Hassan, Mohamed A.

452 Background: Surgical resection is the only curative treatment for patients with gallbladder cancer, despite surgical advances many patients ultimately develop recurrent disease. Management of resected gallbladder cancer mostly relies on single-arm trials and retrospective observations. The purpose of our study is to assess the role of adjuvant therapy in stage I-III gallbladder cancer patients who have undergone surgical resection. Methods: Clinical data were collected on 251 patients who underwent surgical resection for stage I-III gallbladder cancer and presented to Mayo clinic from January 2000-December 2015. Patients were then classified into adjuvant treatment group and surveillance only group. Overall survival and recurrence were compared between the two groups. Results: 78 (31.1%) patients received adjuvant therapy while 173 patients were observed only. Patients who received adjuvant tended to be younger (63.0[SD 11] vs 66.2 [SD 13.1]), have higher stage, and underwent extended surgery. Most patients received chemoradiotherapy (55) with 5-Fluorouracil (67.3%) and capecitabine (25.5%) as radiosensitizing agents. 21 patients received additional adjuvant chemotherapy. 27% of patients received chemotherapy as the sole adjuvant treatment. The most common chemo regimens included gemcitabine (52.3%) and gemcitabine plus cisplatin combination (23.8%). On multivariate analysis patients > 65 years(HR 1.53 [1.07-2.19], p = 0.02), males (HR 1.7 [1.2-2.4], p = 0.003), positive margins (2.77 [1.69-4.38], p < 0.01), and stage III (HR 1.91 [1.35-2.70], p < 0.01) had worse overall survival. Patients who underwent extended radical resection (HR 0.73 [0.51-1.05], p = 0.09) had better overall survival. Adjuvant therapy had no statistical significant effect on overall survival (HR 1.10 [0.75-1.59], p = 0.63 or disease free survival (HR 1.05 [0.69-1.59], p = 0.81) on overall population. However, in stage IIIB, patients receiving adjuvant therapy had better overall survival (HR 0.51 [0.25-1.01], p = 0.05) and disease free survival (HR 0.45 [0.19-1.09], p = 0.06). Conclusions: In our study, adjuvant treatment, especially chemoradiation therapy, was only beneficial in patients with stage IIIb gallbladder cancer patients.

450 Background: The standard treatment for patients with gallbladder cancer is a combination of gemcitabine and cisplatin based on ABC-02 trial. However, there are no guidelines regarding treatment after first-line therapy. We retrospectively analyzed the efficacy and overall survival of different second-line regimens. Methods: We identified 203 patients with advanced gallbladder cancer who received palliative treatment between January 2000 and December 2015 at Mayo Clinic, Rochester. RECIST criteria was used to assess response. Results: 68 patients received second-line chemotherapy. Median age was 63 years (range: 32-86) and majority were males (60.6%). The median time from the diagnosis to the start of the second line chemotherapy was 8 (1-120) months. The most common used second-line chemotherapy were FOLFOX (14), gemcitabine alone (10), single agent fluoropyrimidine (11), gemcitabine with capecitabine (5), and capecitabine with oxaliplatin (4). There were 30 patients that received 5-fluorouracil based regimens, 20 patients received gemcitabine-based regimen, 3 patients received taxane-based regimen, and 15 patients received other types of chemotherapy. Median progression free survival and overall survival was 2.1 (1.8-2.7) and 16.7 (13.2-21.3) months respectively. There were 10 (52%), 11 (37%), 2 (67%), 5 (33%) with partial response and stable disease in 5-fluorouracil-based, gemcitabine-based, taxane-based, and others, respectively. There were no difference in PFS, with median PFS of 2.5, 2.0, 2.8 and 2.3 months, respectively (p=0.43). The overall survival were 15.7 (8.9-40.2), 15.0 (10.7-21.3), 40.3 (22.0-47.0), and 20.4 (9.2-30.7) months, respectively (p=0.83). There were 27 patients that received single agent chemotherapy and 41 patients that received combined regimen. There were 17 (42%) patients and 13 (48%) patients with partial response or stable disease in single and combined regimen. There were no differences in progression free survival and overall survival between single and multi agent chemotherapy. Conclusions: In this largest single institution study, second-line chemotherapy regimens for gallbladder cancer provided benefit in select patients and there is an urgent need to develop more active therapeutic regimens.