Treatment Adequacy and Baseline Risk Modify the Association Between Adjuvant Chemotherapy and Survival After...

Area of Science:

• Oncology
• Gastrointestinal Surgery
• Clinical Research

Background:

• The role of adjuvant chemotherapy (ACT) in locally advanced rectal cancer (LARC) patients achieving pathological complete response (pCR) after neoadjuvant chemoradiotherapy (nCRT) is debated.
• It remains unclear if pCR signifies a consistently low-risk status for long-term outcomes.

Purpose of the Study:

• To evaluate the impact of ACT on survival outcomes in LARC patients who achieved pCR after nCRT and radical surgery.
• To determine if pCR is a uniformly low-risk state and identify factors influencing ACT benefit.

Main Methods:

• Retrospective analysis of 1069 LARC patients who achieved pCR following nCRT and surgery (2017-2022).
• Survival outcomes (overall survival [OS], disease-free survival [DFS]) were assessed based on ACT administration, treatment adequacy (≥4 cycles vs. <4 cycles), and baseline risk.
• Median follow-up was 49 months.

Main Results:

• No significant OS or DFS difference was found between patients who received ACT and those who did not.
• Patients completing adequate ACT (≥4 cycles) showed improved 4-year OS and DFS compared to those with fewer cycles or no ACT.
• This survival benefit was primarily observed in patients with baseline high-risk features; no differences were seen between ACT regimens.

Conclusions:

• Pathological complete response (pCR) in LARC does not indicate a uniformly low-risk state.
• Adequate adjuvant chemotherapy (ACT) may improve survival in selected high-risk LARC patients post-nCRT and surgery.
• A risk-adapted strategy for ACT warrants further investigation and prospective validation.