Is bowel habit linked to colorectal cancer? – Results from the EPIC-Norfolk study

https://doi.org/10.1016/j.ejca.2008.10.002Get rights and content

Abstract

Bowel habit has been associated with colorectal carcinogenesis; however, findings from epidemiologic studies have been limited and inconsistent. The aim of this study was to explore the association between bowel habit and colorectal cancer (CRC) risk in the UK-Norfolk arm of the European Prospective Investigation Into Cancer and Nutrition (EPIC-Norfolk), a study of 25,663 men and women aged 45–79 years at entry. Having loose stools compared to soft stools was associated with an approximately 3-fold increased risk, and the association remained significant when lifestyle factors and bowel habit variables were included as covariates in the model (odds ratio (OR), 2.80; 95% confidence interval (CI), 1.41–5.56). The significantly elevated risk estimate persisted when we further excluded CRC cases within 3 years of follow-up. Frequency of bowel movement, stool quantity, feeling discomfort and laxative use was not overall associated with CRC risk. These findings suggest that having loose stools may be an indicator of colorectal cancer risk.

Introduction

Colorectal cancer (CRC) is the third most common cancer worldwide after lung and breast cancer in 2002 and the second most common incident form of cancer in Europe in 2004 (376,400 cases, 13% of all incident cases).1, 2 Around 100 new cases of CRC are diagnosed each day in the United Kingdom (UK) in 2006, being the second most common cause of death from cancer in the country.3

Constipation and infrequent bowel movement have long been suggested to be risk factors for colorectal cancer (CRC). In the early 1970s, Burkitt and colleagues hypothesised that bowel flora convert bowel contents to carcinogens or co-carcinogens by a time-dependent process.4, 5 They suggested that low bowel movement frequency from low fibre intake slows intestinal transit thereby prolonging mucosal contact with putative carcinogens in the colonic lumen. However, only a few studies have examined this hypothesis in relation to CRC risk despite its biological plausibility, and prospective studies investigating bowel habit are particularly sparse.

In 1993, a meta-analysis summarised results of nine published case-control studies examining bowel habit and demonstrated a statistically significant increased risk of CRC with constipation or infrequent bowel movement (odds ratio (OR), 1.48; 95% confidence interval (CI), 1.32–1.66).6 However, the individual case-control studies were relatively inconsistent in defining constipation or infrequent bowel movement. In addition, two recent large prospective studies which showed null or negative associations between infrequent bowel movement and the risk of CRC do not agree with the finding from the meta-analysis.7, 8

Conversely, it has also been postulated that intestinal hurry may be a risk factor for CRC having an irritant action on the mucosa of the large bowel, resulting in hyperplasia, dysplasia and neoplasia.9 To date, however, only three case-control studies10, 11, 12 and two prospective studies8, 13 assessed this hypothesis and provided equivocal evidence on the association of loose stools or frequent bowel movement and CRC risk.

Studies often fail to support an association between laxative use and CRC risk7, 12, 14, 15 although commercial laxative use is widely spread, and the uncontrolled long-term abuse of self-administered laxatives may have a harmful effect and may therefore cause several health problems.16

Overall, previous epidemiologic studies, mostly case-control studies, which examined bowel habit in relation to the development of CRC thus far have failed to support conclusively any of the proposed hypotheses. One of the possible explanations of these discrepancies may be that constipation and diarrhoea are common symptoms of CRC, and the relevant time period when risk factors act in the process of cancer development is often unknown.7

The aim of this nested case-control study was to investigate the prospective association between bowel habit, including bowel movement frequency, consistency, quantity, feeling of discomfort during bowel movement, laxative use and risk of CRC in participants of the UK-Norfolk cohort of the European Prospective Investigation Into Cancer and Nutrition (EPIC-Norfolk) study.

Section snippets

Study population

The EPIC-Norfolk Study is an ongoing prospective study of 25,663 men and women aged between 45 and 79 years who were residing in Norfolk, United Kingdom, and were recruited from general practice registers. The design and study methods have been described previously.17 The study was approved by the Norwich Ethics Committee, and participants gave signed informed consent.

Case ascertainment and control selection

Incident CRC cases (International Statistical Classification of Diseases and Related Health Problems (ICD) 9th revision,

Results

During 12 years of follow-up, 159 cases with no history of CRC at baseline provided information on bowel habit and were therefore included in the analyses. Cases and controls were similar with respect to baseline characteristics such as weight, height, WHR, BMI and the distribution of smoking status, HRT use and physical activity (Table 1). Cases reported less energy, dietary fibre and total meat intake. However, none of these differences was statistically significant.

The proportion of cases

Discussion

To our knowledge, this is the first prospective study using a nested case-control design that has reported a significant association between bowel movement consistency and CRC risk. In particular, having loose stools appeared to be a strong risk factor for incident CRC, especially for colon cancer, with an approximately 3-fold increased risk, and this was not substantially changed by adjusting for potential confounding factors or excluding the first three years of follow-up. Two recent Japanese

Conflict of interest statement

None declared.

Acknowledgements

We thank all the participants and the entire EPIC-Norfolk team. EPIC-Norfolk is supported by research programme grant funding from the Cancer Research UK and Medical Research Council with additional support from the Stroke Association and Research into Ageing.

References (29)

  • A. Sonnenberg et al.

    Constipation and cathartics as risk factors of colorectal cancer: a meta-analysis

    Pharmacology

    (1993)
  • L. Dukas et al.

    Prospective study of bowel movement, laxative use, and risk of colorectal cancer among women

    Am J Epidemiol

    (2000)
  • G. Kune

    Causes and control of colorectal cancer: a model for cancer prevention

    (1996)
  • L.G. Dales et al.

    A case-control study of relationships of diet and other traits to colorectal cancer in American blacks

    Am J Epidemiol

    (1979)
  • Cited by (0)

    View full text