Purpose: This study aimed to improve the American Joint Committee on Cancer (AJCC) Tumor Node Metastases (TNM) staging system and demonstrate the improvement in prognostic accuracy and clinical management guidance in colon cancer using the novel prognostic score (P score).
Methods: Eligible patients were identified using the Surveillance, Epidemiology, and End Results database. A P score (based on age, tumor size, and tumor grade) was assigned to each patient. The Cox proportional hazards regression analyses were performed to identify independent factors associated with prognosis. The Kaplan-Meier survival curves were used to analyze the prognosis of patients with colon cancer with different P scores. The TNM staging system was compared with the P score in stages I-IV by calculating the concordance index.
Results: The multivariate Cox analysis indicated that a higher P score was independently associated with a higher risk of cancer-specific mortality. The Kaplan-Meier survival curves showed that the survival benefit gradually increased as the P score decreased. The concordance index rose from 0.5, 0.593, 0.633, and 0.551 of AJCC TNM staging system to 0.709, 0.651, 0.691, and 0.623 of P score in stages I-IV, respectively.
Conclusions: The P score was an independent prognostic factor of colon cancer and had a much better prognostic accuracy than the AJCC TNM staging system in all patients with colon cancer. It may help in identifying patients with high-risk stage II colon cancer who were candidates for adjuvant therapy and differentiating patients with stage III colon cancer for adjuvant therapy.
Keywords: Colon cancer; Prognostic score; SEER; Stage II; Stage III.