The currently developed implementation study aims to evaluate if a patient-led home-based follow-up approach is successful, improves quality of life, reduces anxiety and lessens fear of cancer recurrence during the years after surgical treatment of colorectal cancer (CRC).

As the available literature implies that intensive postoperative surveillance has no impact on (cancer-specific) survival outcomes in patients after curative intent surgery for CRC, critical appraisal of the current follow-up practice and guidelines is needed. Although patients in the referenced randomized controlled trials were included roughly 5 - 15 years ago, treatment for recurrent colorectal cancer has seen little to no change since then. Therefore, efforts to improve the current standard of follow-up in patients with CRC should focus on ameliorating quality of life and cost-effectiveness, rather than survival. It provides an opportunity to support patients emotionally, to evaluate treatment effects and complications, and to inform them on their individual prognosis. This is especially true considering the growing importance of value based healthcare and patient reported outcomes in medicine. The investigators therefore propose a patient-led home-based follow-up approach. This follow-up strategy primarily consists of carcinoembryonic antigen (CEA) level monitoring at home, but additional counselling/diagnostic testing remains possible if desired by patients. In this way the investigators hope to meet the individual needs of patients during follow-up and to improve quality of life outcomes, while achieving equal or greater societal cost-effectiveness.

Inclusion Criteria:

• Histologically confirmed colorectal adenocarcinoma without distant metastasis and treated with curative intent surgical resection less than 6 months ago
• Scheduled or currently undergoing postoperative surveillance according to national guidelines
• Written informed consent by the patient

Exclusion Criteria:

• Patients with a severely complicated postoperative course, needing in hospital follow-up longer than 6 months postoperatively
• Patients enrolled in other studies that require strict adherence to any specific follow-up practice with regular imaging - yearly or more frequent - of the abdomen and/or thorax
• Patients with comorbidity or other malignancy that requires imaging of the abdomen and/or thorax every year or more frequent
• Inability to complete the questionnaires due to illiteracy and/or insufficient proficiency of the Dutch language

Patients who are 18 years or older who received curative intent surgical treatment for CRC, and who (will) undergo postoperative surveillance are eligible. Patients can be included up to 6 months after surgery.