Estudio prospectivo acerca de la precisión diagn´óstica del test inmunológico de sangre oculta en materia fecal en una única ronda para la realización de pesquisa del cáncer colorrectal en pacientes de riesgo promedio en la Argentina

BACKGROUND: Colorectal cancer (CRC) is the second leading cause of cancer death in Argentina. Due to its high prevalence, it is of paramount importance to standardize a screening program for prevention and early detection of this disease. The diagnostic precision of the fecal immunochemical test (FIT) for CRC detection in the average-risk population has shown to be adequate according to the international literature, however, there is no local information. OBJECTIVE: To evaluate the diagnostic precision of a single round of FIT for CRC screening in average-risk subjects. DESIGN: Diagnostic precision prospective study MATERIAL AND METHOD: average risk patients who consulted to perform a screening colonoscopy between June 1, 2014 and December 31, 2017 at the Hospital Aleman in Buenos Aires were included. Subjects with increased CRC risk were excluded. Participants were assigned to firstly perform a FIT and later the colonoscopy.  Endoscopists were blinded to the FIT results. The diagnostic precision of the FIT to detect advanced neoplastic lesions (ANL) was evaluated by calculating the sensitivity (S), specificity (E), positive (PPV) and negative predictive value (NPV), positive likelihood ratio (LR+) and negative likelihood ratio (LR­-). The accuracy to detect low-risk adenomas, serrated polyps and CRC was also evaluated. RESULTS: A total of 300 patients were included; 273 (91%) delivered the stool sample to perform the FIT and completed the colonoscopy. Patients mean age was 56.9 years (40-85) and 54% were men. Of all patients who performed both studies, 53 patients (19%) had at least one low-risk adenoma, 18 patients (6.6%) at least one sessile serrated adenoma and 21 patients (7.7%) at least one advanced neoplastic lesion (ANL). Only 4 patients (1.5%) harbored a CRC. In regard to the diagnostic precision of a single round of FIT to detect ANL, the S was 30%, E: 84%, PPV: 13% and NPV: 94%. For low-risk adenomas the S was 13%, E: 84%, PPV: 17% and NPV:79%; for sessile serrated adenomas S was 16.7%, E: 87%, PPV:11%, and NPV: 91% and for CRC S:75%, E: 83%, PPV: 6 %, NPV: 99%. No post-procedure complications were observed. CONCLUSIONS: The diagnostic accuracy of a single round of FIT in our setting was similar to international results. However, since FIT diagnostic precision applied in this way was low, this fact emphasizes the need to carry out the test on an annual or biannual basis in order to achieve an effective CRC screening program.