P-218 Definitions of oligometastatic pancreatic cancer: A systematic review

Small retrospective series suggest that local consolidative treatment may improve survival in oligometastatic pancreatic ductal adenocarcinoma (PDAC). However, no uniform definition of oligometastatic disease (OMD) in PDAC exists; therefore, hampering meaningful conclusions. This systematic review aims to identify definitions of OMD in PDAC. A systematic literature search using Pubmed, EMBASE, Cochrane CENTRAL, and Web of Science for studies and protocols reporting on definitions or local consolidative treatment of OMD in PDAC was performed. Primary endpoint was the definition of OMD. Level of agreement was categorized as consensus (≥75% agreement between studies), fair agreement (50-74%), and absent/poor agreement ( < 50%). The ROBIN-I tool was used for quality assessment. After screening of 5381 abstracts, 219 studies were assessed in full-text, of which 76 were included in the qualitative synthesis. The majority of studies were retrospective (n=66), while 2 were prospective, and 8 study protocols. Studies investigated mostly liver (n=38, 50.7%), and lung metastases (n=15, 20%). Across studies, less than half (n=32, 42.1%) reported a definition of OMD, while 44 (57.9%) failed to do so. Involvement was limited to a single organ (consensus). Additional criteria for defining OMD were number of lesions (consensus), treatment response (poor agreement), biomarker response (poor agreement), metastatic site (poor agreement), and size (poor agreement). Liver OMD could involve ≤3 lesions (consensus) and synchronous disease (fair agreement), while lung metastases could involve ≤2 lesions and metachronous disease (consensus). The large majority of studies were at a high risk of bias or did not include any control groups; therefore, no meta-analysis on the effect of local consolidative treatment for overall survival was possible. Due to new treatment modalities, clinical interest in oligometastatic pancreatic cancer is increasing. However, definitions of oligometastatic disease varied widely or were non-existent between studies, highlighting an unmet need for a consensus and hampering across-study comparability. The present study is part of structured, multistep process which aims to define an interdisciplinary consensus on oligometastatic pancreatic cancer.