Oligometastatic skin melanoma: molecular-genetic characteristics and the effectiveness of surgical intervention

“Oligometastatic” represents a so-called transitional stage between localized and disseminated process. The process itself is characterized by the presence of a primary tumor and a limited number of distant solitary metastases. The disease progression in oligometastatic cancer is slower compared to the massive dissemination, and the prognosis is more favorable. Oligometastatic process has been described in many malignancies, including melanoma, lung cancer, breast cancer, and others. This article focuses on oligometastatic melanoma and the role of surgical treatment in this scenario of disease progression. One of the early theories of oligometastatic cancer was proposed in 1995. According to this theory, malignant neoplasms first develop as a single focus of initial (primary) tumor, followed by solitary involvement of distant tissues and organs (oligometastatic phase), and later progress to full dissemination and massive spread throughout the body. Weak points of this theory became evident as clinical practice showed that in some patients, the oligometastatic form of the disease did not progress to systemic dissemination, indicating that oligometastasis in this patient cohort was not an intermediate stage of disease development, but rather a separate form of tumor progression. Another theory, encompassing the concept of oligometastasis, suggests that tumor malignancy is inherently a disseminated process, and the primary tumor and primary (solitary) oligometastases are simply the first detectable foci large enough to be visualized by diagnostic methods. However, similar to the previous theory, this approach fails to explain prolonged periods (or even constant presence) of oligometastatic disease in specific patient cohorts. The modern understanding of the cause of oligometastasis is complex and consists of several statements. It is based on diverse molecular and genetic characteristics of malignant neoplasms, even within the same nosological entity and histological subtype. For metastatic process to take place, tumor cells must possess certain characteristics such as loss of adhesion, increased invasiveness, migratory capacity, and the ability to adapt and thrive in new microenvironments. This article emphasizes the importance of surgical treatment in cases of oligometastatic disease and provides information on the current understanding of the mechanisms underlying this process.