Is early response by (18)F-2-fluoro-2-deoxy-D-glucose positron emission tomography-computed tomography a predictor of long-term outcome in patients with metastatic colorectal cancer?
BACKGROUND
Identify in advance responder patients to chemotherapy in metastatic colorectal cancer (CRC) would allow prompt interruption of ineffective therapies in non-responder patients. Hence, predictive markers are sought in numerous trials to detect responder patients, including tumor shrinkage measured by imaging methods. Usually, Response Evaluation Criteria in Solid Tumors (RECIST) is used to evaluate tumor response in metastatic CRC, but these criteria are questionable with use of biological agents associated to chemotherapy. Our aim was correlate early metabolic response by (18)F-2-fluoro-2-deoxy-D-glucose positron emission tomography-computed tomography ((18)FDG-PET-CT) with long-term outcome in metastatic CRC in first-line therapy.


METHODS
We prospectively evaluated 36 patients with metastatic CRC in first-line treatment with 5-fluorouracil, leucovorin (folinic acid), oxaliplatin (FOLFOX) or 5-fluorouracil, leucovorin (folinic acid), irinotecan (FOLFIRI) associated with cetuximab or bevacizumab. (18)FDG-PET-CT was performed at baseline and after two cycles of chemotherapy. The early metabolic response [standardized uptake value (SUV)] was measured to identify responder and non-responder patients and correlated with overall survival (OS) and progression-free survival (PFS).


RESULTS
Median age was 58.5 years (range, 41-74 years). PFS was 15.5 months for responder and 13.3 months for non-responder (P=0.42), OS was 55.7 months for responder and not reached for non-responder. There was no correlation between delta-SUV and clinical and pathological variables analyzed. In the subgroup of patients who did not undergo resection of metastasis (45%), PFS was higher for responders (15.3×6.8 months, P=0.02).


CONCLUSIONS
According to our findings, early response by (18)FDG-PET-CT was not a predictor of long-term outcome for patients with metastatic CRC treated in the first-line chemotherapy with a monoclonal antibody.
1 Department of Medical Oncology, 2 Department of Radiology and Nuclear Medicine, AC Camargo Cancer Center, São Paulo, SP, Brazil.
Maria Nirvana da Cruz
MN
Formiga
1 Department of Medical Oncology, 2 Department of Radiology and Nuclear Medicine, AC Camargo Cancer Center, São Paulo, SP, Brazil.
Marcello Ferretti
MF
Fanelli
1 Department of Medical Oncology, 2 Department of Radiology and Nuclear Medicine, AC Camargo Cancer Center, São Paulo, SP, Brazil.
Aldo Lourenço Abadde
AL
Dettino
1 Department of Medical Oncology, 2 Department of Radiology and Nuclear Medicine, AC Camargo Cancer Center, São Paulo, SP, Brazil.
Ulisses Ribaldo
UR
Nicolau
1 Department of Medical Oncology, 2 Department of Radiology and Nuclear Medicine, AC Camargo Cancer Center, São Paulo, SP, Brazil.
Marcelo
M
Cavicchioli
1 Department of Medical Oncology, 2 Department of Radiology and Nuclear Medicine, AC Camargo Cancer Center, São Paulo, SP, Brazil.
Eduardo Nóbrega Pereira
EN
Lima
1 Department of Medical Oncology, 2 Department of Radiology and Nuclear Medicine, AC Camargo Cancer Center, São Paulo, SP, Brazil.
Celso Abdon Lopes
CA
de Mello
Metabolic response; colorectal cancer (CRC); positron emission tomography