Immunotherapy-Induced Complete Response in dMMR Rectal Cancer-A Surgical Dilemma?

Area of Science:

• Oncology
• Gastroenterology
• Immunotherapy

Background:

• Deficient mismatch repair (dMMR) rectal cancer is rare (10%) but highly responsive to immune checkpoint inhibitors, often achieving complete remission.
• This high response rate presents a clinical challenge: standard surgery versus organ preservation with a watch-and-wait approach.

Purpose of the Study:

• To review current literature on response assessment, decision-making, oncological outcomes, and quality of life for dMMR rectal cancer patients achieving complete response.
• To compare surgical resection versus watch-and-wait management strategies.

Main Methods:

• Comprehensive literature review of clinical trials and retrospective studies up to 2025.
• Focus on response assessment, decision frameworks, oncological outcomes, and quality of life.

Main Results:

• Dostarlimab achieved 100% clinical complete response; surgery yielded 68-92% pathological complete response.
• Pseudoprogression and pseudoresidue complicate response assessment, requiring specialized evaluation.
• Both surgical and watch-and-wait approaches show 100% disease-free survival at 2-3 years.
• Watch-and-wait preserves organ integrity, avoiding colostomy (15.4%) and complications (19.3%).
• Surgery offers definitive tissue confirmation and reduces anxiety regarding recurrence.

Conclusions:

• The choice between surgery and watch-and-wait for dMMR rectal cancer involves balancing oncological outcomes with quality of life.
• Individualized decisions are crucial, considering patient preferences, functional preservation, and institutional capacity.