RESPONSE: Colorectal cancer survivors’ follow-up care – now digital and need-based. A national interventional effectiveness trial for stage I and II patients.

The overall aim of this study is to investigate whether individualized, need-based recurrence sur-veillance can improve health related QoL (HRQoL), without compromising OS and RFS or in-creasing costs. The objective of the study is to design a ctDNA and ePROM guided surveillance program for stage I and low risk stage II patients with CRC, and conduct a trial where this program can be compared to standard-of-care recurrence surveillance in terms of HRQoL, OS, RFS, and cost-effectiveness. The study Intervention Group will receive a ctDNA and ePROM guided surveillance program, which includes: 1) serial ctDNA monitoring to identify individuals with high risk of recurrence, 2) serial ePROM monitoring to identify ‘organ-specific late effects’ and ‘biopsychosocial late effects’, 3) planned and systematic management/intervention of recurrence and late effects, and 4) personalized self-managed follow-up by a digital care guide as a smartphone application. The standard-of-care group receives standard-of-care CT-imaging based recurrence surveil-lance.