What is the definition of oligoprogression in oncology?

Definition of Oligoprogression in Oncology

Oligoprogression is defined as progression of a limited number of metastatic foci (typically up to 5 lesions) while all other metastatic sites remain controlled under ongoing systemic therapy. 1

Key Characteristics of Oligoprogression

• Oligoprogression occurs in patients already receiving systemic therapy (such as targeted therapies, immunotherapies, or chemotherapy) who develop limited progression while most disease sites remain controlled 1, 2
• The upper limit to the number of metastases is not universally defined, but most clinical trials and guidelines include up to 5 progressive lesions 1, 2
• Oligoprogression differs from:
  • Oligometastatic disease (initial presentation with limited metastases) 1
  • Oligopersistent disease (induced state where polymetastatic disease responds to treatment and decreases to fewer than 5 sites of active disease) 2

Clinical Significance and Management

• Oligoprogression represents a unique clinical scenario where limited sites of disease develop resistance to ongoing systemic therapy while the majority of disease remains controlled 3
• Management options for oligoprogression include:
  • Local ablative therapy to the progressing sites while continuing current systemic therapy 1
  • Switching systemic therapy 4
  • Combination approaches 1

Local Ablative Therapy Options

• Stereotactic body radiotherapy (SBRT)/stereotactic ablative radiotherapy (SABR) 1, 4
• Surgical resection (metastasectomy) 1
• Image-guided thermal ablation (IGTA) techniques 1
• Stereotactic radiosurgery (SRS) for brain lesions 1

Evidence Supporting Local Therapy for Oligoprogression

• In non-small cell lung cancer (NSCLC), local therapy for oligoprogressive lesions while continuing effective systemic therapy has shown promising results:

  • For patients with EGFR mutations, local therapy to oligoprogressive sites can allow continued use of EGFR TKIs 1
  • For ROS1-positive NSCLC with oligoprogression, local therapy can be considered while continuing TKI therapy 1
  • A prospective study of SABR for oligoprogressive metastases in patients on TKI therapy showed 93% local control and 92% overall survival at 1 year 1

• In renal cell carcinoma (RCC), local therapy for oligoprogressive disease has been evaluated:

  • A prospective single-arm multicenter study showed SABR to oligoprogressive metastases extended progression-free survival by 9.3 months and delayed switching systemic therapy by 12.6 months 1

Clinical Implications

• The concept of oligoprogression has important treatment implications:
  • It may allow continuation of otherwise effective systemic therapy by addressing resistant clones locally 5
  • It can potentially delay the need to switch to next-line systemic therapy, which may have different toxicity profiles or reduced efficacy 1, 4
  • It may improve quality of life by maintaining disease control with the current well-tolerated therapy 3

Pitfalls and Caveats

• Patient selection is critical - not all patients with limited progression will benefit from local therapy 4, 2
• Comprehensive imaging (including PET-CT when appropriate) should be used to accurately identify all sites of disease 1
• The optimal timing of local therapy and whether to continue or switch systemic therapy remains controversial 4
• Most evidence supporting local therapy for oligoprogression is retrospective or from small prospective studies; randomized controlled trials are ongoing 3, 5
• Performance status should be considered when deciding on local therapy approaches, as ECOG PS of 2 has been associated with poorer outcomes 4

Future Directions

• Ongoing prospective trials are evaluating the role of local therapy in oligoprogressive disease across various cancer types 3
• Biomarkers to identify patients most likely to benefit from local therapy for oligoprogression are needed 2
• The optimal integration of local therapy with novel systemic agents requires further investigation 5