3428 - Utility of Screening for Oligometastatic Disease: A Systematic Review

Purpose/Objective(s): Oligometastatic disease (OMD) is increasingly being managed with radical intent, with goals of improving local control and progression-free survival. Lesions detected early – before symptom onset – are more likely to be amenable to locally ablative therapy (LAT). No guidelines define which asymptomatic cancer populations would benefit from screening for OMD, potentially leading to unnecessary test-related complications, poor resource utilization, and delays in treatment initiation awaiting results which will not alter management. We aimed to identify whether screening versus investigation after symptom onset increases the detection rate of oligo- versus polymetastatic disease (PMD).

Materials/Methods: We systematically reviewed literature comparing the number of metastases identified in patients undergoing standardized screening or staging with those who did not undergo screening. The primary endpoint was number of patients with OMD potentially amenable to LAT. A literature search of EMBASE, MEDLINE, and Cochrane Library of English publications including keywords “screening” or “diagnostic” and “metastasis” (2000 to 2024) was supplemented by searching reference lists. Studies were excluded if screening was for regional disease or if symptom status was unknown. Many did not report specific number of metastases identified, so we also included studies which reported metastases identified via screening, even if OMD versus PMD could not be discerned.

Results: Of 4093 citations initially identified, 45 were eligible for inclusion (14/45 prospective) including 32801 patients. In 45/45, screening modalities were radiologic; 3/45 also included biochemical modalities. 10 studies on screening for brain metastases in non-small cell lung cancer identified brain metastasis in 3-20% of patients depending on imaging modality. Of those, about 50% were amenable to LAT. In non-metastatic castrate-resistant prostate cancer (N=3 studies), PSMA PET-CT detects metastases in nearly 66% of patients, with two-thirds being candidates for LAT. All 3 studies on uveal melanoma identified disease confined to the liver, of which approximately 40% were amenable to LAT. In colorectal cancer (N=2 studies), screening identified metastases in 15%, of whom 65% were LAT candidates. There is insufficient evidence to support screening in breast, sarcoma, melanoma, gastric, or pancreatic cancers at present.

Conclusion: Evidence-based recommendations are limited by data heterogeneity and a lack of prospective studies. While screening appears to detect asymptomatic OMD potentially amenable to LAT, further research is needed to determine the specific populations in which screening impacts clinical outcomes and is cost-effective.