title: Colorectal cancer in a second round after a negative faecal immunochemical test.
abstract: OBJECTIVE
  The faecal immunochemical test is one of the tests recommended by scientific societies for colorectal cancer (CRC) screening in average-risk populations. Our aim was to evaluate the characteristics of CRC detected in a second round of screening after negative results in a first round.
  
  
  METHODS
  We studied patients in whom CRC was detected in a screening programme. This programme included asymptomatic individuals between 50 and 69 years old and offered tests every 2 years. A total of 363,792 individuals were invited to participate in the first round of faecal immunochemical test screening and 100,135 individuals in the second round after a first negative result. The screening strategy consisted of faecal testing of a single sample using an automated semiquantitative kit, with a cut-off of 20 μg haemoglobin (Hb)/g faeces.
  
  
  RESULTS
  The rate of positive results was 6.9% (16,467/238,647) in the first round and 4.8% (3359/69,193) in the second round (P < 0.0005). Overall, 860 (0.36%) cases of CRC were detected in the first round and 100 (0.14%) in the second round (P < 0.005). The location of the cancer was proximal in 12.5 and 24% of cases detected in the first and second rounds, respectively (P = 0.008). Hb concentrations were higher in the first round (211 vs. 109 μg Hb/g faeces in the second round; P = 0.002). Multivariate analysis confirmed that, in the second round, CRC diagnosed was more often proximal (hazard ratio vs. first round, 2.4; 95% confidence interval, 1.3-4.4; P = 0.003) and the concentration of Hb/g faeces was lower (hazard ratio vs. first round, 2.1; 95% confidence interval, 1.3-3.5; P = 0.003).
  
  
  CONCLUSIONS
  The CRC detection rate is lower in the second round of screening. Further, in the second round, CRC detected is more often in a proximal location and Hb concentrations are lower.
authors: aDepartment of Gastroenterology, Hospital Donostia, Instituto Biodonostia, Centro de Investigación Biomédica en Red en Enfermedades Hepáticas y Digestivas (CIBERehd), Universidad del País Vasco (UPV/EHU) bHospital Universitario Donostia, Red de Investigación en Servicios de Salud en Enfermedades Crónicas (REDISSEC), San Sebastián cDepartment of Gastroenterology, Hospital Clínic, Centro de Investigación Biomédica en Red en Enfermedades Hepáticas y Digestivas (CIBERehd), IDIBAPS, University of Barcelona, Barcelona dServicio de Aparato Digestivo, Complexo Hospitalario Universitario de Ourense, Ourense eHospital Universitario de Cruces, Baracaldo fPrograma de Cribado de Cáncer Colorrectal, Servicio Vasco de Salud, País Vasco, Spain.
authors: Luis
authors: L
authors: Bujanda
authors: Cristina
authors: C
authors: Sarasqueta
authors: Antoni
authors: A
authors: Castells
authors: María
authors: M
authors: Pellisé
authors: Joaquín
authors: J
authors: Cubiella
authors: Inés
authors: I
authors: Gil
authors: Angel
authors: A
authors: Cosme
authors: Eunate
authors: E
authors: Arana-Arri
authors: Izaskun
authors: I
authors: Mar
authors: Isabel
authors: I
authors: Idigoras
authors: Isabel
authors: I
authors: Portillo
mesh_terms: D000368:Aged; D015179:Colorectal Neoplasms / Q000175:diagnosis*; D055088:Early Detection of Cancer; D005243:Feces / Q000737:chemistry*; D005260:Female; D006801:Humans; D007120:Immunochemistry; D008297:Male; D008403:Mass Screening / Q000379:methods; D008875:Middle Aged; D009780:Occult Blood; D011237:Predictive Value of Tests; D012680:Sensitivity and Specificity; D013030:Spain; D013997:Time Factors