Abstract
407
Background: Many studies have associated a R0 resection to have significantly improved survival compared with a R1 resection in PAC. Patients (pts) who undergo NACRT often go to surgery 4-8 weeks after the end of therapy, before the effects of NACRT can be fully manifested. The goal of this study is to evaluate if a positive SM (+SM) after NACRT has the same poor prognosis as a +SM after upfront surgery. Methods: After IRB approval, we retrospectively reviewed all cases of surgically resected PAC at a single institution from Dec 1996 to Jan 2014. Pts were stratified by receipt of NACRT as well as by SM status. We excluded pts treated with palliative intent, metastatic disease at presentation, death within 90 days of surgery, and biliary or ampullary tumors. The primary endpoint was overall survival (OS). We assessed the relationship between pt and tumor variables with treatment/margin combination using Chi-squared tests. OS was examined using Kaplan-Meier curves, and we tested association with treatment/margin using log-rank tests. Results: A total of 213 pts met inclusion criteria; 111 received upfront surgery (group I) with 94 (85%) receiving adjuvant chemotherapy or CRT and 102 received NACRT (group II) with either concurrent 5-fluorouracil (n=18) or gemcitabine (n=84). There were 31 pts with +SM in group I and 29 pts in group II. Pt demographics were balanced. There was more vessel involvement in group II (81%) at diagnosis than group I (11%) (p<0.01) with a trend towards improved OS in group II vs group I (p=0.09). Pathological evaluation revealed more PNI (61% vs 42%, p<0.01) and more lymph node positivity (71% vs 33%, p<0.01) in group I vs group II, respectively. Median OS for group I SM+/SM- and group II SM+/SM- were 15/25 months and 26/32 months respectively. OS is significantly improved with a negative SM (-SM) compared with a +SM (p<0.01). If the SM is positive, pts in group II had improved OS compared with group I (p=0.02). OS was not significantly different for group II +SM vs group I –SM (p=0.34). Conclusions: The negative impact of a +SM on survival is partially mitigated by NACRT. This data further supports the use of NACRT, although it is limited by its retrospective nature and small sample size.
