title: CT versus FDG-PET/CT response evaluation in patients with metastatic colorectal cancer treated with irinotecan and cetuximab.
abstract: We compared morphologic computed tomography (CT)-based to metabolic fluoro-deoxy-glucose (FDG) positron emission tomography (PET)/CT-based response evaluation in patients with metastatic colorectal cancer and correlated the findings with survival and KRAS status. From 2006 to 2009, patients were included in a phase II trial and treated with cetuximab and irinotecan every second week. They underwent FDG-PET/CT examination at baseline and after every fourth treatment cycle. Response evaluation was performed prospectively according to Response Evaluation Criteria in Solid Tumors (RECIST 1.0) and retrospectively according to Positron Emission Tomography Response Criteria in Solid Tumors (PERCIST). Best overall responses were registered. Sixty-one patients were eligible for response evaluation. Partial response (PR) rate was 18%, stable disease (SD) rate 64%, and progressive disease (PD) rate 18%. Partial metabolic response (PMR) rate was 56%, stable metabolic disease rate 33%, and progressive metabolic disease (PMD) rate 11%. Response agreement was poor, κ-coefficient 0.19. Hazard ratio for overall survival for responders (PR/PMR) versus nonresponders (PD/PMD) was higher for CT- than for FDG-PET/CT evaluation. Within patients with KRAS mutations, none had PR but 44% had PMR. In conclusion, morphologic and metabolic response agreement was poor primarily because a large part of the patients shifted from SD with CT evaluation to PMR when evaluated with FDG-PET/CT. Furthermore, a larger fraction of the patients with KRAS mutations had a metabolic treatment response.
authors.affiliation: Department of Oncology, Copenhagen University Hospital Herlev, Herlev, Denmark.
authors.forename: Kristin
authors.initials: K
authors.lastname: Skougaard
authors.forename: Helle Hjorth
authors.initials: HH
authors.lastname: Johannesen
authors.forename: Dorte
authors.initials: D
authors.lastname: Nielsen
authors.forename: Jakob Vasehus
authors.initials: JV
authors.lastname: Schou
authors.forename: Benny Vittrup
authors.initials: BV
authors.lastname: Jensen
authors.forename: Estrid V S
authors.initials: EV
authors.lastname: Høgdall
authors.forename: Helle Westergren
authors.initials: HW
authors.lastname: Hendel
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D061067:Antibodies, Monoclonal, Humanized / Q000008:administration & dosage; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use*; D002166:Camptothecin / Q000008:administration & dosage / Q000031:analogs & derivatives; D000068818:Cetuximab; D015179:Colorectal Neoplasms / Q000175:diagnosis* / Q000188:drug therapy* / Q000235:genetics / Q000401:mortality; D018450:Disease Progression; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D000077146:Irinotecan; D008297:Male; D008875:Middle Aged; D009362:Neoplasm Metastasis; D049268:Positron-Emission Tomography; D011518:Proto-Oncogene Proteins / Q000235:genetics; D016283:Proto-Oncogene Proteins p21(ras); D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome; D018631:ras Proteins / Q000235:genetics
chemical_list: D061067:Antibodies, Monoclonal, Humanized; C117307:KRAS protein, human; D011518:Proto-Oncogene Proteins; D019788:Fluorodeoxyglucose F18; D000077146:Irinotecan; D016283:Proto-Oncogene Proteins p21(ras); D018631:ras Proteins; D000068818:Cetuximab; D002166:Camptothecin
keywords: Colorectal cancer; KRAS; PERCIST; PET/CT; RECIST; response evaluation; survival