Abstract: Objective To explore whether young patients with peritoneal metastasis of colorectal cancer can achieve survival benefits through cytoreductive surgery (CRS) combined with hyperthermic intraperitoneal chemotherapy (HIPEC).Methods From June 2019 to June 2023,140 patients with peritoneal metastasis of colorectal cancer who received CRS combined with HIPEC were included.The perioperative outcomes and survival results were observed.The patients were divided into the young group (age ≤50 years old) and the non-young group (age >50 years old) according to their age.Survival curves were plotted using the Kaplan-Meier method,and survival differences between groups were compared using logrank.The endpoint of the study was 3-year tumor-specific survival rate (CSS).Results Among the 140 patients,there were 46 cases in the young group and 94 cases in the non-young group.Patients in the young group were more prone to peritoneal metastasis than those in the non-young group (78.3% vs.51.1%),and the proportion of patients with histological type of mucinous adenocarcinoma/signet ring cell carcinoma in the young group was significantly higher than that in the non-young group (29.8% vs.60.9%),and the difference was statistically significant (P<0.05).The 3-year CSS of the two groups of patients was similar (51.4% vs.35.9%).Multi-factor  Cox  regression analysis showed that mucous adenocarcinoma/signet ring cell carcinoma (HR:2.22,95%CI:1.06~4.75;P=0.043) and rectal origin (HR:2.54,95%CI:1.14~5.70;P=0.023) are independent risk factors for adverse CSS.Conclusion Young patients with peritoneal metastasis of colorectal cancer are more likely to have synchronous peritoneal metastasis.Although young patients show stronger tumor invasiveness and poor histological types,they can still achieve similar survival benefits to non-young patients through CRS combined with HIPEC.

Key words: colorectal cancer, peritoneal metastasis, cytoreductive surgery, hyperthermic intraperitoneal chemotherapy, prognosis, younger