Distinct clinical characteristics in stage III rectal cancer among different age groups and treatment outcomes after neoadjuvant chemoradiotherapy.

Abstract

There is a rapidly increasing incidence of early-onset colorectal cancer (EO-CRC) which threatens the survival of young people, while aging also represents a challenging clinical problem. We aimed to investigate the differences in the clinical characteristics and prognosis in stage III rectal cancer (RC), to help optimize treatment strategies. This study included 757 patients with stage III RC, all of whom received neoadjuvant chemoradiotherapy and total mesorectal excision. The whole cohort was categorized as very early onset (VEO, ⩽30 years old), early onset (EO, >30 years old, ⩽50 years old), intermediate onset (IO, >50 years, ⩽70 years), or late onset (LO, >70 years old). There were more female VEO patients than males, more mucinous adenocarcinoma, signet-ring cell carcinoma, pre-treatment cT4 stage, and higher pre-treatment serum carbohydrate antigen 19-9 compared with the other three groups. VEO patients had the worst survival with the highest RC-related mortality (34.5%), recurrence (13.8%), and metastasis (51.7%). LO patients had the highest non-RC-related mortality rate (16.6%). The Cox regression model showed VEO was a negative independent prognostic factor for disease-free survival [DFS, hazard ratio (HR): 2.830, 95% confidence interval (CI): 1.633-4.904, p < 0.001], distant metastasis-free survival (DMFS, HR: 2.969, 95% CI: 1.720-5.127, p < 0.001), overall survival (OS, HR: 2.164, 95% CI: 1.102-4.249, p = 0.025), and cancer-specific survival (CSS, HR: 2.321, 95% CI: 1.145-4.705, p = 0.020). LO was a negative independent factor on DFS (HR: 1.800, 95% CI: 1.113-2.911, p = 0.017), DMFS (HR: 1.903, 95% CI: 1.150-3.149, p = 0.012), OS (HR: 2.856, 95% CI: 1.745-4.583, p < 0.001), and CSS (HR: 2.248, 95% CI: 1.282-3.942, p = 0.005). VEO patients had better survival in the total neoadjuvant therapy-like (TNT-like) pattern on DFS (p = 0.039). IO patients receiving TNT-like patterns had better survival on DFS, OS, and CSS (p = 0.006, p = 0.018, p = 0.006, respectively). In stage III RC, VEO patients exhibited unique clinicopathological characteristics, with VEO a negative independent prognostic factor for DFS, DMFS, OS, and CSS. VEO and IO patients may benefit from a TNT-like treatment pattern.