Many patients experience bowel complaints after a total mesorectal excision for rectal cancer, such as: anal incontinence for feces, frequency and clustering of bowel movements, urgency and soiling. These symptoms are often referred to as low anterior resection syndrome (LARS) symptoms. The symptoms may be evaluated by the LARS questionnaire, the ColoRectal Functional Outcome (COREFO) questionnaire and the golden standard, a real-life stool diary. 

The aim of the study is to investigate whether the different LARS symptoms can be sufficiently well evaluated by the LARS or the COREFO questionnaire and this compared to the stool diary, in rectal cancer patients after low anterior resection surgery. We hypothesize that LARS symptoms can be sufficiently well evaluated by the LARS questionnaire and by the COREFO questionnaire as well.

Data from 77 patients treated for rectal cancer were included in this study. All of them underwent a total mesorectal excision and were recruited in 3 different hospitals. Data were collected at one month following surgery or, in case of a temporary ileostomy, one month after stoma closure. After consent, patients filled out the LARS-questionnaire (short questionnaire, including 5 items, 4-week recall period), COREFO-questionnaire (longer questionnaire, including 27 items, 2-week recall period) and a seven-day stool diary (more demanding for the patient to fill out and from the clinician to process). In the stool diary, patients were asked to keep track of frequency of ‘anal incontinence, bowel movements, urgency, clustering and soiling’ during 24 hours for 7 consecutive days. 

Canonical correlation analysis (multivariate analysis of correlation between sets of variables) was used to identify the amount of shared information between the different domains of the questionnaires and the stool diary. For each bowel complaint (anal incontinence for feces, frequency and clustering of bowel movements, urgency and soiling) all corresponding items were selected in the different evaluation tools. An overview of the number of items used for every evaluation tool is listed in Table 1. Canonical correlation analysis allows to compare multiple variables on both sides of the equation. In the case that two pairs of canonical variates were significantly correlated, a range was displayed concerning the correlation coefficient. In this study, the comparison was made between the LARS and COREFO questionnaire-items on the one hand and the stool diary-items on the other, to determine the magnitude of the possible relationship.

Results (overview in Table 2) demonstrated that items on anal incontinence for feces correlated (r = .470) significantly (p < .05) between the COREFO-questionnaire and the stool dairy. The fraction of information found in the COREFO-questionnaire that could be explained by the stool diary items was 13.5%.

The items on frequency of bowel movements were significantly (p < .05) correlated (r = .456) between the LARS-questionnaire and the stool diary. The fraction of information found in the LARS-questionnaire that could be explained by the stool diary items was 20.8%. Moreover, COREFO-items on frequency of bowel movements were also significantly (p < .05) correlated (r = .573-.587) with the stool diary items. The fraction of information found in the COREFO-questionnaire that could be explained by the stool diary items was 23.5%.

Lastly, items on soiling were significantly (p < .05) correlated (r = .515) between the COREFO-questionnaire and the stool diary and 20.3% of information found in the COREFO-questionnaire could be explained by the stool diary items.
The remaining items from the LARS-questionnaire (anal incontinence, clustering and urgency) and the COREFO-questionnaire (clustering and urgency) did not significantly correlate with the corresponding stool diary items, which means no overlap in information between sets could be found.

For the LARS-questionnaire, no item on soiling is represented. The COREFO-questionnaire consists of more items (such as social impact and medication use) than were used in the analyses, but these did not correspond with items from either the LARS-questionnaire or the stool diary.

Both questionnaires (LARS and COREFO) are valuable tools in assessing LARS symptoms developed after rectal cancer surgery. However, only one item of the LARS questionnaire, (frequency of bowel movements) showed sufficient agreement compared to the stool diary. In particular, the LARS questionnaire contained only 20.8% of the information regarding frequency of bowel movements, available in the stool diary.

For the COREFO questionnaire, three items showed sufficient agreement compared to the stool diary. Of information that the COREFO-questionnaire contained, 13.5%, 23.5% and 20.3% was available in the stool diary, regarding anal incontinence for feces, frequency of bowel movements and soiling, respectively.
Overall, moderate to high correlations were found, although the overlapping amount of information between the questionnaires and the stool dairy was rather small.

Both the LARS and the COREFO questionnaire are efficient tools to evaluate specific LARS symptoms after low anterior resection for rectal cancer. However, neither of the questionnaires has the potential to replace the stool diary entirely. In order to evaluate all aspects of the LARS, it seems essential to at least combine both questionnaires or ideally use a stool diary to optimize postoperative therapy for bowel complaints.