Background: It is controversial that the primary tumor must be removed prior chemotherapy in cStage4 colorectal cancer, because some cases prognostic factor were metastatic sites. We report cases of cStage4 colorectal cancer which were underwent intrensive chemotherapy prior the primary tumor resection. Methods: 190 cases of metastatic colorectal cancer were treated by L-OHP based chemotherapy plus bevacizumab/cetuximab/panitumumab in September 2007 to June 2012. 56 cases were treated by intensive chemotherapy prior primary tumor resection, and 44 cases were underwent surgical resection of primary tumor after evaluation of chemotherapy response. Results: 38/10/8 cases were treated by bevacizumab/cetuximab/panitumumab with L-OHP combined therapy as intensive treatment. 30 patient with obstructed primary lesion were underwent stoma surgery (53.6%). Evaluable lesions except primary lesion were liver (50.0%), lung (12.5%), LNs (33.9%). Response rate of chemotherapy were 67.9% (PR/NC/PD: 38/14/4), and 44 cases were performed resection of primary lesion in PR and SD cases. Pathological G2 and G3 response in resected primary lesion were 18.4% (G1a/G1b/G2/G3:17/18/8/2). A GI perforation and bowel obstruction in chemotherapy and 3 cases of anastomotic leakage and 6 cases of SSI in perioperable period were observed respectively. Conclusions: It is seemed to contribute improvement of QOL and local control that start with systemic chemotherapy prior primary lesion resection, therefore some cStage4 cases were difficult to R0 resection also primary lesion and systemic chemotherapy could be reduced symptom with metastatic sites. Only 18.4% of the resected primary tumor were G2/3 pathological response by systemic chemotherapy, on the other hand preoperative chemo-radiation in rectal cancer accomplished 67.3% of G2/3 pathological response (in house data). The end-point of therapy in stage 4 colorectal cancer patient are QOL and prolong survival, and should be selected treatments depending on the patient condition.