Introduction to Melanoma
Skin imaging is crucial for the early detection of melanoma. There are many different techniques that are in use in the clinic, such as dermoscopy, confocal laser scanning microscopy, ultrasound, PET scan, and MRI. Following diagnosis, accurate disease staging is appropriate for treatment planning, and the detection of distant metastases is very important. In high-risk patients, CT or whole-body PET/CT scan may lead to an earlier diagnosis of regional or systemic relapses. However, an impact of radiological exams upon survival has not been demonstrated. The spread of imaging techniques and the cooperation of many specialists have led to the selection of the most appropriate therapies for patients with melanoma.
KeywordsMelanoma Imaging Brain metastases PET/CT scan MRI Follow-up
Cutaneous melanoma is the most widely metastasizing neoplastic disease, with the least predictable pattern of spread. The incidence of melanoma worldwide has increased, by average of 2.5% per year, a rate higher than any other malignancy. In the USA, the lifetime risk for developing melanoma has increased from 1:1500 in 1930 to 1:75 in 2000. The current lifetime risk for developing the disease in Australia is 1 in 25 . Melanoma confined to the epidermis is effectively curable, and thin lesions carry a 98% 5-year survival rate. However, patients with primary tumors of >4 mm thickness have a <50% survival rate. Nearly, 50% of patients are at risk for recurrence, which is most common in the years immediately after diagnosis . An estimated 20% of all the first recurrences occur locally, 50% occur in the regional lymph nodes, and 30% arise at distant sites . The median survival for disseminated disease is now 25 months with the use of BRAF and MEK inhibitors and /or with immunotherapy. The 5-year survival for the metastatic disease ranges between 35%–50%.
Despite the known benefits of early detection of recurrence, no evidence-based surveillance guidelines exist, and clinical patterns vary widely. Thus, it is important to define optimal follow-up strategies, including the most effective imaging techniques and evaluation intervals, assuming that early diagnosis, detection of metastases, and prediction of response are beneficial and crucial for the patients.
Finally, current drugs provide long-term survival for a subset of patients, but most progress and die. We need better treatment to raise the bar. We need better biomarkers and imaging techniques to predict the outcomes of the patients. The goal should not simply be to improved overall survival, but improved long-term control, preferably off therapy, and not just in melanoma but across cancer.