What is correct regarding preoperative radiotherapy for rectal adenocarcinoma?

Preoperative Radiotherapy for Rectal Adenocarcinoma

Preoperative radiotherapy for rectal adenocarcinoma primarily reduces the risk of local recurrence rather than improving overall survival, with downstaging of tumors occurring in a significant proportion of cases. 1

Benefits of Preoperative Radiotherapy

• Local Recurrence Reduction: Preoperative radiotherapy significantly reduces local recurrence rates in patients with rectal cancer who undergo total mesorectal excision (TME) 1, 2

  • Reduction from 8.2% to 2.4% at two years in patients receiving preoperative radiotherapy plus surgery compared to surgery alone 2
  • Strong evidence (Level I, A) supporting its use in locally advanced cases 1

• Tumor Downstaging:

  • Long-course radiotherapy achieves tumor downstaging in 46-61% of cases 3
  • Higher rates of downstaging (up to 61%) are achieved when radiotherapy is combined with chemotherapy 3
  • Complete pathological response rates of approximately 13-15% with long-course radiotherapy 3, 4

• Survival Impact:

  • Overall survival benefit is marginal (approximately 2% absolute difference) 5
  • More significant survival benefit is observed when radiotherapy is combined with chemotherapy 3

• Sphincter Preservation:

  • Improves rates of sphincter-preserving surgery in low-lying tumors 4
  • Allows for low anterior resection instead of abdominoperineal resection in appropriate cases 4

Treatment Approach Based on Risk Stratification

Risk-Adapted Treatment Algorithm:

1. Very Early Tumors (cT1 sm1-2, N0):

   • Local excision (TEM) without radiotherapy 1

2. Early/Good Risk (cT1-2, early cT3a-b, N0):

   • Surgery alone with TME 1

3. Intermediate/Bad Risk (most cT3, some cT4a, N+):

   • Preoperative radiotherapy followed by TME 1
   • Options include:
     • Short-course: 25 Gy (5 Gy × 5 fractions) followed by surgery within 10 days 1
     • Long-course: 45-50.4 Gy (1.8-2 Gy/fraction) with 5-FU-based chemotherapy 1

4. Advanced/Ugly Risk (cT3 mrf+, cT4):

   • Preoperative chemoradiotherapy (50.4 Gy with 5-FU) followed by surgery 6-8 weeks later 1

Important Considerations and Caveats

• Timing of Surgery:

  • After short-course radiotherapy: surgery within 10 days 1
  • After long-course chemoradiotherapy: surgery after 6-8 weeks 1

• Postoperative Morbidity:

  • Modern studies show no significant increase in major postoperative complications with short-course preoperative radiotherapy 4
  • Earlier studies suggested increased but usually mild complications 6

• Patient Selection:

  • Preoperative radiotherapy is preferred over postoperative treatment due to better efficacy and lower toxicity 1
  • For elderly patients (≥80-85 years) or those unfit for chemoradiotherapy, short-course radiotherapy with delayed surgery may be an option 1

Conclusion

When evaluating the options presented in the question, the correct answer is D. Reduce risk of local recurrence and improve outcomes in rectal cancer. This is strongly supported by multiple guidelines and high-quality studies 1, 2. While preoperative radiotherapy does increase tumor downstaging, it occurs in more than 50% of cases (not "up to 50%" as stated in option C) 3. It has a marginal effect on overall survival (option A) 5, and modern techniques do not significantly increase postoperative morbidity (option B) 4.