The impact of colorectal cancer screening on incidence and stage IV disease in the Netherlands.

Abstract

3531 Background: Population-based screening for colorectal cancer (CRC) aims to decrease incidence and mortality due to precancerous polyp removal, early detection and early treatment of CRC. In the Netherlands, phased introduction of a biennial fecal immunochemical hemoglobin test started in 2014 for individuals aged 55-75. This evaluation of the national data focuses on the initial effect of CRC screening on incidence and stage distribution and the impact on stage IV disease. Methods: All CRC patients diagnosed in the Netherlands between 2009 and 2018 were selected from the Netherlands Cancer Registry (NCR). Patients were linked to the Dutch national pathology registry (PALGA) to identify screen-detected tumors. Results: The NCR identified 137,717 CRC patients between 2009 and 2018. The incidence within screening age (55-75 yr) of all CRC stages showed an initial peak after introduction of screening in 2014, followed by a continuous decrease for all stages. CRC incidence outside the screening age did not show these explicit changes between 2009 and 2018. In 2018, the incidence of stage IV CRC within screening age was lower than the level at the start of the screening program. Stage distribution within screening age shifted towards earlier stages in the screening period (2014-2018) compared to the period before screening (2009-2012) (stage I: 31% vs. 18%, stage II: 22% vs. 26%, stage III: 29% vs. 31%, Stage IV: 18% vs. 25%, respectively). In the period 2014-2018 and within screening age, the ratio of screen-detected and symptom-detected tumors was highest in stage I (47%:53%) and lowest in stage IV (9%:91%). Screen-detected compared to symptom-detected stage IV patients diagnosed in the period 2014-2018 and within screening age had more frequently single organ metastases (74.5% vs 57.4%, p < 0.001), higher resection rate of the primary tumor (57.5% vs. 41.3%; p < 0.001) and higher local treatment rate of metastases (40.0% vs. 23.4% p < 0.001). The median overall survival of screen-detected stage IV patients was significantly longer than that of symptom-detected stage IV patients (31.0 months (95% CI: 27.7 – 34.3) vs. 15.0 months (95% CI: 14.5 – 15.5), p < 0.001). Conclusions: The initial results of the introduction of CRC screening in the Netherlands showed a favorable trend on CRC incidence and stage distribution. Screen-detected patients with stage IV disease had less extensive disease, resulting in better treatment options and improved survival.