Clinical value of whole body 18F-FDG PET/CT imaging in patients with cutaneous melanoma: A multi-center cohort study.

BACKGROUND: 18F-FDG-PET/CT is a valuable tool in the staging and surveillance of cutaneous melanoma; however, recent studies prompt debate on the clinical significance of imaging patients below the lesser trochanter. This study explored two research questions. In patients with a known primary cutaneous melanoma within the standard field of view (SFOV, between the orbits and lesser trochanter), what is the prevalence of metastasis to sites solely within the lower extremities? and, In patients with a known primary cutaneous melanoma within the SFOV what demographic and clinical factors are associated with sole metastasis to the lower extremities? METHODS: A retrospective, multi-centered, observational study of consecutive case reports was conducted. Subjects included 619 patients who underwent extended field of view (EFOV) 18F-FDG-PET/CT (from vertex to toes) for staging and/or follow-up of cutaneous melanoma. Data was collected at three primary healthcare centers in Canada (Nova Scotia, Alberta, and British Columbia). Inclusion criteria were patients >18 years of age, confirmed primary cutaneous melanoma, and a known location of the primary within the SFOV. Patients with primary cutaneous melanoma lesions in lower extremities and previous other cancers were excluded. To determine the prevalence of lesions located below the lesser trochanter, the proportion of such lesions were computed, and 95% confidence intervals ensured a precise estimation of the proportion. RESULTS: 2512 patient charts were reviewed with 619 meeting the inclusion criteria, 298 of these were females. Six percent had metastases in both the lower extremities and sites within the SFOV. The number of subjects who had no metastasis within their SFOV was 361 (58.3%). The number of subjects who presented with confirmed metastasis in the lower extremities without concurrent metastasis in the SFOV region was one (0.58%). Despite a large initial study sample, the number of patients with metastasis in the lower extremities was insufficient to allow correlation of factors associated with risk of spread to the lower extremities. CONCLUSION: Lower extremity 18F-FDG-PET/CT provided additional, relevant clinical data in a sole patient. This finding supports prior research suggesting the prevalence is rare. Future studies should seek to define demographic and clinical factors that predict such rare occurrences, where follow up would be warranted. This study highlights feasibility challenges associated with such investigation.

The Pathogenesis and Clinical Management of Cutaneous Melanoma: An Evidence-Based Review.

Cutaneous malignant melanoma (CM) is the leading cause of skin cancer-related mortality and accounts for approximately 1,250 deaths in Canada each year. It is also one of few cancers continuing to display rates of increasing incidence throughout the world. The past decade has brought significant growth in our understanding of the pathogenesis and clinical management of CM. This evidence-based review synthesizes that knowledge, beginning with a review of the epidemiology and etiology of the disease followed by a broad review of the roles of diagnostic imaging in its management. Special attention is given to the role of 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography-computed tomography (PET/CT) in supporting assessment at primary presentation of disease, follow-up to surgical and nonsurgical treatment, and for the surveillance of high-risk asymptomatic patients. After a brief review of current treatment options, this article concludes with a demonstration of how and when uncertainty exists at the point of care systematic review processes may be used to resolve clinical questions. Learning Objectives: By the end of this Continuing Medical Education article, participants will be able to 1. Describe the epidemiology and etiology of cutaneous melanoma, 2. Describe broadly the role of diagnostic imaging in the clinical management of cutaneous melanoma, 3. Describe the specific roles and limitations of 18F-FDG PET/CT in the clinical management of cutaneous melanoma, 4. Describe broadly the best practice in the treatment of cutaneous melanoma, 5. Define the value of systematic review for synthesizing knowledge pertaining to a specific clinical question, and 6. Discuss the utility of 18F FDG PET/CT in the management of early-stage (AJCC 0-IIc) cutaneous melanoma. This is a CME article and provides the equivalent of 2 hours of continuing education that may be applied to your professional development credit system. A 12-question multiple choice quiz follows this reading. Please note that no formalized credit (Category A) is available from CAMRT.