BackgroundThe　benefit　of　adjuvant　therapy　(AT)　after　curative　resection　of　distal　cholangiocarcinoma　(DCC)　remains　unclear.　The　objective　of　the　current　study　was　to　investigate　the　impact　of　AT　on　long-term　survival　of　patients　who　underwent　curative-intent　resection　for　DCC.　MethodsPatients　who　underwent　curative-intent　resection　for　DCC　between　2000　and　2020　were　identified　from　a　multi-institutional　database.　The　primary　outcomes　included　overall　(OS)　and　recurrence-free　survival　(RFS).　ResultsAmong　245　patients,　150　(61.2%)　patients　received　AT　(chemotherapy　alone:　n　=　43;　chemo-　and　radiotherapy:　n　=　107)　after　surgical　resection,　whereas　95　(38.8%)　patients　underwent　surgery　only.　Patients　who　received　AT　were　younger,　and　more　likely　to　have　an　advanced　tumor　with　the　presence　of　perineural　invasion　(PNI),　lymph　node　metastasis　(LNM),　lymph-vascular　invasion,　and　higher　T　categories　(all　p　＜　0.05).　Overall,　there　was　no　difference　in　OS　(median,　surgery　+　AT　25.5　vs.　surgery　alone　24.5　months,　p　=　0.27)　or　RFS　(median,　surgery　+　AT　15.8　vs.　surgery　alone　18.9　months,　p　=　0.24)　among　patients　who　did　versus　did　not　receive　AT.　In　contrast,　AT　was　associated　with　improved　long-term　survival　among　patients　with　PNI　(median　OS,　surgery　+　AT　25.9　vs.　surgery　alone　17.8　months,　p　=　0.03;　median　RFS,　surgery　+　AT　15.9　vs.　surgery　alone　11.9　months,　p　=　0.04)　and　LNM　(median,　surgery　+　AT　20.0　vs.　surgery　alone　17.8　months,　p　=　0.03),　but　not　among　patients　with　no　PNI　or　LNM　(all　p　＞　0.1).　ConclusionsAT　was　commonly　utilized　among　patients　with　DCC.　Patients　with　more　advanced　disease,　including　the　presence　of　PNI　or　LNM,　benefited　the　most　from　AT　with　improved　long-term　outcomes　among　this　subset　of　patients.