillance imaging in stage II and III melanoma

BACKGROUND

This study evaluates the utility of whole-body PET-CT for the initial staging and subsequent surveillance imaging of patients with completely resected stage II and stage III melanoma.

METHODS

A single-center, retrospective review of patients who received perioperative whole-body PET-CT from January 1, 2005 to December 1, 2019 within three months of initial melanoma diagnosis was performed.

RESULTS

Of 258 total patients with completely resected melanoma who had a PET-CT within 3 months after their melanoma diagnosis, 113 had stage II and 145 had stage III melanoma. PET-CT detected distant metastasis in 3 (2.7%) of 113 stage II patients and 7 (4.8%) of 145 stage III patients. 179 of 258 patients had adequate follow-up time to determine whether they received surveillance cross-sectional imaging and whether they had a melanoma recurrence. 143 (79.9%) received subsequent surveillance imaging, 74 of whom developed a recurrence. In 64 (86.5%) of 74 cases, recurrence was detected by routine surveillance. 26 (34.2%) of 76 stage II and 65 (63.1%) of 103 stage III patients developed a recurrence. The median time to recurrence among the 179 patients for stage II and III was 16.3 and 13.0 months, respectively.

CONCLUSIONS

These findings indicate that baseline staging with whole-body PET-CT rarely provides information that changes initial management. Rather, the value of the initial PET-CT is as a baseline for subsequent surveillance scans. Therefore, it may be premature to discourage cross-sectional imaging for patients with stage II and III melanoma without supportive evidence or a reliable biomarker of recurrent disease.

18F-fluorodeoxyglucose Positron Emission Tomography/Computed Tomography for Assessing Tumor Response to Immunotherapy in Solid Tumors: Melanoma and Beyond

The complexity of the immune response and diversity of targets challenges conventional conceptual frameworks used in selecting and monitoring treatment with immune check-point inhibitors. The limitations of anatomic imaging in assessing response have been recognized. Varying patterns of response have been recognized. These patterns have different implications for the continuation and duration of therapy. Evidence supporting the role of ¹⁸F-fluorodeoxyglucose Positron Emission Tomography/Computed Tomography as a prognostic biomarker and in characterizing response is presented. An added benefit of this approach is the ability to detect immune-related inflammatory reactions, often in advance of severe or life-threatening clinical manifestations.

18F-FDG PET/CT based spleen to liver ratio associates with clinical outcome to ipilimumab in patients with metastatic melanoma

Background

Immune checkpoint blockade such as ipilimumab and anti-PD1 monoclonal antibodies have significantly improved survival in advanced melanoma. Biomarkers are urgently needed as a majority of patients do not respond, despite treatment-related toxicities. We analysed pre-treatment ¹⁸F-fluorodeoxyglucose positron emission tomography/computerised tomography (FDG PET/CT) parameters to assess its correlation with patient outcome.

Methods

This retrospective study evaluated pre-treatment FDG PET/CT scans in a discovery cohort of patients with advanced melanoma treated with ipilimumab or anti-PD1. Pre-treatment scans were assessed for maximum tumoral standardised uptake value (SUVmax), metabolic tumour volume (MTV) and spleen to liver ratio (SLR). Progression-free survival (PFS) and overall survival (OS) were characterised and modelled using univariable and multivariable analyses. Correlation of SLR and OS was validated in an independent cohort. Blood parameters and stored sera of patients from the discovery cohort was analysed to investigate biological correlates with SLR.

Results

Of the 90 evaluable patients in the discovery cohort: 50 received ipilimumab monotherapy, 20 received anti-PD1 monotherapy, and 20 patients received ipilimumab followed by anti-PD1 upon disease progression. High SLR > 1.1 was associated with poor PFS (median 1 vs 3 months; HR 3.14, p = 0.008) for patients treated with ipilimumab. High SLR was associated with poor OS after ipilimumab (median 1 vs 21 months; HR 5.83, p = 0.0001); as well as poor OS after first line immunotherapy of either ipilimumab or anti-PD1 (median 1 vs 14 months; HR 3.92, p = 0.003). The association of high SLR and poor OS after ipilimumab was validated in an independent cohort of 110 patients (median 2.3 months versus 11.9 months, HR 3.74). SLR was associated with poor OS in a multi-variable model independent of stage, LDH, absolute lymphocyte count and MTV.

Conclusions

Pre-treatment Spleen to liver ratio (SLR) > 1.1 was associated with poor outcome after ipilimumab in advanced melanoma. This parameter warrants prospective evaluation.

FDG PET/CT for tumoral and systemic immune response monitoring of advanced melanoma during first-line combination ipilimumab and nivolumab treatment

PURPOSE

We aimed to investigate the role of FDG-PET/CT in monitoring of response and immune-related adverse events (irAEs) following first-line combination-immune checkpoint inhibitor (combination-ICI) therapy for advanced melanoma.

METHODS

We retrospectively reviewed outcomes in patients who had (1) first-line nivolumab plus ipilimumab; (2) pre- and post-treatment FDG-PET/CT scans (pre-FDG-PET/CT and post-FDG-PET/CT) within 2 and 4 months of starting ICI, respectively; and (3) at least one lesion assessable by PET response criteria in solid tumors (PERCIST). Extracranial response was monitored by 3 monthly FDG-PET/CT. Whole-body metabolic tumor volume (wbMTV) was measured pre- and post-treatment and correlated with outcome. FDG-PET/CT manifestations of irAE were defined as new increased non-tumoral uptake on post-FDG-PET/CT and were correlated with clinical presentation.

RESULTS

Thirty-one consecutive patients, median age 60 years (range, 30-78), were identified from 2016 to 2018. The median number of combination-ICI cycles to the first post-FDG-PET/CT response assessment was 3 (interquartile range (IQR), 2-4). The best-overall responses were complete metabolic response (CMR) in 25 (80%), partial metabolic response (PMR) in 3 (10%), and progressive metabolic disease (PMD) in 3 (10%) patients. Patients with PMD had significantly higher pre-treatment wbMTV (p = 0.009). At a median follow-up of 21.5 months, 26 (84%) patients were alive with median progression-free and overall survival not reached. Secondary progression occurred in 9/31 (29%) patients at a median of 8.2 months (IQR, 6.9-15.5), of those majority (78%) was detected by FDG-PET/CT. Of 36 findings on post-FDG-PET/CT suggestive of irAE, 29 (80%) had clinical confirmation. In 3 (7%), the FDG-PET/CT findings preceded clinical presentation. The most common FDG-PET/CT detectable irAEs were endocrinopathies (36%) and enterocolitis (35%).

CONCLUSION

FDG-PET/CT response evaluation predicts the long-term outcome of patients treated with first-line combination-ICIs. Long-term treatment response monitoring for detection of extracranial secondary progression is feasible by FDG-PET/CT. Beyond response assessment, FDG-PET/CT frequently detects clinically relevant irAEs, which may involve multiple systems contemporaneously or at various time-points and may precede clinical diagnosis.

FDG PET Hybrid Imaging

Molecular imaging with positron emission tomography (PET) using tumour-seeking radiopharmaceuticals has gained wide acceptance in oncology with many clinical applications. The hybrid imaging modality PET/CT (computed tomography) allows assessing molecular as well as morphologic information at the same time. Therefore, PET/CT represents an efficient tool for whole-body staging and re-staging within one imaging modality. In oncology, the glucose analogue 18-F-fluorodeoxyglucose (FDG) is the most widely used PET/CT radiopharmaceutical in clinical routine. FDG PET and FDG PET/CT have been used for staging and re-staging of tumour patients in numerous studies. This chapter will discuss the use and the main indications of FDG PET/CT in oncology with special emphasis on lung cancer, lymphoma, head and neck cancer, melanoma and breast cancer (among other tumour entities). A review of the current literature is given with respect to primary diagnosis, staging and diagnosis of recurrent disease. Besides its integral role in diagnosis, staging and re-staging of disease in oncology, there is increasing evidence that FDG PET/CT can be used for therapy response assessment (possibly influencing therapeutic management and treatment planning) by evaluating tumour control, which will also be discussed in this chapter.

Clinical and Prognostic Value of 18F-FDG-PET/CT in the Restaging Process of Recurrent Cutaneous Melanoma

BACKGROUND

Several studies on 18F-FDG-PET/CT have investigated the prognostic role of this imaging modality in different tumors after treatment. Nevertheless, its role in restaging patients with recurrent CM still needs to be defined.

OBJECTIVE

The aim of this retrospective multicenter study was to evaluate the clinical and prognostic impact of 18F-FDG-PET/CT on the restaging process of cutaneous melanoma (CM) after surgery in patients with suspected distant recurrent disease or suspected metastatic progression disease.

MATERIALS AND METHODS

74 patients surgically treated for CM underwent 18F-FDG-PET/CT for suspected distant recurrent disease or suspected metastatic progression disease. The diagnostic accuracy of visually interpreted 18F-FDG-PET/CT was obtained by considering histology (n=21 patients), other diagnostic imaging modalities performed within 2 months of PET/CT (CT in 52/74 patients and Whole-Body MRI in 18/74 patients) and clinical follow-up (n=74 patients) for at least 24 months containing all the clinical and diagnostic information useful for the PET performance assessment and outcome. Progression-free survival (PFS) and overall survival (OS) were assessed by using the Kaplan- Meier method. The risk of progression (Hazard Ratio-HR) was computed by the Cox regression analysis.

RESULTS

Suspicion of recurrent CM was confirmed in 24/27 patients with a positive 18F-FDG-PET/CT scan. Overall, the sensitivity, specificity, positive predictive value, negative predictive value and accuracy of 18F-FDG-PET/CT were 82%, 93%, 88%, 89%, and 89%, respectively, with area under the curve being 0.87 (95%IC 0.78-0.97; p<0.05). 18F-FDG-PET/CT findings significantly influenced the therapeutic management in 18 patients (modifying therapy in 10 patients; guiding surgery in 8 patients). After 2 years of follow-up, PFS was significantly longer in patients with a negative vs. a positive 18F-FDG-PET/CT scan (90% vs 46%, p<0.05; Fig. 1). Moreover, a negative scan was associated with a significantly longer OS than a positive one (76% vs 39% after 2 years, p<0.05; Fig. 2). In addition, a positive 18F-FDG-PET/CT scan was associated with an increased risk of disease progression (HR=8.2; p<0,05).

CONCLUSION

18F-FDG-PET/CT showed a valuable diagnostic performance in patients with suspicion of recurrent CM. This imaging modality might have an important prognostic value in predicting the survival outcomes, assessing the risk of disease progression, and guiding treatment decision making.

S-100B as an extra selection tool for FDG PET/CT scanning in follow-up of AJCC stage III melanoma patients

Background and Objectives

This current study assessed the value of S‐100B measurement to guide fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) scanning for detecting recurrent disease in stage III melanoma patients.

Methods

This study included 100 stage III melanoma patients in follow‐up after curative lymph node dissection. Follow‐up visits included physical examination and S‐100B monitoring. FDG PET/CT scanning was indicated by clinical symptoms and/or elevated S‐100B.

Results

Of 100 patients, 13 (13%) had elevated S‐100B without clinical symptoms, of whom 7 (54%) showed disease evidence upon FDG PET/CT scanning. Twenty‐six patients (26%) had clinical symptoms with normal S‐100B and FDG PET/CT revealed metastasis in 20 (77%). Three patients had clinical symptoms and elevated S‐100B, and FDG PET/CT revealed metastasis in all three (100%). Overall, FDG PET/CT scanning revealed metastasis in 30 of the 42 patients (71.4%). For seven recurrences, elevated S‐100B prompted early detection of asymptomatic disease; 10% of all asymptomatic patients in follow‐up, 23% of all patients with recurrent disease.

Conclusion

S‐100B cannot exclude recurrent disease during follow‐up of stage III melanoma. However, adding S‐100B measurement to standard clinical assessment can guide FDG PET/CT scanning for detecting recurrent melanoma.

Prediction and monitoring of relapse in stage III melanoma using circulating tumor DNA

BACKGROUND

The advent of effective adjuvant therapies for patients with resected melanoma has highlighted the need to stratify patients based on risk of relapse given the cost and toxicities associated with treatment. Here we assessed circulating tumor DNA (ctDNA) to predict and monitor relapse in resected stage III melanoma.

PATIENTS AND METHODS

Somatic mutations were identified in 99/133 (74%) patients through tumor tissue sequencing. Personalized droplet digital PCR (ddPCR) assays were used to detect known mutations in 315 prospectively collected plasma samples from mutation-positive patients. External validation was performed in a prospective independent cohort (n = 29).

RESULTS

ctDNA was detected in 37 of 99 (37%) individuals. In 81 patients who did not receive adjuvant therapy, 90% of patients with ctDNA detected at baseline and 100% of patients with ctDNA detected at the postoperative timepoint relapsed at a median follow up of 20 months. ctDNA detection predicted patients at high risk of relapse at baseline [relapse-free survival (RFS) hazard ratio (HR) 2.9; 95% confidence interval (CI) 1.5-5.6; P = 0.002] and postoperatively (HR 10; 95% CI 4.3-24; P < 0.001). ctDNA detection at baseline [HR 2.9; 95% CI 1.3-5.7; P = 0.003 and postoperatively (HR 11; 95% CI 4.3-27; P < 0.001] was also associated with inferior distant metastasis-free survival (DMFS). These findings were validated in the independent cohort. ctDNA detection remained an independent predictor of RFS and DMFS in multivariate analyses after adjustment for disease stage and BRAF mutation status.

CONCLUSION

Baseline and postoperative ctDNA detection in two independent prospective cohorts identified stage III melanoma patients at highest risk of relapse and has potential to inform adjuvant therapy decisions.

Early Recurrence in Completely Resected IIIB and IIIC Melanoma Warrants Restaging Prior to Adjuvant Therapy

Purpose

To evaluate the results of restaging completely resected stage IIIB/C melanoma prior to start of adjuvant therapy.

Patients and Methods

One hundred twenty patients with stage IIIB or IIIC (AJCC 2009) melanoma who underwent complete surgical resection were screened for inclusion in our trial investigating adjuvant dendritic cell therapy (NCT02993315). All patients underwent imaging to exclude local relapse or metastasis before entering the trial. The frequency of recurrent disease within 12 weeks after resection and the method of detection were investigated.

Results

Sixty-nine (58%) stage IIIB and 51 (43%) stage IIIC melanoma patients were screened. Median age was 54 (range 27–79) years. Twenty-two (18%) of 120 patients with completely resected stage IIIB/C melanoma had evidence of early recurrent disease, despite exclusion thereof by prior imaging. Median interval between resection and detection of relapse was 7.4 (range 4.3–10.7) weeks. Recurrence was asymptomatic in 17 (77%) patients, but metastasis was noticed by the patient or physician in 5 (23%). Eight patients with local relapse received local treatment with curative intent, and one was treated with systemic therapy. The remaining patients had distant metastasis, 1 of whom underwent resection of a solitary liver metastasis while 12 patients received systemic treatment.

Conclusions

Patients with completely resected stage IIIB/C melanoma have high risk of early recurrence before start of adjuvant therapy. Restaging should be considered for high-risk melanoma patients before start of adjuvant therapy.

Surveillance imaging for metastasis in high-risk melanoma: importance in individualized patient care and survivorship

Most patients newly diagnosed with melanoma have early-stage disease considered of good prognosis. However, with a risk of recurrence, appropriate follow-up may include surveillance imaging for early relapse detection. Previously, surveillance imaging to detect recurrences was considered unjustified, given the lack of effective treatments. Now, systemic therapies have improved, and patients with low tumor burden may derive benefit from surveillance imaging. Despite this, controversy exists regarding the role of surveillance imaging in early-stage melanoma survivorship, in part reflected by the lack of consensus on specific imaging protocols and broad guidelines. This review discusses published evidence on surveillance imaging to detect metastasis in high-risk melanoma, the need for early recurrence detection and implications for value-based clinical decision-making, survivorship care and multidisciplinary patient management.

Recurrence of Melanoma After Initial Treatment: Diagnostic Performance of FDG PET in Posttreatment Surveillance

Purpose

In malignant melanoma, recurrence is often observed in distant areas from the primary site. While FDG PET is a sensitive imaging for detecting malignant lesions, the role of FDG PET in posttreatment surveillance period has not been investigated sufficiently. The aim of this study was to evaluate the value of PET during posttreatment surveillance in melanoma.

Methods

A total of 76 melanoma patients who underwent FDG PET during surveillance period after completion of the first treatment were retrospectively enrolled. PET scans were grouped according to the purpose and clinical situations, routine surveillance, or evaluating clinical suspicion. Final diagnosis of recurrence was determined by complete clinical evaluation or long-term follow-up. In each situation, the diagnostic role of FDG PET was assessed.

Results

A total of 143 scans of 76 patients were analyzed: 51 for clinical suspicion and 92 for routine surveillance. In the clinical suspicion group, PET correctly diagnosed non-recurrence in 10 cases (20%). In routine surveillance group, 16 cases (17%) presented recurrence, all of which was correctly diagnosed on PET. NPV and PPV were 100% and 76%, respectively. In subgroup analysis, sensitivity and NPV were higher in the low-risk group (stages I-II_A) than in the high-risk group (stages II_B-IV), while specificity and PPV were higher in the high-risk group.

Conclusion

In conclusion, FDG PET is an effective diagnostic tool in posttreatment surveillance of melanoma. Even in cases without clinical suspicion, melanoma recurs in a considerable proportion of patients, which can be sensitively diagnosed on PET.