What is the recommended assessment and management for low anterior resection syndrome after sphincter‑preserving surgery for rectal cancer?

Management of Low Anterior Resection Syndrome (LARS)

All patients undergoing low anterior resection should receive supported self-management interventions immediately after surgery, undergo formal LARS-score assessment at 3 months, and be referred to specialist services if symptoms persist despite conservative measures. 1

Understanding LARS and Its Impact

LARS affects approximately 73% of patients after sphincter-preserving rectal cancer surgery, manifesting as variable bowel function, urgency, frequency, and emptying difficulties. 1 The syndrome significantly impairs quality of life, with patients experiencing social avoidance and substantial disability. 1 Importantly, spontaneous improvement after 3 months is rare—active intervention is required rather than watchful waiting. 1

The severity varies by treatment approach: in the RAPIDO trial, LARS occurred in 59% of patients receiving total neoadjuvant therapy versus 75% in the standard chemoradiotherapy group among those without stomas. 2 Neoadjuvant radiotherapy is independently and negatively associated with long-term improvement of LARS symptoms. 3

Assessment and Risk Stratification

Use the LARS-score questionnaire for both pre-operative severity assessment and systematic follow-up—it is the most practical patient-reported outcome measure for routine clinical use. 1 The questionnaire has been validated in multiple languages and should be administered at 3 months post-operatively. 1, 4

Key symptoms to assess include: 5

• Fecal incontinence (reported in 97% of studies)
• Stool frequency (80% of studies)
• Urgency (67% of studies)
• Evacuatory dysfunction (47% of studies)
• Gas-stool discrimination (34% of studies)

Algorithmic Treatment Approach

Immediate Post-Operative Phase (0-3 Months)

Initiate supported self-management interventions immediately after surgery for all patients. 1 This includes:

• Exclude comorbid conditions that worsen LARS: bile-acid diarrhea, pancreatic exocrine insufficiency, and small-intestinal bacterial overgrowth. 1
• Rule out overflow diarrhea, which represents a distinct pathophysiology requiring alternative management. 1

First-Line Management (If Symptoms Present at 3 Months)

Without intervention, bowel symptoms may take years to improve or may never improve; with targeted intervention, improvements typically occur within 3-4 months. 1

1. Colesevelam hydrochloride when bile-acid diarrhea is present or suspected—bile-acid sequestrants are particularly useful when the colon remains in continuity. 1

2. Bulking agents (fiber supplementation) to reduce stool clustering and improve consistency. 1

3. Consider ramosetron (5-HT receptor antagonist) for major LARS—a randomized controlled trial demonstrated safety and efficacy for relieving symptoms after sphincter-saving rectal cancer surgery. 4

4. Dietary modification in conjunction with medical therapy, though evidence shows only modest effect. 6

Second-Line Management (If First-Line Fails)

If symptoms persist beyond 3 months and supported self-management has failed, refer to specialist services. 1

1. Systematic pelvic-floor (Kegel) exercises—these should be formally taught as they may improve functional outcomes. 1

2. Transanal irrigation (TAI) is advised for patients whose symptoms persist despite first-line measures—it is a key second-line intervention with increasing evidence of efficacy. 1, 6

Third-Line Management (Refractory LARS)

For patients who fail all conservative and second-line interventions:

1. Sacral nerve stimulation or tibial nerve stimulation may be considered, although further research is needed to define their precise role. 1

2. Permanent stoma formation (colostomy) should be discussed for a small proportion of patients with severe, refractory LARS who have failed all other interventions. 1 In one long-term follow-up study, 3.4% of patients required new stomas due to severe bowel dysfunction. 3

Critical Pitfalls to Avoid

• Do not assume spontaneous improvement after 3 months—active intervention is required, as symptoms rarely improve without treatment. 1
• Do not delay assessment—early active case finding is essential rather than watchful waiting. 1
• Do not perform objective testing to diagnose LARS—clinical assessment using the LARS-score questionnaire is sufficient. 1
• Do not overlook the negative impact of neoadjuvant radiotherapy on long-term LARS outcomes when counseling patients pre-operatively. 3

Long-Term Perspective

Most rectal cancer survivors with LARS continue to improve beyond 3 years after proctectomy, with 31.5% of patients reporting improvement from major to no/minor severity between 39 and 83 months post-surgery. 3 However, this improvement is significantly less likely in patients who received neoadjuvant radiotherapy. 3

The mean LARS score improved from 29.5 to 18.6 over this extended follow-up period, demonstrating that long-term improvement is possible with appropriate management, contrary to the common belief that improvement only occurs within the first 2 years. 3