This study analyzed the degree of bowel dysfunction and risk factors after MIS in patients with rectal cancer. Preoperative RT and HSA were independently associated with multiple symptoms of bowel dysfunction included in WS and LS. The results of this study provided the probability of suffering from each symptom according to the type of anastomosis and with or without preoperative RT. Treatment strategies for patients with locally advanced rectal cancer are complex [29]. Patients should be informed about the possibility of postoperative bowel dysfunction before deciding on treatment for rectal cancer. Moreover, these results clearly reveal the discrepancies between the WS and LS.
Figure 4 helps us visualize the characteristics of LS and the discrepancies between the two scores. Clustering (93.0%) and urgency (78.9%) occurred almost certainly in the patients of this cohort. Weighted scores of these two subscales are exceptionally high in LS (urgency ranges 0–16 and clustering ranges 0–11); therefore, patients are easily categorized into minor or major LARS. Comparable to these results, the prevalence of minor and major LARS has been reported to range from 20 to 28% and from 38 to 62%, respectively [15, 18]. A previous cross-sectional study showed that minor LARS occurred in 24.3% even in the general population, therefore, the authors suggested that minor LARS reported after LAR should not simply be interpreted as a poor outcome caused by surgery [30]. Furthermore, 80% and 21% of our patients with minor and major LARS did not report lifestyle alterations, respectively. The most significant difference between WS and LS is that the former includes the question of lifestyle alterations. From the present results of the WS, patients reported lifestyle alterations when they need to wear a pad because of incontinence for liquid or solid stools. The results were comparable to those of a previous report [31]. Even among patients with major LARS, there were patients with low WS (< 10) if they did not experience incontinence for liquid or solid stools. Recent research has shown that 82.9% and 28.6% of the patients with minor and major LARS had low WS (0–5 points), respectively [22]. Another study demonstrated that 24% of the patients with major LARS did not experience bowel dysfunction and impaired QOL. In contrast, 24% of the patients with no LARS received medication due to evacuation dysfunction. They indicated that LS may under- or overestimate the severity of bowel dysfunction after SPS [20]. The results of this study are consistent with those of previous studies, and it has been suggested that assessing postoperative bowel dysfunction using only a single scoring tool is insufficient. More research is needed to confirm which combination of assessment tools is most practical, or additional questionnaire tools may need to be established.
Several risk factors for bowel dysfunction after SPS have been described, including high age, male sex, distal tumor location, lower anastomosis level, creation of diverting ileostomy, anastomotic leakage, ISR, and preoperative RT [7, 14, 20, 32–35]. Based on these results, HSA was an independent risk factor for poor WS (> 10), and distal tumor location and preoperative RT were independent risk factors for major LARS. WS and LS are practical and are well known in clinical practice. Therefore, these scores can help identify patients who need to use the medication because of bowel dysfunction [20, 21]; however, they do not provide patients with helpful information about their defecation function. Present results revealed independent risk factors for individual subscales of WS and LS. The 2-year incidence of each symptom was presented according to the presence or absence of preoperative RT and HSA. Therefore, our study provides practical data to facilitate patient perception of potential bowel dysfunction after SPS.
In this study, bowel dysfunction at the 2-year after surgery was analyzed and compared with that at 1-year after surgery. WS and LS decreased from 1- to 2-year after surgery or stoma closure. However, the differences were not statistically significant and were comparable to previous reports [36, 37]. Cheong et al. evaluated the bowel function of patients with rectal cancer who underwent double-stapled anastomosis and HSA using WS and LS. At the 3-year after surgery, 52.2% of patients in the study had major LARS, which was similar to our result at 2-year after surgery (52.1%) [38]. Chen et al. demonstrated the LS of patients with rectal cancer located within 15cm from AV. The median interval between the surgery and assessment of bowel function was 14.6 years, and 46%, 22%, and 32% of the patients had major, minor and no LARS, respectively [21]. Additionally, Vather et al. analyzed colonic motor pattern using high-resolution manometry. Patients who had undergone distal colorectal resection and had normal bowel function were included tin the study. Their study’s median interval between index resection and manometry evaluation was 8 years. The authors revealed that motor patterns were restored and became comparable to those of healthy controls [39]. A systematic review assessed the instruments used to evaluate bowel function after SPS. Approximately half and 20% of the included studies assessed the bowel function at 1-year and 2-year after surgery, respectively [15]. Although secular improvement in bowel function is expected, it is yet to be established when the symptoms are fixed. Further research is required to determine when bowel dysfunction is categorized by the instruments, including WS and LS.
This study has certain limitations. First, this was a single-center, retrospective study with a relatively small sample size. Our previous report demonstrated that WS was highest in patients who underwent ISR after neoadjuvant RT [7]. Second, this cohort included only six patients treated with RT and ISR; therefore, further research with a larger sample size is required. Moreover, information was unavailable on whether partial, subtotal, or total ISR was performed in this study cohort. In some patients who underwent ISR, the ISR type was not described in the operation report.
In conclusion, this study explored the incidence and risk factors of each symptom of bowel dysfunction. The characteristics of LS and the potential points of difference between LS and WS were clarified. Although LS is beneficial and practical, the blind acceptance of only one instrument may cause under- or overestimation of bowel dysfunction after SPS. A consistent effort is required to optimize the existing instruments and establish a new one.