O2–093COMPARISON BETWEEN PRIMARY TUMOR RESECTION AND PRIMARY CHEMOTHERAPY FOR PATIENTS WITH UNRESECTABLE COLORECTAL CANCER

Purpose: In the absence of urgent bleeding or obstruction, the role of prophylactic resection of asymptomatic primary colorectal tumor is controversial. We inspected a hypothesis that the number of metastatic site helps the decision on the precedence between surgery and chemotherapy. Patients and Methods: We surveyed the institutional database from 2005 through 2012, and identified 82 consecutive colorectal cancer patients with unresectable synchronous metastases. We retrospectively stratified patients according to the numberof metastatic site, and then compared patients’ characteristics, treatment regimen, and survival outcome. Results: Median age of 82 patients was 63 years, and median follow-up was 16.5 months. 36 patients underwent surgery objected to resect primary tumor and received subsequent chemotherapy (surgery group). 46 received up-front chemotherapy without surgery (chemotherapy group). Asthe first- line chemotherapy, oxaliplatin based regimen were used in 27 patients (75 %) on the surgery group, and in 42 (91 %) on the chemotherapy group. Bevacizumab was used in 13 (36 %), and in 33 (71 %), respectively. Median OS seemed slightly better for the surgery group compared to the chemotherapy group, with 21.9 vs. 18.9 months (P= 0.21). Especiallyamong cases in which patients had onlyone metastatic site, there seemed to be an obvious survival benefit for the surgery group (26.9 vs. 20.0 months, P= 0.11). Among cases with two metastatic sites, OS were shown equally in both groups (19.9 vs. 18.9 months, P= 0.56). With three or more metastatic sites, OS of the surgery group seemed worse and insufficient (8.0 vs. 13.6 months, P= 0.15). In the chemotherapy group, 7 patients (15 %) required emergent surgeryorendoscopic stenting. Conclusion: Surgery for primary tumor could be beneficial for specific population who has one metastatic site. Most of patients with advanced metastases (i.e. mets number >= 2) could be successfully and safely managed by primary chemotherapy.