Background: Colorectal cancer (CRC) screening programmes require high levels of participation in order to reduce mortality. To improve participation rates, it is necessary to identify the health risk factors and social inequalities associated with non-participation. Methods: A systematic review was conducted between June and September of 2019 in six databases: CINHAL, Medline, Scopus, Social Sciences Citation Index, Embase and PsycINFO. Studies assessing the relationship between health risk factors, participation in preventive activities and participation in CRC screening were included. Methodological assessment was carried out according to the Quality Assessment Tools of the National Heart, Lung and Blood Institute. Results: A total of nine studies that analyze participation in both organized and opportunistic screening programmes using any type of screening method were finally selected. Data were mainly self-reported although in two studies medical records were also studied. We identified several variables: gender, body mass index, consultation with a doctor or a specialist, educational level, employment, health insurance, residence, ethnicity, age, marital status, income, other preventive activities, obesity, physical activity, smoking, family history of CRC and general health status. Conclusion: The scarcity of studies linking risk factors, social inequalities and participation in preventive activities for participation in screening in the same study makes it difficult to reach definitive patterns related to non-participation in CRC screening programmes. Nevertheless, being under 60, obese, smoker and sedentary have shown an association with non-participation as well as not visiting a doctor.

Using the algorithm of the World Endoscopy Organisation (WEO), we have studied retrospectively all colorectal cancers, both detected and non-detected by the Basque Country screening programme from 2009 to 2017. In the screening programme 61,335 colonoscopies were performed following a positive Faecal Immunochemical test (FIT) (≥20 µg Hb/g faeces) and the 128 cases of post-colonoscopy colorectal cancer (PCCRC) detected were analysed. Among them, 50 interval type PCCRCs were diagnosed (before the recommended surveillance), 0.8 cases per 1000 colonoscopies performed, and 78 non-interval type PCCRCs (in the surveillance carried out at the recommended time or delayed), 1.3 per 1000 colonoscopies. Among the non-interval type PCCRCs, 61 cases were detected in the surveillance carried out at the recommended time (type A) and 17 when the surveillance was delayed (type B), 1 case per 1000 colonoscopies performed and 0.28 cases per 1000 colonoscopies performed, respectively. Interval type PCCRC is less frequent than non-interval type PCCRC. In interval type PCCRCs, CRCs detected in advanced stages (stages III–IV) were significantly more frequent than those detected in early stages, compared to those of non-interval type PCCRCs (OR = 3.057; 95% CI, 1.410–6.625; p < 0.005). Non-interval type B PCCRCs are less frequent than non-interval type A PCCRCs, but the frequency of advanced stages is higher in interval type B PCCRCs.

Objective High participation determines the success of colorectal cancer screening programmes in reducing incidence and mortality. The factors that determine participation must be studied from the perspective of professionals that implement the programme. The aim was to identify factors that facilitate or hinder the participation of the invited people in the bowel cancer screening programme of the Basque Country (Spain) from professional's perspective. Methods Qualitative design based on individual interviews and focus groups. Thirty-eight primary care professionals who implement the programme participated (administrative staff, nurses and general practitioners). Thematic analysis was performed. Results Professionals show high satisfaction with the programme, and they believe firmly in its benefits. Facilitators for participation include professionals' commitment to the programme, their previous positive experiences, their optimistic attitude towards the prognosis of cancer and their trust in the health system and accessibility. Barriers include invitees' lack of independence to make decisions, fear of a positive test result and patient vulnerability and labour mobility of the health professionals. Conclusions Professionals show a high degree of involvement and identify primary care is an appropriate place to carry out disease prevention. They identify the closeness to patients, the personal attitude and the characteristics of the health system as key factors that influence participation.