This observational follow-up study of the randomized trial (RCT) DIQOL investigates long-term effects of an intervention with quality of life (QoL) diagnosis and therapy on present QoL, survival, and recurrence-free survival of colorectal cancer survivors more than 5 years after surgery.

Moreover, patients' experiences with aftercare for colorectal cancer during the COVID-19 pandemic and their recollections of their illness and therapy are examined.

In a complex intervention a clinical pathway with quality of life (QoL) diagnosis and tailored therapy had been developed for patients with colorectal cancer and its effectiveness was evaluated in a randomized trial (RCT DIQOL, NCT02321813, Klinkhammer-Schalke et al, 2020). In the RCT DIQOL a total of 220 patients were randomised (1:1) into two groups: a care pathway, including QoL-profiles consisting of 13 QoL scales plus specific therapeutic recommendations forwarded to the patient's doctor (intervention) or standard postoperative care (control). QoL was measured (EORTC QLQ-C30, QLQ-CR29) in all patients after surgery and during aftercare (3, 6, 12, 18 months postoperatively). A need for QoL therapy was defined as a score <50 points on at least one QoL scale. It was demonstrated that the proportion of patients with a need for QoL therapy was significantly lower in intervention group patients at 12 months after surgery (primary endpoint).

Until now, it is unclear whether there are also long-term benefits of QoL diagnosis and therapy. Therefore, the aim of this observational, cross-sectional follow-up study of the RCT DIQOL is to investigate long-term effects of the intervention on present QoL (EORTC QLQ-C30, QLQ-CR29), overall survival, and recurrence-free survival more than 5 years after surgery by comparing former intervention and control group patients. Moreover, participants will be asked for their experiences during aftercare in relation of the COVID-19 pandemic and for their recollection of their illness and therapy. Data are collected via questionnaire.

Inclusion Criteria:

• former participants of the RCT DIQOL with a primary diagnosis of colorectal cancer between 01/2014 and 10/2015 who did not refuse to participate during the RCT
• informed consent

Exclusion Criteria:

- none -

Former participants of the RCT DIQOL with a primary diagnosis of colorectal cancer between 01/2014 and 10/2015 who had been surgically treated in one of four participating certified centers for colorectal cancer (Krankenhaus Barmherzige Brüder Regensburg, Germany; Caritas-Krankenhaus St. Josef Regensburg, Germany; Klinikum Neumarkt, Germany; Klinikum St. Elisabeth Straubing, Germany). Originally, 220 patients were included in the RCT DIQOL. Of the 220 participants who were included in the RCT 12 patients refused participation during the trial so that the final sample for the follow-up study encompasses 208 patients. The questionnaire is mailed to survivors of this cohort. Overall survival and recurrence-free surival will be analzyed in all 208 former study participants.

Anonymized IPD that underlie the results in a publication are planned to be made available upon request of scientists.

6 months after date of publication until 60 months after date of publication

Data will be made available to other scientists upon request for nonprofit research. The contact address is monika.klinkhammer-schalke@ur.de. Scientists are required to send their predefined statistical analysis plan. Together with the scientific review board of the Tumor Center Regensburg a decision will be made based on the quality and usefulness of planned statistical analysis. In case of a positive decision the scientist is required to sign a contract for data usage before receiving anonymized IPD.