Table 3.

Detailed schedule of all observations to be performed during the clinical trial

Procedure	Screening Visit for eligibility	Visit 1 Start of treatment	Visit 2 End of rehabilitation	Collection of data via questionnaire/ phone and blood/urine sampling by GP
Rehabilitation clinic	Admission	–	Discharge	–
Time-point of data assessment	–	Day 1	Day 12–21	Week 13–16
Planned doses of vitamin D3 per day	–	Individualized initial dose (20,000 or 40,000 IU, followed by 2000 IU per day) for day 1–11	Maintenance dose of 2000 IU per day for day 12–21	–
Inclusion/exclusion criteria	●	●
Written informed consent	●
Randomization		●
Trial medication intake		●	●
Subject diary regarding days of drug administration		●	●
Physical examination (weight, height, waist circumference)	●
Urinary pregnancy test for women of childbearing potential	●
Assessment of CRC treatment	●			●
Concomitant diseases / Medical history	●
Concomitant medication	●			●
Query about concomitant use of vitamin D3 or vitamin D analogs in self-medication in addition to trial medication				●
Fatigue	●			●
Functional well-being, QoL, infection frequency, and depression	●			●
Blood sampling for biomarker efficacy and safety endpoints	●		●	●
Urine sampling for safety endpoints	●		●	●
(S)AE recording and protocol deviations		●	●	●

Abbreviations: CRC colorectal cancer; GP general practitioner; QoL Quality of life; SAE Serious adverse event