Abstract:

Background and purpose: With the aging population, the number of elderly patients with colorectal cancer (CRC) is increasing. To date, elderly patients with stage Ⅱ CRC often receive a weakened chemotherapy regimen or even no chemotherapy after radical surgery, and It is still unclear whether this will lead to adverse oncological outcomes. This study aimed to explore the prognostic impact of advanced age on stage Ⅱ CRC patients after removing bias through a multivariate COX regression approach. Methods: We retrospectively collected data of 3314 colorectal cancer patients with postoperative pathology of stage Ⅱ, no history of previous tumors, no secondary primary tumors within 5 years after surgery and no preoperative neoadjuvant therapy. This study was reviewed by the medical ethics committee of Fudan University Shanghai Cancer Center (ethics number: 050432-4-2108*). The optimal threshold for calculating age relative to survival using survminer package of R software (version 3.0) (surv_cutpoint algorithm) was 73 years. We compared the clinical and pathological characteristics, overall survival (OS) and disease-free survival (DFS) between the older group (age>73 years) and the younger group (age≤73 years). The alignment diagram prediction model was drawn using the survival package and RMS package. Results: The elderly and non-elderly groups were evenly comparable in terms of gender, tumor location, differentiation, vascular invasion, perineural invasion and pT stage. Multivariate COX regression showed that advanced age was an independent prognostic risk factor for OS [hazard ratio (HR)=3.725 (3.051-4.549), P<0.001] and DFS [HR=2.431 (2.029-2.912), P<0.001]. The nomogram (alignment diagram) prediction model constructed based on multivariate COX regression could effectively evaluate the prognosis of stage Ⅱ CRC patients and provide guidance for practical clinical work. Conclusion: In stage Ⅱ CRC patients, older age is associated with shorter OS and DFS. Adequate intensity of adjuvant chemotherapy may be necessary. Treatment decisions can be adjusted based on the predicted model scores of the patient’s alignment diagram.

Key words: Colorectal cancer, Advanced age, Prognosis, Chemotherapy regimen, Prediction model