Bowel-Related Symptoms and Dietary Fiber Intake in Colorectal Cancer Survivors

Colorectal cancer (CRC) survivors frequently report bowel-related symptoms, but longitudinal data are scarce and diet has not been extensively investigated in relation to bowel-related symptoms.

To investigate the prevalence of bowel-related symptoms as well as their association with dietary fiber intake until 5 years after CRC diagnosis.

This prospective cohort study using data from the Colorectal Cancer: Longitudinal, Observational Study on Nutritional and Lifestyle Factors (COLON) study included CRC survivors with stage I-IV disease recruited at diagnosis from 11 hospitals in the Netherlands between August 2010 and February 2020. CRC survivors were followed up until 5 years after diagnosis. Data were analyzed between April 2024 and March 2025.

Clinical data including CRC treatment strategy, retrieved from hospital records and national registries, and habitual dietary fiber intake, assessed by a food frequency questionnaire, at 6 months, 2 years, and 5 years after CRC diagnosis.

Prevalence of self-reported diarrhea, constipation, flatulence or bloating, frequent stools, mucus in stools, or false urgency at 6 months, 2 years, and 5 years after diagnosis, obtained via a questionnaire. The validated European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire Core 30 (EORTC QLQ-C30) was also used to evaluate prevalence of moderate-to-severe diarrhea or constipation and health-related quality of life (HRQOL) at these time points. Odds ratios (ORs) for associations between fiber intake and bowel-related symptoms (yes or no) were calculated using multivariable logistic regression.

Among 1751 CRC survivors who underwent surgery and were included in the analysis, median age at diagnosis was 66 years (IQR, 61-71 years), and 1115 (63.7%) were men. Bowel-related symptoms were reported by 817 of 1751 survivors (46.7%) at 6 months, 614 of 1511 (40.6%) at 2 years, and 290 of 812 (35.7%) at 5 years after diagnosis. At 6 months after diagnosis, symptoms were predominantly reported by survivors who had received chemotherapy (260 of 446 [58.3%]), whereas symptoms at 2 and 5 years occurred mostly in those who received radiotherapy (86 of 160 [53.8%] at 2 years and 47 of 92 [51.1%] at 5 years). Of the studied bowel-related symptoms, diarrhea was associated with the lowest HRQOL score (B, -9.6; 95% CI, -14.0 to -5.2) at 5 years after diagnosis. In multivariable logistic regression analyses, higher fiber intake (per 10-g/d increment) was associated with a significantly lower prevalence of moderate-to-severe diarrhea at 6 months (OR, 0.44; 95% CI, 0.28-0.70) and 2 years (OR, 0.53; 95% CI, 0.30-0.94) after diagnosis, but the association was not statistically significant at 5 years (OR, 0.43; 95% CI, 0.16-1.13).

In this cohort study of CRC survivors, the prevalence of bowel-related symptoms was considerably high during the 5 years after diagnosis, highlighting a need for effective symptom management. Higher dietary fiber intake was associated with a lower prevalence of diarrhea, suggesting a potential role of diet in management of bowel-related symptoms in CRC survivors.