Stereotactic body radiation therapy for oligoprogression of metastatic disease from gastrointestinal cancers: A novel approach to extend chemotherapy efficacy.

Chemotherapy and targeted therapies are effective palliative options for numerous unresectable or metastatic cancers. However, treatment resistance inevitably develops leading to mortality. In a subset of patients, systemic therapy appears to control the majority of tumors leaving 5 or less to progress, a phenomenon described as oligoprogression.