Population-based colorectal cancer screening: comparison of two fecal occult blood test.
BACKGROUND
The aim of screening for colorectal cancer is to improve prognosis by the detection of cancer at its early stages. In order to inform the decision on the specific test to be used in the population-based program in the Basque Autonomous Region (Spain), we compared two immunochemical fecal occult blood quantitative tests (I-FOBT).


METHODS
Residents of selected study areas, aged 50-69 years, were invited to participate in the screening. Two tests based on latex agglutination (OC-Sensor and FOB Gold) were randomly assigned to different study areas. A colonoscopy was offered to patients with a positive test result. The cut-off point used to classify a result as positive, according to manufacturer's recommendations, was 100 ng/ml for both tests.


RESULTS
The invited population included 37,999 individuals. Participation rates were 61.8% (n = 11,162) for OC-Sensor and 59.1% (n = 11,786) for FOB Gold (p = 0.008). Positive rate for OC-Sensor was 6.6% (n = 737) and 8.5% (n = 1,002) for FOB Gold (p < 0.0001). Error rates were higher for FOB gold (2.3%) than for OC-Sensor (0.2%; p < 0.0001). Predictive positive value (PPV) for total malignant and premalignant lesions was 62.4% for OC-Sensor and 58.9% for FOB Gold (p = 0.137), respectively.


CONCLUSIONS
OC-Sensor test appears to be superior for I-FOBT-based colorectal cancer screening, given its acceptance, ease of use, associated small number of errors and its screening accuracy. FOB Gold on the other hand, has higher rate of positive values, with more colonoscopies performed, it shows higher detection incidence rates, but involves more false positives.
Clinical Epidemiology Unit, Cruces University Hospital, Basque Health Service Barakaldo, Bizkaia, Spain.
Miren B
MB
Zubero
Clinical Epidemiology Unit, Cruces University Hospital, Basque Health Service Barakaldo, Bizkaia, Spain ; BioCruces Health Research Institute Bizkaia, Spain.
Eunate
E
Arana-Arri
Clinical Epidemiology Unit, Cruces University Hospital, Basque Health Service Barakaldo, Bizkaia, Spain ; BioCruces Health Research Institute Bizkaia, Spain ; Biomedical Research Center Network for Epidemiology and Public Health Bizkaia, Spain.
José I
JI
Pijoan
Colorectal Cancer Screening Programme Coordinating Centre, Basque Health Service Bizkaia, Spain.
Isabel
I
Portillo
Colorectal Cancer Screening Programme Coordinating Centre, Basque Health Service Bizkaia, Spain.
Isabel
I
Idigoras
Clinical Biochemistry Service, Cruces University Hospital, Basque Health Service Barakaldo, Bizkaia, Spain.
Antonio
A
López-Urrutia
Clinical Biochemistry Service, Donostia University Hospital, Basque Health Service Donostia, Gipuzkoa, Spain.
Ana
A
Samper
Digestive Department, Donostia University Hospital, Basque Health Service Donostia, Gipuzkoa, Spain.
Begoña
B
Uranga
Clinical Biochemistry Service, Araba University Hospital, Basque Health Service Gasteiz, Araba, Spain.
Carmen
C
Rodríguez
Digestive Department, Donostia University Hospital, Basque Health Service Donostia, Gipuzkoa, Spain ; Biodonostia Research Institute Donostia, Spain.
Luis
L
Bujanda
colorectal cancer; health impact assessment; health outcomes research; immunochemical fecal occult blood test; population screening