Oligometastases and oligo-recurrence: the new era of cancer therapy.

Recurrence or metastasis of cancer has been considered to occur in the last stage of the patient's life. However, the new notions of oligometastases and oligo-recurrence have been proposed and the paradigm shift in the conceptualization of cancer metastasis or cancer recurrence. Oligometastases is the state in which the patient shows distant relapse in only a limited number of regions. Local therapy such as surgery, radiotherapy and radiofrequency ablation for the relapsed sites could thus improve patient's survival. On the other hand, oligo-recurrence is a notion similar to oligometastases. However, the conditions of oligo-recurrence has a primary site of the cancer controlled, meaning that all gross recurrent or metastatic sites could be treated using local therapy.