AIM To assess proportions, related conditions and survival of interval cancer(IC).METHODS The programme has a linkage with different clinical databases and cancer registers to allow suitable evaluation. This evaluation involves the detection of ICs after a negative faecal inmunochemical test(FIT), interval cancer FIT(IC-FIT) prior to a subsequent invitation, and the detection of ICs after a positive FIT and confirmatory diagnosis without colorectal cancer(CRC) detected and before the following recommended c o l o n o s c o p y, I C-c o l o n o s c o p y. W e c o n d u c t e d a retrospective observational study analyzing from January 2009 to December 2015 1193602 invited people onto the Programme(participation rate of 68.6%).RESULTS Two thousand five hundred and eighteen cancers were diagnosed through the programme, 18 cases of IC-colonoscopy were found before the recommended follow-up(43542 colonoscopies performed) and 186 IC-FIT were identified before the following invitation of the 769200 negative FITs. There was no statistically significant relation between the predictor variables of ICs with sex, age and deprivation index, but there was relation between location and stage. Additionally, it was observed that there was less risk when the location was distal rather than proximal(OR = 0.28, 95%CI: 0.20-0.40, P < 0.0001), with no statistical significance when the location was in the rectum as opposed to proximal. When comparing the screen-detected cancers(SCs) with ICs, significant differences in survival were found(P < 0.001); being the 5-years survival for SCs 91.6% and IC-FIT 77.8%.CONCLUSION These findings in a Population Based CRC Screening Programme indicate the need of population-based studies that continue analyzing related factors to improve their detection and reducing harm. AIM To assess proportions, related conditions and survival of interval cancer (IC) .METHODS The program has a linkage with different clinical databases and cancer registers to allow suitable evaluation. This evaluation involves the detection of ICs after a negative faecal inmunochemical test (FIT) , interval cancer FIT (IC-FIT) prior to a subsequent invitation, and the detection of ICs after a positive FIT and confirmatory diagnosis diagnosis without colorectal cancer (CRC) and before the following recommended colonoscopy, ICC olonoscop y. W econducteda retrospective observational study analyzing from January 2009 to December 2015 1193602 invited people onto the Program (participation rate of 68.6%). RESULTS Two thousand five hundred and eighteen cancers were diagnosed through the program, 18 cases of IC-colonoscopy were found before the recommended follow-up (43542 colonoscopies performed) and 186 IC-FIT were identified before the following invitation of the 769200 negative FITs. There was no significant significant relation between the predictor variables of ICs with sex, age and deprivation index, but there was relation between location and stage. Additionally, it was observed that there was less risk when the location was distal rather than proximal (OR = 0.28, 95% CI: 0.20-0.40, P <0.0001), with no statistical significance when the location was in the rectum as opposed to proximal. When comparing the screen-detected cancers (SCs) with ICs, significant differences The 5-year survival for SCs 91.6% and IC-FIT 77.8% .CONCLUSION These findings in a Population Based CRC Screening Program indicate the need of population-based studies that continue analyzing related factors to improve their detection and reducing harm.