The primary objective of this study was to evaluate the impact of a constructed shared decision (SDM) intervention (offering an option between colonoscopy and immunochemical collapsible occult blood testing (fecal immunochemical test; FIT)) on improving the incidence of high colonoscopy stromal in patients aged 40-49 years with a close relative suffering from colorectal cancer, compared to standard care (direct referral for colonoscopy).

Inclusion Criteria:

• Age 40 to 49 years at the time of recruitment.
• At least one immediate family member (biological parent, sibling, or child) has been pathologically diagnosed with colorectal cancer.
• Able to read, understand, and provide prior consent.
• Willing to be randomly assigned to any research group and complete all research procedures.

Exclusion Criteria:

• A personal history of colorectal cancer or inflammatory bowel disease (Crohn's disease or ulcerative colitis).
• Presence of warning signs of colorectal cancer requiring diagnostic evaluation rather than screening (e.g., unexplained rectal bleeding, significant involuntary weight loss, persistent changes in bowel habits).
• Presence of comorbidities that may contraindicate colonoscopy.
• Having undergone colonoscopy within the past three years.
• Inability to read, understand, and provide written informed consent.