The nationwide Dietary Intake after Diagnosis and Colorectal Cancer Outcomes (PLCRC-PROTECT) cohort: Study design, clinical characteristics and baseline health behaviors.

Purpose: The nationwide Dietary Intake After Diagnosis and Colorectal Cancer Outcomes (PROTECT) study is a prospective cohort study investigating how lifestyle-related factors including dietary intake and physical activity are associated with health-related quality of life (HRQoL), recurrence, and survival after a colorectal cancer (CRC) diagnosis.

Methods: Patients participating in the Prospective Dutch Colorectal Cancer (PLCRC) cohort with newly diagnosed stage I to IV colorectal cancer were recruited for PROTECT shortly after diagnosis, between 2015 and 2022. While patient-reported quality of life, physical activity, and sedentary behavior, as well as body composition data are available from PLCRC, patient-reported measurements in PROTECT included anthropometrics, dietary intake, dietary supplement use, and taste and smell alterations. Clinical data was obtained from the Netherlands Cancer Registry.

Results: Patients returned baseline questionnaires after a median of 43 days (IQR: 28-59) after diagnosis. At diagnosis, the 974 participants' median age was 65 years (IQR: 58, 72), 59 % were male, 59 % had overweight/obesity, and 28 % stage I, 25 % stage II, 40 % stage III, and 6 % stage IV disease. Dietary supplements more frequently used were multivitamins (35 %), vitamin D (30 %), vitamin C (15 %), and magnesium (14 %). Around diagnosis, changes in taste ability were reported by 6 % of patients, while 2 % experienced changes in smell, and 16 % reported experiencing a dry mouthfeel. In total, 24 % adhered to ESPEN dietary guideline of ≥ 25 kCal/kg/day plus ≥ 1 gram protein/kg/day, while 45 % adhered to international physical activity guidelines.

Conclusion: PROTECT is a unique nationwide cohort of CRC patients with a wealth of lifestyle-related data obtained through patient-reported measurements, of which baseline assessments were presented. PROTECT participants will be followed until deceased or lost to follow-up to collect all clinical outcome data. PROTECT will inform clinical and public health guidelines on physical activity and dietary patterns for improving CRC outcomes and survivorship.