1682P Impact of metastatic site on survival in patients with synchronous metastatic pancreatic adenocarcinoma (PDAC): A national prospective BACAP study

Advanced PDAC carries a dismal prognosis with a 5-year survival rate of 3%. While treated as an even population, previous retrospective studies suggested significant different survival rates for patients (pts) with lung-only metastases (mets) when compared to other pts. This study aims to explore prospectively the difference in survival outcome based on initial site of metastases in synchronous metastatic PDAC. This is a prospective observational study including all adult pts with synchronous metastatic PDAC in BACAP (national Anatomo-Clinical Database on Pancreatic Adenocarcinoma). Data regarding pts demographics, tumor characteristics, and survival outcomes were analyzed. Primary endpoint was overall survival (OS), defined as the time from diagnosis to death or most recent follow-up. Overall, 504 pts were included [52.4% male, mean age 69 years] of which 31 (6.2%), 58 (11.5%), 363 (72%) and 51 (10.1%) pts had lung-only, peritoneal-only, liver-only and multi-site mets at diagnosis, respectively. Most patients (79.2%) received at least one line of chemotherapy. Patients with lung-only mets were older (38.7% were > 75 years old), mostly male (61.3%) and 22.6% received at least 3 lines of chemotherapy (vs 15.5% for other patients). Median OS was significantly different according to mets site (p=0.003) (Table), with a trend towards better PFS when lung-only mets: 6.3 vs 5.4, 4.5 and 2.4 mo when peritoneal-only, liver-only and multi-site mets, respectively (p=0188). Table: 1682PGroupNEvent (%)OS (mo)95% CILung-only2925 (86.2)11.7[9.3; 14.6]Peritoneal-only5849 (84.5)9.2[5.5; 12.9]Liver-only362334 (92.3%)7.2[6.1; 8.1]Multi-site5250 (96.2%)4.1[2.3; 5.0]Total501458 (91.4%)7.2[6.1 ;8.1]p=0.003 Open table in a new tab p=0.003 Pts with lung-only mets represented 6.2% of synchronous metastatic PDAC pts and exhibited improved survival. These results suggest that a subset of pts with synchronous metastatic PDAC could benefit from more aggressive locoregional treatments. Underlying biological mechanisms contributing to survival difference are under investigation.