What is the standard treatment for rectal cancer?

Standard Treatment for Rectal Cancer

The standard treatment for localized rectal cancer is surgical resection by an experienced surgeon with total mesorectal excision (TME), preceded by neoadjuvant chemoradiotherapy for locally advanced disease (T3 or greater), followed by adjuvant chemotherapy for node-positive disease. 1, 2

Treatment Algorithm Based on Clinical Stage

Early Stage Disease (T1-T2, N0)

• Surgical resection with TME is the standard approach, with sphincter preservation attempted whenever anatomically feasible 1, 2
• For very low tumors (lower third of rectum), preoperative radiotherapy may be indicated even for T2 disease because the distance to the mesorectal fascia is minimal 1
• Local excision may be considered only for carefully selected T1 tumors without poor prognostic factors, though this remains controversial 3, 4
• If resection achieves negative margins with no nodal involvement and no perirectal fat invasion, regular follow-up without adjuvant therapy is appropriate 2

Locally Advanced Disease (T3-T4, Any N+)

For intermediate-risk tumors (T3 with negative circumferential resection margin on MRI, some T4 with limited involvement, or N+ disease):

• Preoperative radiotherapy followed by TME is the standard to reduce local recurrence rates 1
• Short-course regimen: 25 Gy in 5 fractions over 1 week, followed by immediate surgery (<10 days) is a convenient, simple, and low-toxic option 1
• Alternative long-course regimen: 46-50.4 Gy in 1.8-2 Gy fractions with concurrent 5-FU (bolus, continuous infusion, or oral capecitabine) 1, 5
• Preoperative treatment is preferred over postoperative treatment because it is more effective and less toxic 1, 3

For high-risk, locally advanced tumors (T3 with positive circumferential resection margin, T4 with organ involvement):

• Preoperative chemoradiotherapy is mandatory: 50.4 Gy in 1.8 Gy fractions with concurrent 5-FU-based therapy 1
• Surgery should be performed 6-8 weeks after completion of chemoradiotherapy 1
• For very elderly patients (≥80-85 years) or those unfit for chemoradiotherapy, 5×5 Gy with 8-week delay before surgery can be considered 1

Node-Positive Disease (Dukes C)

• Postoperative chemotherapy with 5-FU plus folinic acid is recommended for all node-positive disease 1, 2
• This applies even after preoperative chemoradiotherapy if pathologic examination reveals positive nodes 2

Surgical Technique Considerations

Total mesorectal excision (TME) is mandatory for all rectal cancers, meaning the entire mesorectal fat including all lymph nodes must be excised without damaging the rectal fascia 1, 2

For lower third rectal tumors:

• Excision of the entire mesorectum is essential to reduce locoregional recurrence 2
• Abdomino-perineal resection (APR) is usually required 2
• Critical technical point: Dissection must stop at the levator plane from above and continue from below to avoid a "cone effect" that increases positive margin rates 1
• Epiplooplasty to fill the perineal wound is recommended to reduce complications 2

Metastatic Disease at Presentation

Resectable Metastases (Oligometastatic Disease)

• Simultaneous rectal and hepatic surgery is standard if hepatectomy involves ≤3 segments 1, 2
• Alternative: Hepatectomy or pulmonary metastasectomy 3 months after rectal surgery, depending on disease progression 1
• Neoadjuvant chemotherapy can be considered before surgery 1
• External-beam radiotherapy should be considered for the primary rectal tumor if complete resection is achieved 1

Multiple Symptomatic Metastases

• Systemic palliative chemotherapy is the standard treatment 1
• Regimen options: 5-FU plus folinic acid (de Gramont protocol) with or without oxaliplatin or irinotecan 1
• Capecitabine is an acceptable oral alternative to infusion 5-FU 5, 6
• Local treatment (surgery, radiotherapy, laser therapy) should be tailored to clinical symptoms 1
• Systemic chemotherapy can be combined with pelvic radiotherapy 1

Multiple Asymptomatic Non-Resectable Metastases

• There is no standard approach 1
• Locoregional treatment (surgery and/or radiotherapy) followed by palliative chemotherapy is an option 1

Incomplete Resection or Understaged Disease

If surgical clearance was incomplete (positive margins) or tumor was understaged preoperatively:

• Postoperative radiotherapy must be considered 2
• Minimum recommended dose: 50 Gy as external-beam irradiation 2
• Additional surgery with or without radiotherapy should be considered 1

Critical Pitfalls to Avoid

Surgical pitfalls:

• Inadequate mesorectal excision, particularly for lower third tumors, dramatically increases local recurrence 2
• Damaging the rectal fascia during TME worsens outcomes and increases local recurrence 1
• Using traditional APR technique for low tumors creates a "cone effect" leading to positive margins 1

Treatment sequencing errors:

• Omitting preoperative radiotherapy for T3 or greater disease increases local recurrence 1
• Using postoperative rather than preoperative radiotherapy when both are options—preoperative is more effective and less toxic 1, 3
• Delaying chemotherapy excessively in stage IV disease, as this is the only modality that improves survival 3

Adjuvant therapy omissions:

• Failing to give postoperative chemotherapy for node-positive disease 2
• Not considering postoperative radiotherapy when margins are positive or disease was understaged 2

Follow-Up Protocol

Standard examinations include:

• Clinical examination 1, 2
• Chest X-ray (AP and lateral) 1, 2
• Liver ultrasound 1, 2
• Colonoscopy 1, 2

For sphincter-preservation surgery:

• Rectoscopy and/or endorectal ultrasonography should be performed 1, 2

CEA monitoring:

• Elevated CEA must be confirmed by repeat testing after minimum 1-month interval 1, 2

If preoperative colonoscopy was incomplete:

• Postoperative colonoscopy should be performed 6 months after treatment, then repeated within the first year and as indicated by results 1

Important note: CT and MRI are not indicated as routine follow-up examinations 1

Quality of Life Considerations

The combined modality approach (surgery plus chemoradiotherapy) provides significantly greater benefit despite increased toxicity, with improved disease-free survival and overall survival that justify the quality-of-life costs 7. Preoperative therapy results in improved postoperative bowel function compared to postoperative therapy 3. Sphincter preservation should be attempted whenever possible to maintain quality of life 1, 2.