3568 - Evaluation of Short-Term Efficacy and Long-Term Prognostic Factors following Neoadjuvant Chemoradiotherapy in Patients with Locally Advanced Rectal Cancer

Purpose/Objective(s):

To investigate the short-term efficacy, long-term prognosis and related factors of patients with locally advanced rectal cancer (LARC) after neoadjuvant chemoradiotherapy (nCRT) combined with surgery.

Materials/Methods:

The clinical data of 196 LARC patients who underwent nCRT and surgery in the Fourth Hospital of Hebei Medical University from 2014 to 2023 were retrospectively analyzed. The median follow-up time was 47.9 months (3.4-115.8 months). In this study, univariate analysis and logistic binary multivariate regression analysis were used to investigate the clinical factors affecting major pathological response (MPR). The Log-rank test was used to calculate p values, and the Kaplan-Meier method was used to calculate 5-year overall survival (OS) and 5-year disease-free survival (DFS). Univariate and multivariate Cox proportional hazards regression models were used to analyze the related factors affecting the DFS and OS of patients. The differences of MPR rate, DFS and OS between short-course radiotherapy (SCRT) plus consolidation chemotherapy and long-course chemoradiotherapy (LRCT), and between patients with or without total neoadjuvant therapy (TNT) were analyzed and compared.

Results:

Among the 196 patients with LARC who received treatment, 67 cases (34.18%) achieved MPR (TRG 0 + 1 grade). The nCRT approach (P=0.002), whether performing TNT (P=0.001), and age (P=0.019) were the relevant factors influencing MPR. The 3-year and 5-year OS and DFS of all patients in the group were 89.64%, 79.88% and 72.71%, 60.12%, respectively. The achievement of MPR was associated with good DFS (HR=0.59, 95% CI 0.33 - 0.93, P = 0.049), but not with OS (P > 0.05). The 5-year DFS and OS of patients in the MPR group and those who did not achieve MPR were 89.10% and 80.21%, 91.49% and 90.76%, respectively. The results of multivariate Cox analysis showed that lymphocyte count (HR=0.296, 95% CI 0.113-0.778, P=0.014) and recurrence and metastasis status (HR=13.522, 95% CI 4.488-40.739, P<0.001) were independent prognostic factors affecting OS of patients.

The patients were grouped according to whether they achieved MPR and 2-year DFS. The OS of the three groups, namely, those who achieved MPR+2yDFS, non-MPR+2yDFS, and non-2yDFS, showed significant statistical differences (P < 0.0001).

Conclusion:

(1) SCRT combined with consolidation chemotherapy and TNT could make LARC patients more likely to achieve MPR, but has no significant effect on DFS and OS.

(2) Patients with MPR had better DFS, but no significant improvement in OS. Patients with MPR and 2yDFS have better OS.

(3) Lymphocyte count, recurrence and metastasis are independent prognostic factors for OS.