You will be presented with a collection of medical randomized controlled trial (RCT) reports addressing a shared clinical question -- for instance, the efficacy of a medical intervention on a disease or condition. Given the titles and abstracts of these reports, your task is to generate the conclusion of the systematic review article synthesizing the key findings. Your conclusion should be a few sentences long. In your response, include only the conclusion and no other text. The RCT reports are below.



Title 1:
K-ras mutations and benefit from cetuximab in advanced colorectal cancer.
Abstract 1:
BACKGROUND Treatment with cetuximab , a monoclonal antibody directed against the epidermal growth factor receptor , improves overall and progression-free survival and preserves the quality of life in patients with colorectal cancer that has not responded to chemotherapy . The mutation status of the K-ras gene in the tumor may affect the response to cetuximab and have treatment-independent prognostic value . METHODS We analyzed tumor sample s , obtained from 394 of 572 patients ( 68.9 % ) with colorectal cancer who were r and omly assigned to receive cetuximab plus best supportive care or best supportive care alone  , to look for activating mutations in exon 2 of the K-ras gene . We assessed whether the mutation status of the K-ras gene was associated with survival in the cetuximab and supportive-care groups . RESULTS Of the tumors evaluated for K-ras mutations , 42.3 % had at least one mutation in exon 2 of the gene . The effectiveness of cetuximab was significantly associated with K-ras mutation status ( P=0.01 and P<0.001 for the interaction of K-ras mutation status with overall survival and progression-free survival , respectively ) . In patients with wild-type K-ras tumors , treatment with cetuximab as compared with supportive care alone significantly improved overall survival ( median , 9.5 vs. 4.8 months ; hazard ratio for death , 0.55 ; 95 % confidence interval [ CI ] , 0.41 to 0.74 ; P<0.001 ) and progression-free survival ( median , 3.7 months vs. 1.9 months ; hazard ratio for progression or death , 0.40 ; 95 % CI , 0.30 to 0.54 ; P<0.001 ) . Among patients with mutated K-ras tumors , there was no significant difference between those who were treated with cetuximab and those who received supportive care alone with respect to overall survival ( hazard ratio , 0.98 ; P=0.89 ) or progression-free survival ( hazard ratio , 0.99 ; P=0.96 ) . In the group of patients receiving best supportive care alone , the mutation status of the K-ras gene was not significantly associated with overall survival ( hazard ratio for death , 1.01 ; P=0.97 ) . CONCLUSIONS Patients with a colorectal tumor bearing mutated K-ras did not benefit from cetuximab , whereas patients with a tumor bearing wild-type K-ras did benefit from cetuximab . The mutation status of the K-ras gene had no influence on survival among patients treated with best supportive care alone . ( Clinical Trials.gov number , NCT00079066 .


Title 2:
Cetuximab for the treatment of colorectal cancer.
Abstract 2:
BACKGROUND Cetuximab , an IgG1 chimeric monoclonal antibody against epidermal growth factor receptor ( EGFR ) , has activity against colorectal cancers that express EGFR . METHODS From December 2003 to August 2005 , 572 patients who had colorectal cancer expressing immunohistochemically detectable EGFR and who had been previously treated with a fluoropyrimidine , irinotecan , and oxaliplatin or had contraindications to treatment with these drugs underwent r and omization to an initial dose of 400 mg of cetuximab per square meter of body-surface area followed by a weekly infusion of 250 mg per square meter plus best supportive care  ( 287 patients ) or best supportive care alone  ( 285 patients ) . The primary end point was overall survival . RESULTS In comparison with best supportive care alone , cetuximab treatment was associated with a significant improvement in overall survival ( hazard ratio for death , 0.77 ; 95 % confidence interval [ CI ] , 0.64 to 0.92 ; P=0.005 ) and in progression-free survival ( hazard ratio for disease progression or death , 0.68 ; 95 % CI , 0.57 to 0.80 ; P<0.001 ) . These benefits were robust after adjustment in a multivariable Cox proportional-hazards model . The median overall survival was 6.1 months in the cetuximab group and 4.6 months in the group assigned to supportive care alone . Partial responses occurred in 23 patients ( 8.0 % ) in the cetuximab group but in none in the group assigned to supportive care alone ( P<0.001 ) ; the disease was stable in an additional 31.4 % of patients assigned to cetuximab and in 10.9 % of patients assigned to supportive care alone ( P<0.001 ) . Quality of life was better preserved in the cetuximab group , with less deterioration in physical function and global health status scores ( both P<0.05 ) . Cetuximab treatment was associated with a characteristic rash ; a rash of grade 2 or higher was strongly associated with improved survival ( hazard ratio for death , 0.33 ; 95 % CI , 0.22 to 0.50 ; P<0.001 ) . The incidence of any adverse event of grade 3 or higher was 78.5 % in the cetuximab group and 59.1 % in the group assigned to supportive care alone ( P<0.001 ) . CONCLUSIONS Cetuximab improves overall survival and progression-free survival and preserves quality -of-life measures in patients with colorectal cancer in whom other treatments have failed . ( Clinical Trials.gov number , NCT00079066 [ Clinical Trials.gov ] . )


Title 3:
Phase II trial of cetuximab in patients with refractory colorectal cancer that expresses the epidermal growth factor receptor.
Abstract 3:
PURPOSE To evaluate the antitumor activity and toxicity of single-agent cetuximab in patients with chemotherapy-refractory colorectal cancer whose tumors express the epidermal growth factor receptor . PATIENTS AND METHODS Phase II , open-label clinical trial . Patients were required to have EGFr expression demonstrated on formalin-fixed paraffin-embedded tumor tissue by immunohistochemical staining before study participation . Patients were required to have received irinotecan , either alone or in a combination regimen , and to have demonstrated clinical failure on this regimen before study entry . Cetuximab was administered weekly by intravenous infusion . The first dose of 400 mg/m(2 ) was given during the course of 2 hours . Subsequent weekly treatments were given at a dose of 250 mg/m(2 ) during the course of 1 hour . RESULTS Fifty-seven eligible patients were treated . All were assessable for toxicity and response . The most commonly encountered grade 3 to 4 adverse events , regardless of relationship to study drug , were an acne-like skin rash , predominantly on the face and upper torso ( 86 % with any grade ; 18 % with grade 3 ) , and a composite of asthenia , fatigue , malaise , or lethargy ( 56 % with any grade , 9 % with grade 3 ) . Two patients ( 3.5 % ) experienced grade 3 allergic reactions requiring discontinuation of study treatment . A third patient experienced a grade 3 allergic reaction that resolved , and the patient continued on the study . Neither diarrhea nor neutropenia were dose limiting in any of the 57 patients treated . Five patients ( 9 % ; 95 % CI , 3 % to 19 % ) achieved a partial response . Twenty-one additional patients had stable disease or minor responses . The median survival in these previously treated patients with chemotherapy-refractory colorectal cancer is 6.4 months . CONCLUSION Cetuximab on this once-weekly schedule has modest activity and is well-tolerated as a single agent in patients with chemotherapy-refractory colorectal cancer whose tumors express the epidermal growth factor receptor . Further studies of cetuximab will evaluate the use of cetuximab in conjunction with first-line and adjuvant treatments for this disease
INTERPRETATION KRAS mutation status is a treatment effect modifier for anti-EGFR antibodies in metastatic CRC .