The role of radiotherapy in the treatment of oligometastatic non-small cell lung cancer.

In the recent years, the clinical stage where the cancer has spread beyond the primary site, but has not yet metastasised extensively, and which is known as oligometastatic disease (OMD), has become an object of interest to radiation oncologists. OMD is a kind of an "umbrella term" for a variety of clinical situations. This review focuses on the role of radiotherapy (RT) in the treatment of oligometastatic non-small cell lung cancer (OM-NSCLC). Currently, a wide range of techniques and fractionation regimens are used to treat OM-NSCLC and, unfortunately, it is not yet possible to determine which approach is the most effective. Therefore, more than ever, we should use the concept of risk-adapted RT and consider many factors when choosing the fractionation regimen and total dose applied. For different clinical scenarios, we set different treatment goals and derive different RT techniques and fractionations. Oligoprogression (OP) is a specific type of OMD that is increasingly encountered in clinical situations, probably due to the increased use of targeted therapy and the subsequent acquired resistance of a certain subpopulation of tumour cells. OP is the progression of a limited number of metastases after an initial response to systemic therapy. The rationale for using RT in areas of progression is to overcome tumour resistance in these progressive lesions. A number of trials are currently underway to find the optimal RT techniques for the most appropriate patients at a precise clinical stage.