The purpose of the study is to investigate whether the information about a doctor or possibility to choose doctor's gender included in invitation letter is associated with attendance rate to screening colonoscopy.

Study is performed as a part of NordICC (Clinical trials NCT 00883792) trial, which is intended to investigate the effect of screening colonoscopy on colorectal cancer incidence and mortality. NordICC trial is a multicenter, randomized study conducted in Norway, Sweden, Netherlands and Poland.

This study is designed to assess two factors potentially influencing patients attendance. These two factors are: identification of particular doctor performing examination and the possibility of choosing doctor's gender.

Inclusion Criteria:

• Individuals 55-64 years of age randomized to the screening arm of the NordICC trial in Poland

Exclusion Criteria:

• previous open colorectal surgery
• need for long term attention and nursing services (somatic or psychosocial reasons, mental retardation)
• ongoing cytotoxic treatment or radiotherapy for malignant disease
• severe chronic cardiac or pulmonary disease (NYHA III and IV)
• lifelong anticoagulant treatment
• coronary or cerebrovascular incident requiring hospitalization during the last three months
• residence abroad
• return of unopened letter of invitation and/or reminder, or message of death of the subject (not updated in Population Registry)
• failure to provide written informed consent
• screening colonoscopy within 10 years